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Endodontic Endodontic SurgerySurgery

∗ Periradicular surgery, when indicated, should be considered an extension of nonsurgical treatment, because the underlying etiology of the disease process and the objectives of treatment are the same: prevention or elimination of apical periodontitis.

∗ Surgical root canal treatment should not be considered as somehow separate from nonsurgical treatment, although the instruments and techniques are obviously quite different.

INTRODUCTION

The following conditions present problems that must often

require surgical intervention

1-ANATOMY:

Calcific metamorphosis, canal aberrations, bifurcations, secondary roots, lateral canals, delta apexes and internal and external resorption

2-PROCEDURE:

Irretrievable separated instrument; perforations; ledges; zips; strips;

Inadequate and nonretrievable filling material; and irremovable posts, silver points, or gutta percha

SURGICAL CONSIDERATIONS (INDICATIONS(:

3- TRAUMA:

Class III and IV crown fracture, root fracture , subluxated or luxated teeth , and alveolar fractures and /or displacement often demand the removal of

both soft and hard tissue before they can be repaired or replaced

4- Biopsy:

Suspicious and /or nonhealing lesions, uncharacteristic signs and symptoms, and responses peculiar to treatment require

exploratory examination and laboratory evaluation.

5-Failing endodontics:

When regaining access to the canal or removing posts would risk a perforation or root fracture and/or create a restorative problem, a surgical approach may be more appropriate.

6-Expediency and convenience:

In lieu of multiple visits and an extended treatment plan for patients who travel long distances ,have major time limitations ,require special medical adjunctive therapy , or need treatment of multiple diseased teeth in the same arch, endodontic surgery may be combined with conventional

methods to accelerate the treatment process .

7-Emergency treatment:

Surgery is indicated when patients experiencing a superficial or deep cellulites and/or severe and uncontrollable pain require an incision and bone trephination to relieve the trapped pressure and/or fluids

8-culture:

In cases where conventional and adjunctive antibiotic therapy for odoriferous , painful , and repeatedly problematic teeth have been ineffective ,the periradicular area must be accessed to obtain a sample of

the exudates and lesions soft tissue (when present( .

Once obtained, this biopsy specimen can be forwarded to a qualified pathology laboratory for identification of the microorganisms, a histologic evaluation of the lesion, and a definitive diagnosis for an appropriate

treatment plan.

(1) The patient’s medical status (2) Anatomical considerations

)3( The practitioner’s skills and experience.

)4( Situations requiring professional judgment - Unnecessary teeth

- Nonrestorable teeth

-periodontal condition

-Uncooperative or unwilling patient

CONTRAINDICATIONS

1. Fistulative surgerya. Incision and drainage (I&D)b. Cortical trephinationc. Decompression procedures 2. Periradicular surgery (primary focus of this chapter)a. Curettageb. Root-end resectionc. Root-end preparationd. Root-end filling3. Corrective surgerya. Perforation repairi. Mechanical (iatrogenic)ii. Resorptiveb. Periodontal managementi. Root resectionii. Tooth resectionc. Intentional replantation

A CONTEMPORARY CLASSIFICATION OF ENDODONTIC

SURGERY

Objectives:

To determine the patient medical and dental condition

PREOPERATIVE EVALUATION OF THE PATIENT

Objectives:

To recognize, compensate for, or avoid prohibitive medical condition

)1(Major risk factorPatients presenting with the following medical problems should have treatment postponed until the condition has been compensated for, has improved, is under control or has been corrected and until the dentist has been given a written release by the patient's attending physicians

MEDICAL CONSIDERATION

1- Severe hypertensionThe danger of this condition lies in the possibility of sudden stroke, cardiovascular crisis, or

uncontrollable hemorrhage during treatment. 2-Myocardial infarct

There is a danger of stress -related relaps,coagulant antagonisms or hemorrhage during the procedure

3-cardiac insufficiencies The AHA (AMERICAN HEART ASSOCIATION) recommends endocarditis prophylaxis for patients with the following

conditions:-*High risk category :

-Prosthetic valves -bacterial endocarditis

-congenital heart disease*Moderate risk patients:

-Most congenital cardiac malformation-Rheumatic heart disease

-Mitral valve prolapse with valvar regurgitation

4-Bleeding disorders -Leukemia, Neutropenia and leukopenia

-May require hospitalization-Anticoagulants should be discontinued only by the

patient's attending physicians

5-Osteoradionecrosis:The loss of vascularity inhibits a normal inflammatory response which in turn impairs healing

6-Uncontrolled diabetes: Increase susceptibility to infection and delay healing

7-Prosthetic:Antibiotic prophylaxis isn't indicated for dental patients with pins, plates and

screws

-It is advisable to consider premedication in a small number of patients who may be at increased risk of hematogenous total infection as

-Inflammtory arthropathion (Rheumatoid arthritis,SLE (-Radiation

-Insulin dependant (TYPE I) diabetes-Induced immunosuppression

-Hemophilia-Malnourishment

)2(MINOR RISK CONDITIONCaution should be used when treating patient presenting with the

following medical condition: 1- Neurologic condition:

Patients are best served by preoperatively prescribing appropriate hypotonic, sedatives or analgesics

2-Respiratory condition:

-Asthmatic patient >>should be sedated Sever

-Emphysema >>> oxygen should be administered throughout the procedure

3-Cardiovascular condition: As mitral valve damage, prolapse, stenosis and pulmonary heart disease

-sedatives and prophylactic antibiotics should be administrated preoperatively

-blood pressure and pulse rate should be monitored4-Endocrine imbalance:

-consult the patient physician sedatives should be administered

5-Pregnancy: - consult the patient physician

-operation performed only during mild trimester-Avoid sedatives

-decrease anesthetic V.C6-Hemophilia:

-physician consultation -possible hospitalization

7- Immunologic disorders: - require consultation

-barrier control -prophylactic antibiotin

8-Infectious diseases:

- require consultation

-barrier control

-prophylactic antibiotic)All office personnel should be inoculated with hepatitis

B vaccine

*The patient must be thoroughly advised of the benefits, risks, and other treatment options and must be given an opportunity to ask questions.

*Premedication AS NSAID, Antibiotic, Chlorhexidine gluconate, sedations

PATIENT PREPARATION FOR SURGERY

-Administration of an NSAID, either before or up to 30 minutes after surgery, enhances postoperative analgesia.-Many types of NSAIDs are available, but ibuprofen remains the usual standard for comparison. Ibuprofen 400 mg provides analgesia approximately equal to that obtained with morphine 10 mg and significantly greater than that from codeine 60 mg, tramadol 100 mg, or acetaminophen 1000 mg

)1(NSAID

-The value of antibiotic prophylaxis before or after oral surgery is controversial, and the current best available evidence does not support the routine use of prophylactic antibiotics for periradicular surgery

)2(Antibiotic

Chlorhexidine gluconate (0.12%) often is recommended as a mouth rinse to reduce the number of surface microorganisms in the surgical field, and its use may be continued during the postoperative healing stage.

)3(Chlorhexidine gluconate

- Conscious sedation, either by an orally administered sedative or by nitrous oxide/oxygen inhalation analgesia, may be useful for patients who are anxious about the surgical procedure or dental treatment

-A typical protocol is a single dose at bedtime the evening before the procedure and a second dose 1 hour before the start of surgery

4(Sedative(

-The following instruments are necessary for performing an apicoectomy:∗Retractors.∗Microhead hand piece (straight and contra-angle) and microbur) ∗Special narrow periapical curette tips for preparation of the periapical cavity ∗Apical retrograde micro-mirror and micro-explorers∗Local anesthetic syringe and cartridges.∗Scalpel handle.

INSTRUMENTS AND OPERATORY SETUP

∗ Scalpel blade (no. 15).∗ Mirror.∗ Periosteal elevator.∗ Cotton pliers.∗ Small hemostat.∗ Suction tips (small, large).∗ Irrigation receptacle.∗ Periodontal curette.∗ Periapical curette.∗ Appropriate burs (round, fissure, inverted cone).

∗Miniaturized amalgam applicator for retrograde fillings ∗Narrow amalgam condensers ∗Scissors, needles and no. 3–0 and 4–0 sutures.∗Metal endodontic ruler.∗Gauze and cotton rolls/pellets.∗Syringe for irrigating surgical field.∗Saline solution.∗Needle holder.

Comparison of microsurgical scalpel (top) to #15C surgical blade. Microsurgical scalpels are particularly useful for the intrasulcular incision and for delicate dissection of the interproximal papillae.

Microcondensers in assorted shapes and sizes for root-end filling

The microcondenser should be selected to fit the root-end

Comparison of standard #5 mouth mirror (top) todiamond-coated micromirrors (CK Dental Specialties).

Micromirror used to inspect resected mesial root of amandibular first molar.

Retractors used in periradicular surgery.

Retractors positioned to expose the surgical site and protect adjacent soft tissues from injury. Care must be taken to rest the retractors only on bone, not on the reflected soft-tissue flap or on the neurovascular bundle as it exits the mental foramen.

Teflon sleeve and plugger specially designed for placementof MTA (DENTSPLY Tulsa Dental).

Messing gun–type syringe (CK Dental Specialties) can beused for placement of various root-end filling materials.

Another delivery system designed specifically for MTAplacement (Roydent). Kit includes a variety of tips for use in different areas of the mouth and a single-use Teflon plunger.

Hard plastic block with notches of varying shapes and sizes (G. Hartzell & Son). MTA is mixed on a glass slab to the consistency of wet sand and then packed into a notch. The applicator instrument is used to transfer the preformed plug of MTA from the block to the root end

Special narrow periapical curette tips that may be adapted to an ultrasonic device. They are used forpreparation of the periapical cavity in areas with limited access

Microhead handpiece compared to a conventional handpiece. With this handpiece, preparation of the periapical cavity is greatly facilitated in areas with limited access

Procedures:

)1(Local anesthesia for surgery)2(SURGICAL ACCESS

)3(PERIRADICULAR CURETTAGE AND BIOPSY)3(LOCALIZED HEMOSTASIS

)4(MANAGEMENT OF THE ROOT END)5(ROOT-END CAVITY PREPARATION

)6(ROOT CANAL END FILLING PROCEDURES)7(CLOSURE AND SUTURING

)8(POSTOPERATIVE CARE

)A)Periradicular surgery

-Direct subperiosteal infiltration not only is ineffective but also may be quite painful-Standard infiltration may not be totally effective -Regional block anesthesia techniques are preferred.*Mandibular blocks for posterior areas *bilateral mental blocks for the anterior mandible, *posterior superior alveolar blocks for the posterior maxilla, *infraorbital blocks for the premaxilla are preferred choices.- These may be supplemented by regional infiltration.

)1(Local anesthesia for surgery:

-If regional block anesthesia is not sufficient, one of the following methods may be used:*The first technique is infiltration starting peripheral to the swelling*A second technique is the use of topical ethylChloride

-If none of these procedures work, the incision for drainage may be done with intravenous sedation

Several general principles are important for designing the access to a diseased region:(1) The surgeon must have a thorough knowledge of the anatomic structures in relation to each other, including tooth anatomy.(2) The surgeon must be able to visualize the 3D nature of the structures in the soft and hard tissue (3) The trauma of the surgical procedure itself must be minimized(4) The tissue and instruments must be manipulated within a limited space, with the aim of removing diseased tissues and retaining healthy tissues.

)2(SURGICAL ACCESS:

IT INCLUDE:-INCISION AND REFLICTION -TISSUE RETRACTION

A vertical (rather than an angled) releasing incision severs fewer vessels, reducing the possibility of hemorrhage. Also, the blood supply to the tissue coronal to the incision is not compromised, which prevents localized ischemia and sloughing of these tissues

)A)Soft-Tissue Access

The following are general guidelines and principles:(1)Adequate blood supply to the reflected tissue is maintained with a wide flap base.(2) Incisions over bony defects or over the periradicular lesion should be avoided; these might cause postsurgical soft tissue fenestrations or nonunion of the incision.(3) The flap should be designed for maximum access by avoiding limited tissue reflection.(The actual bone resorption is larger than the size observed radiographically.)

Flap Design

(4) Acute angles in the flap are avoided. Sharp corners are difficult to reposition and suture and may become ischemic and slough, resulting in delayed healing and possibly scar formation.(5) Incisions and reflections include periosteum as part of the flap. Any remaining pieces or tags of cellular nonreflected periosteum will hemorrhage, compromising visibility.(6) The interdental papilla must not be split(incised through). The interdental papilla should be either fully included or excluded from the flap; dividing may result in sloughing of the tissue.

(7) Vertical incisions must be extended to allow the retractor to rest on bone and not crush portions of the flap.(8) A minimal flap, which should include at least one tooth on either side of the intended tooth, should be used. (9) Combinations of vertical and horizontal incisions are used to achieve various flap designs.

a. Full mucoperiosteal (intrasulcular incision including the dental papilla or papillary based) -Triangular: one vertical relieving incision-Rectangular: two vertical relieving incisions-Trapezoidal: two angled vertical relieving incisions-Horizontal: no vertical relieving incisionb. Limited mucoperiosteal -Curve submarginal (semilunar)-Freeform rectilinear submarginal (Ochsenbein-Luebke)

TYPES OF FLAP

.Most commonly used

. One vertical releasing incision; can extend to rectangular flap

. Keep 2 teeth away from Pathosis

1-TRIANGULAR (Intrasulcular(:

1. Excellent wound healing potential2.Minimal disruption of vascular supply3. Excellent visibility & access to defects4. Good flap reapproximation5. Easy to suture

ADVANTAGES

1.More difficult to incise & reflect 2.May be limited access due to single releasing incision3. Possible slight gingival recession

DISADVANTAGES

 . Extension of triangular flap. Two vertical releasing incisions. Horizontal intrasulcular incision. Use if increased reflection is needed

2-RECTANGULAR or TRAPEZOIDAL (intrasulcuar(:

1. Enhanced surgical access2. Excellent visibility3. Excellent wound healing potential4. Minimal disruption of vascular supply5. Good to view dehiscenses & fenestrations

ADVANTAGES

1. More difficult to incise & reflect2. Possible gingival recession3. More difficult wound closure than triangular flap

DISADVANTAGES

3-SUBMARGINAL SCALLOPED (Ochsenbein-

Luebke(:

1. Does not involve marginal or interdentalgingiva nor expose crestal bone2. Minimizes crestal bone loss & gingival recession (esthetics)3. Easy flap reapproximation

ADVANTAGES

1. Unable to extend flap if needed2. Disruption of bloodsupplty to marginal tissues; must rely on collateral 3. Limited mandibular use4. Possible flap shrinkage & scarring5. Limited visibility for root & crestal bone

DISADVANTAGES

. Full-thickness flap in alveolar mucosa at level of tooth apex

. Indication for long tooth only (max. canine)

. Seldom used due to poor access& scarring

. Hemostasis may be problem

4- SEMILUNAR FLAP:

1. Fast & easy to reflect; no exposure of crestal bone2. Unaltered soft tissue attachment level3. No involvement of marginal & interdental gingival

ADVANTAGES

1. Poor access (least), excessive scarring & flap shrinkage2. Blood supply interruption to adjacent tissues3. Limited use in mandible4. Unable to extend; may cross bony cavity

DISADVANTAGES

. Intrasulcular horizontal incision without vertical release

. Not used for apical surgery

. Used for root resects, root amps, hemisections, repair of cervical perfs. or resorptive defects

5-GINGIVAL (envelope(:

1. Good for perio-surgery2. Can convert to rectangular flap if needed

ADVANTAGES

1. Limited endo use2. Not for apical surgery3. No releasing incisions

*Note*The only flap designs indicated for palatal approach surgery are the horizontal (envelope) and the triangular, with the latter being preferred.

DISADVANTAGES

-A firm incision is made with a No. 15 or another suitable blade.-To prevent tearing during reflection, the incision must be made through periosteum to bone -The tissue is reflected with a sharp periosteal elevator beginning in the vertical incision and then raising the horizontal component.

Incision and tissue reflection

-Because periosteum is reflected as part of the flap, the elevator must firmly contact bone as the tissue is peeled back, using firm controlled force.

Elevator placed in the vertical incision for the first step in undermining flap reflection.

-The tissue is reflected to a level that will provide adequate access and visibility of the surgical site while allowing a retractor to be placed on sound bone

Reflection of the triangular flap to expose the root-end area

-The main goals of tissue retraction are to provide a clear view of the bony surgical site and to prevent further soft-tissue trauma.-The general principles of retraction are(1) Retractors should rest on solid cortical bone(2) Firm but light pressure should be used (3) Tearing, puncturing, and crushing of the soft tissue should be avoided

Tissue Retraction

)4( Sterile physiologic saline should be used periodically to maintain hydration of the reflected tissue

)5( The retractor should be large enough to protect the retracted soft tissue during surgical treatment

)6( If difficulty is encountered in stabilizing the retractor, a small groove can be cut into the Cortical plate to support it.

- Biologic principles govern the removal of bone for hard tissue access to diseased root ends:1-healthy hard tissue must be preserved

2-heat generation during the process must be minimized

)2(Hard-Tissue Access

1-The shape and composition of the bur(round fluted bur is better than fissure bur)2- The rotational speed(A high-speed handpiece that exhausts air from the base rather than the cutting end is recommended to reduce the risk of air embolism)3- The use of coolant (essential to improve healing)4- The pressure applied during cutting.(gentle brushstroke technique)

- Factors determine the amount of heat generated during bone removal:

*Note*-The root surface can be distinguished from the surrounding osseous tissue in four ways: (1) Root structure generally has a yellowish color, (2) Roots do not bleed when probed, (3) Root texture is smooth and hard as opposed to the granular and porous nature of bone, (4) It is surrounded by the periodontal ligament. (5) methylene blue dye

-when the bone exposing a lesion is dense misdirected penetration may lead to root damage

-bone length may be approximated from a prior radiograph or an intracanal file measurement or digitalized from a radiograph or guided by a radiograph of surgically placed lead-foil indicator

Objective

-curettage: To remove all pathologic tissue, foreign bodies, and root and bone particles from periradicular

area .

-Biopsy: To establish a definitive diagnosis by removing a tissue specimen from its bed then submitting it to an oral pathologist for a histologic evaluation

)3(PERIRADICULAR CURETTAGE AND BIOPSY

Technique

- Although the typical curette is shaped like a spoon and there is a tendency to use it as such, the sharp edge created when its concave surface faces bone makes it an extremely efficient cleaver.

- With the concave surface facing bone, the appropriate sized curette is wedged between the soft tissue of the lesion and the

border of the window entry .

- The sharp edge of the instrument is kept in constant contact with the bone as it penetrates the bone crypt .

- This cleaving motion easily strips the tissue from its bone attachment .

Curettage

Under normal conditions, little or no resistance will be met and the relatively soft tissue will easily disengage from the bone .

- Once the lesion is freed from the bone the curette can, with its convex surface facing bone, be used as a spoon to easily lift and remove the specimen from the crypt

- The walls of the bone cavity should appear smooth and free of all tissue tags.

- The specimen is immediately placed into a properly labeled biopsy bottle for histologic evaluation.

1-When there is resistance to lesion tissue removal ,it usually means the granulation tissue is firmly attached to the lingual aspect of the root surface. In this case ,it is better to gain un confined access to the condition by widening the osseous widow than to continue with a restricted ,laborious ,inefficient and time consuming segmental curette.

Problems

2-When further resistance is met in the depth of the crypt ,it generally indicates the lesion tissue has perforated the lingual plate of bone and has communicated with the palatal mucosa through the opening in the bone wall. ** This integration can be verified by placing a finger against the lingual mucosa that approximates the lesion location and physically feeling the curetting action within the depth of the crypt. To avoid perforating the mucosa ,the innermost

segment of the lesion requires delicate dissection .

3-When resistance continues and periodontal planning and scalpel dissection has been unsuccessful in freeing the lesion , a 2-to 3- mm segment of the apex should be resected ,and the tip and any adhering tissue

removed and included in the biopsy .

This technique is efficient and, because this root segment would normally be removed during the apicoectomy procedure ,its loss is of no consequence

4- Curetting large lesion often presents anesthesia problems . when a patient complains of pain during curetting of extensive lesion ,the procedure is stopped and the patient is

reanesthetized .

Objective:1-minimizes surgical time, surgical blood loss, and postoperative hemorrhage and swelling.2-enhances visibility and assessment of the root structure3-ensures the appropriate environment for placement of the current root-end filling materials and minimizes root-end filling contamination.

)3(LOCALIZED HEMOSTASIS

1-Collagen-Based Materials:As CollaCote , CollaStat , Hemocollagene, and Instat2-Surgicel 3-Gelfoam 4-Bone Wax 5-Ferric Sulfate

6-Calcium Sulfate 7-Calcium Sulfate 8-Epinephrine Pellets 9-Cautery/Electrosurgery

Local hemostatic agents

The basis for periradicular surgery is two fold: -The first objective is to remove the etiologic factor- The second is to prevent recontamination of the periradicular tissues once the etiologic agent has been removed. ( create an environment conducive to regeneration of the periodontium—that is, healing and regeneration of the alveolar bone, periodontal ligament, and cementum overlying the root end and root-end filling material.)

)4(MANAGEMENT OF THE ROOT END

-Root-end resection of approximately 3mm involves beveling of the apical portion of the root. This step is often an integral part of periradicular surgery and serves the following two purposes:1. It removes the untreated apical portion of the root and enables the operator to determine the cause of failure.2. It provides a flat surface to prepare a root end cavity and pack it with a root-end filling material.-When roots with more than one main canal are resected, isthmus tissue may be present, and the preparation should be modified to include the isthmus area

Root-End Resection (Apicoectomy(:

- Reduction of an apically fenestrated root apex below the level of the surrounding cortical bone allows remodeling of the bone over the tooth structure.-Apical sectioning is done with a tapered fissure bur in a high-speed handpiece and copious sterile saline irrigation The bevel should be made at approximately 45 degrees in a faciallingual direction, with the least amount of bevel to give maximum visibility to the root apex.-From a biologic perspective, the most appropriate angle of root-end resection is perpendicular to the long axis of the tooth .

-The conventional axiom for surface preparation of the resected root end has been to produce a smooth, flat root surface without sharp edges or spurs of root structure that might serve as irritants during the healing process. -smearing and shredding of the gutta-percha across the root face occurred only when the handpiece was moved across the root face in reverse direction in relation to the bur’s direction of rotation.

-Root surface conditioning removes the smear layer and provides a surface conducive to mechanical adhesion and cellular mechanisms for growth and attachment.

-Three solutions have been advocated for root surface modification: citric acid, tetracycline, and ethylenediamine tetraacetic acid (EDTA).

-All three solutions have enhanced fibroblast attachment to the root surface in vitro. However, citric acid is the only solution tested in an endodontic surgical application.

-The ideal preparation is a class I cavity prepared along the long axis of the tooth to a depth of at least 3 mm

-Traditionally, a microhandpiece with a rotating bur has been used, but with the advent of ultrasonic tips designed specifically for this purpose root-end preparations now are most often performed with the ultrasonic technique.

)5(ROOT-END CAVITY PREPARATION

Diagram of a perpendicular root-end preparation and 3-mm-deep cavity preparation along the long axis of the root

A root-end filling material should have the following characteristics:1. Well sealing2. Well tolerated by the periradicular tissue3. Nonresorbable4. Easily inserted5. Unaffected by moisture6. Radiographic visibility7. Ability to allow regeneration of periradicular tissues

ROOT-END FILLING MATERIALS

*Many materials have been used as root-end fillings, including: -gutta-percha, - polycarboxylate cements, -silver cones, amalgam, -Cavit (3M ESPE St. Paul, MN), -zinc phosphate cement, -gold foil -titanium screws. -Zinc oxide eugenol cements (IRM and SuperEBA),-Glass ionomer cement -Diaket-Composite resins (Retroplast), -Resin–glass ionomer hybrids (Geristore),-Mineral trioxide aggregate (ProRoot-MTA).

Types of root-end filling material

)1(Gutta-percha

Advantages

-semisolid,

-nonresorbable,

-biocompaltible material-good handling properties

Disadvantages

-mositure sensitive -The apical seal depends on the structure of gutta-percha , its degree of condensation, and the nature and the amount of sealer used-there is atendency for its margins to open when the canal root interface is cut , heated or burnished

It has been the most widely used material

Disadvantages

Its shrinkage lead to leakage It produce corrosive byproductMercury and tin contaminationMoisture sensitiveA retentive designed cavity preparation is required Tissue tattooing(not used anteriorly)Scattered particles are not resorbable

)2(Amalgam

)3(zinc oxide (super EPA, IRM and CAVIT(

Advantages

-have recently gained popularity because they don’t stain soft or hard tissue and are nongalvanic when placed in contact with posts

Disadvantages

-moisture sensitive-initial tissue irritation-leakage

)4(Dentine bonding agents

Advantages

-they adapt better-leak less than amalgam

Disadvantages

-ineffective bond against moist dentine-all composites are known to leak after insertion

)5(Glass ionomers

Advantages

-chemically bond to the dentine

Disadvantages

-root preparation must be dry-the seal is adversely affected by moisture and low PH

)6(Mineral trioxide aggregate(MTA(

Advantages

-The powder consists of fine hydrophilic particles that set in the presence of moisture or blood

Disadvantages

-Inability to flush the crypt clean without washing out the filling-2-4 hrs setting time  

)1(Surgical site should be isolated and aspirated of all fluids and blood

)6(ROOT CANAL END FILLING PROCEDURES

)2(The cavity preparation is flushed clean and thoroughly dried with air blown through a 30-gauge short needle attached to a Stropko irrigator/drier

)3(Test dryness and blood by short cut paper point

(4)For amalgam filling, 2 thin layer of cavity varnish should be painted in the cavity(5)For the gutta-percha, the cavity wall should be dressed with sealer

)6( Microcondensers are used to vertically condense the amalagam to minimize voids and maximize compaction

)7(All other filling materials including pastes, must be mixed according to manufacturer's standards and carried to the preparation by minicarriers or missing guns carvers

)8( Plugers of various angels and sizes are used to condense the material

)9(All excess and flash should be curetted and aspirated from the site with Lucas curette

)10(The borders should be examined under high magnification to evaluate the interface seal

)11(The surface then should be burnished with a finishing bur

(12)The cavity is carefully inspected for flaws or loss of marginal integrity by retromirrors (13)Any gauze, pellets and or bone wax should be removed and the surgical site should be cleaned

(14)A radiograph is finally taken to evaluate the filling

(1)The osteotomy site is gently curetted and irrigated with sterile saline or water to remove any remnants of hemostatic agents and packing materials.(2)Some bleeding is encouraged at this point, because theblood clot forms the initial scaffold for subsequent healing and repair.(3)If indicated, grafting materials or barriers may be placed at this time.

)7(CLOSURE AND SUTURING

(4)Slight undermining of the unreflected soft tissue adjacent to the flap facilitates the placement of sutures. (5)The flap is then repositioned (6)When suturing is complete, chilled, sterile, moist cotton gauze is again placed over the flap, and pressure is applied for 5 minutes.(7)The patient is given a cold compress and instructed to hold it on the face in the surgical area—on for 20 minutes then off for 20 minutes—for the rest of the day.(8)The patient also is given verbal and written postoperative instructions

∗ )Pressure to the area provides stability for the initial fibrin stage of clot formation and reduced the possibility of excessive postoperative bleeding and hematoma formation under the flap(

Gauze sponge moistened with saline and applied to flap both before and after suturing.

-Sutures are classified as absorbable or nonabsorbable,∗-size is designated by two Arabic numbers, one a zero, being separated by a hyphen (3-0, 4-0, 5-0, etc).∗(The higher the first number, the smaller the diameter of the suture material).∗-Suture material in size 5-0 is most commonly used, although some clinicians preferslightly larger (4-0) or smaller (6-0) suture. ∗(Sutures smaller than 6-0 tend to cut through the relatively fragile oral tissues when tied with the tension required to approximate wound margins).

Selection of the Suture Material

)1( Silk suture material)2( Resorbable suture materials (plain gut and

chromic gut(

)3( Suture materials with a smooth Teflon or polybutilate coating (e.g., Tevdec and Ethibond, respectively(

)4( Synthetic monofilament suture materials (e.g., Supramid and Monocryl)(5) Gortex (expanded PTEE-Teflon) sutures

Types of suturing material

-Has been commonly used in dental surgery for decades and is both inexpensive and easy to handle

but it tends to support bacterial growth and allows for a wicking effect around the sutures , for these reasons, other materials are preferable to silk

Silk suture material

-Are not routinely used for periradicular surgery-May be indicated if the patient will be unavailable for the regular

suture-removal appointment (48 to 96 hours after surgery) or if the suture will be used in areas of the mouth where access is very

difficult.

-The primary problem with resorbable suture materials is the variable rate of resorption; that is, sutures may weaken and dissolve too soon or, more commonly, remain in the incision area for longer than desired.

Resorbable suture materials (plain gut and chromic gut(

-Are particularly well suited for use in periradicular surgery.

Suture materials with a smooth Teflon or polybutilate coating (e.g., Tevdec and Ethibond,

respectively)

-Are also commonly used

-These materials are easy to handle and do not promote bacterial growth or wicking of oral fluids to the same extent as silk.

Synthetic monofilament suture materials (e.g., Supramid and Monocryl(

Have many desirable properties but are more expensive than the previously mentioned materials.

Gortex (expanded PTEE-Teflon) sutures

*The final selection of an appropriate surgical needle is based on a combination of factors including

-The location of the incision, -The size and shape of the interdental embrasure, - The flap design, and the suture technique planned.

NEEDLE SELECTION

* A needle with a reverse cutting edge (the cutting edge is on the outside of the curve) is preferable

Conventional cutting needles are not recommended because the cutting edge on the inside curvature tends to pull through the flap edge; reverse cutting suture needles prevent suture material from tearing through surgical flaps.

As previously noted, NSAIDs generally are the preferred class of drugs for managing postoperative pain Ibuprofen (400 to 800 mg) or an equivalentNSAID typically is given before or immediately after surgery and can be continued for several days postoperatively as needed. When additional pain relief is required, a narcotic such as codeine, hydrocodone, or tramadol may be added to the standard NSAID regimen. (This strategy may result in a synergistic effect, and therefore greater pain relief, than would be expected with the separate analgesic value of each drug).

)8(POSTOPERATIVE CARE

1. Limit physical activity for the first 24 hours. Easy activity is OK but be careful and do not bump your face where the surgery was done. You should not drink any alcohol or use any tobacco (smoke or chew) for the next 3 days.2. It is important that you have a good diet and drink plenty of liquids for the first few days after surgery. Juices, soups, and other soft foods, like yogurt and puddings, are suggested. Liquid meals, like Sego, Slender, and Carnation Instant Breakfast, can be used. You can buy these at most food stores. Avoid carbonated beverages.

INSTRUCTIONS FOR POSTOPERATIVE CARE

FOLLOWING ENDODONTIC SURGERY

3. Do not brush in the area of the incision for first 3 days, then use a soft brush very carefully; use warm salt water rinses (dilute 1/8 teaspoon salt per 8 oz glass of water) and rinse for 1 minute swishing the surgical area every 2 hours during the day. Continue rinses until 2 days after sutures removed.4. Do not lift up your lip or pull back your cheek to look where the surgery was done. This may loosen the stitches, causing them to tear the gum tissue and start bleeding.

5. A little bleeding from where the surgery was done is normal. This should only last for a few hours. You may also have a little swelling and bruising of your face. This should only last for a few days.6. Place an ice bag (cold) on your face where the surgery was done. You should leave it on for 20 minutes and take it off for 20 minutes. You should do this for 6 to 8 hours. After 8 hours, the ice bag (cold) should not be used. The next day after surgery, you can put a soft, wet, hot towel on your face where the surgery was done. Do this as often as you can for the next 2 to 3 days.

7.You should use the pain medicine you were given or recommended to you, as needed.

8. Rinse your mouth with one tablespoon of the chlorhexidine mouthwash

(Peridex) you were given or prescribed. This should be done two times a day (once in the morning and once at night before going to bed). You should do this for 5 days.

9. The stitches that were placed need to be taken out in a few days (removed 2 to 4 days after surgery). You will be told when to return. It is important that you come in to have this done!!10. You will be coming back to the office several times during the next few months so we can evaluate how you are healing. These are very important visits and you should come in even if everything feels OK.11. If you have any problems or if you have any questions, you should call the office. The office phone number is xxx-xxxx. If you call after regular office hours or on the weekend, you will be given instructions on how to page the doctor on call.

-Local anesthesia is rarely required, although application of a topical anesthetic may be helpful, especially to releasing incisions in nonkeratinized mucosa. -Sharp suture scissors or a #12 scalpel blade can be used to cut the sutures before they are removed with cotton pliers or tissue forceps.

)9(POST SURGICAL EVALUATION AND SUTURE REMOVAL

-A transient bacteremia can be expected after suture removal, even when a preprocedural chlorhexidine mouth rinse is used.-Antibiotic coverage should be considered only for patients at high risk of developing bacterial endocarditis.

-If healing is progressing normally at the suture removal appointment, the patient does not need to be seen again in the office until the first scheduled recall examination, typically 3 to 12 months after surgery. -Phone contact with the patient approximately 7 to 10 days after suture removal is recommended to confirm the absence of problems. -Patients with questionable healing at the suture-removal appointment should be reevaluated in the office in 7 to 10 days or sooner if necessary.

Surgery involves the manipulation of both: A-soft tissues (periosteum, gingiva, periodontal ligament, and alveolar mucosa) and B-hard tissues (dentin, cementum, and bone)

HEALING

*Healing involves:

-clotting,

-inflammation,

-epithelialization,

-connective tissue healing,

-and maturation and remodeling of both connective tissue and bone

*)Clotting and inflammation consist of both chemical and cellular phases. (

)A)SOFT TISSUE HEALING

1-The clotting mechanism is important because it is based on the conversion of fibrinogen to fibrin; under pressure, the clot should be a thin layer.

Failure of a clot to form results in leakage of blood into the wound site.

2-The inflammatory components of healing are a complex

network of both extrinsic and intrinsic elements

3- Initial epithelial healing consists of the formation of the epithelial barrier, made up of layers of epithelial cells

that depend on the underlying connective tissue for nutrients.

This epithelial layer migrates along the fibrin surface until it makes contact with epithelial cells from the opposite border of the wound, forming an epithelial bridge.

4-The connective tissue component comes from fibroblasts, which are differentiated from ectomesenchymal cells and are attracted to the wound site by cellular and humoral mediators.Adjacent blood vessels provide nutrients for the fibroblasts and their precursors, which elaborate collagen, initially type III, followed by type 1. Macrophages are an important part of these processes.

5-As healing matures, there is a decrease in the amount of inflammation and numbers of fibroblasts, accompanied by deaggregation and reaggregation of collagen with formation of collagen fibers into a more organized

As with soft tissue, the hard tissue response is based on the fibroblast, which results in synthesis of ground substance, cementum, and bone matrix formation . New cementum deposition from cementoblasts begins about 12 days after surgery; eventually a thin layer of cementum may cover resected dentin and even certain root end filling materials

)B)HARD TISSUE HEALING

Complete periapical healing and formation of cellular cementum (arrows) adjacent to mineral trioxide aggregate when it is used as a root-end filling material in monkeys

Osseous healing begins by the proliferation ofendosteal cells into the coagulum of the wound site. At 12 to 14 days, woven trabeculae and osteocytes appear, leading to early maturation of the collagen matrix at about 30 days. This process occurs from inside to outside, ending in the formation of mature lamellar bone ,32-35 which is visible radiographically

A, Failed root canal treatment requiring surgery. B, The root end is resected, and a cavity is prepared and is filled with MTA. C, One-year recall shows complete healing

(1)PainPostoperative pain typically peaks the day of surgery, and swelling reaches its maximum 1 to 2 days after surgery.As previously noted, good evidence supports the use of prophylactic NSAID therapy and a long-acting local anesthetic to reduce the magnitude and duration of postoperative pain.

MANAGEMENT OF SURGICALCOMPLICATIONS

(2)bleedingPatients should be advised that some postoperative oozing of blood is normal, but significant bleeding is uncommon and may require attention. Most bleeding can be controlled by applying steady pressure for 20 to 30 minutes, typically with a piece of moist cotton gauze or a tea bag.

-Bleeding that persists requires attention by the clinician. -Pressure to the area and injection of a local anesthetic containing 1:50,000 epinephrine are reasonable first steps.

-If bleeding continues, it may be necessary to remove the sutures and search for a small severed blood vessel. (When located, the blood vessel can be crushed or cauterized to control bleeding. Cauterization may be performed with a heat source commonly used for warm

obturation techniques(.

Local hemostatic agents, as previously described, may also be used. Occasionally, a patient may require hospitalization and surgical intervention to control bleeding, but this is an extremely rare event.

(3)EcchymosisThis condition is self-limiting and does not affect the prognosis.Moist heat applied to the area may be helpful, although complete resolution of the discoloration may take up to 2 weeks. Heat should not be applied to the face during the first 24 hours after surgery

(4) Sinus exposure-Not uncommon. -Postoperative antibiotics and decongestants are often recommended but this practice is controversial-no evidence supports the routine use of antibiotics and decongestants in these cases

(5) paresthesiaThe incidence of damage to the inferior alveolar nerve after third molar surgery is approximately1.3%, with only about 25% of these cases resulting in permanent injury. Unless the nerve is resected during surgery, most patients can be expected to return to normal sensation within 3 to 4 months. If the paresthesia does not show signs of resolving within 10 to 12 weeks, referral and evaluation for possible neuromicrosurgical repair should be considered

(6) postsurgical infectionsPostsurgical infections are rare. For this reason, peritreatment systemic antibiotic therapy is seldom required and is not considered part of routine postsurgical care in healthy patients. The most common causes of postsurgical infections following periradicular surgery are the result of inadequate aseptic techniques (These are under the direct control of the endodontic surgeon).

The clinical signs and symptoms of a postsurgical infection are usually evident 36 to 48 hours after surgery. The most common indications are progressively increasing pain and swelling. Suppuration, elevated temperature, and lymphadenopathy may or may not be present. Systemic antibiotic therapy should be initiated immediately when indicated. Chlorhexidine oral rinses should continue for 4 to 6 days following surgery (2 to 3 days following suture removal).

(7) Staining of mucosa due to amalgam that remained at the surgical field (amalgam tattoo)

(8) Healing disturbancesif the semilunar incision is made over the bony deficit or if the flap, after reapproximation, is not positioned on healthy bone.

(9) Splattering of amalgam at the operation siteDue to inadequate apical isolation and improper manipulations for removal of excess filling material

CASE (1(

Extensive periapical lesion at maxillary right lateral incisor. Indication for apicoectomy

Clinical photograph of case shown in Arrow points to possible location of lesion

Surgical procedure for removal of periapical lesion, together with apicoectomy at lateral incisor of maxilla. Incision for creation of trapezoidal flap. a Diagrammatic illustration. b Clinical photograph

Reflection of mucoperiosteum and exposure of labial alveolar plate after elevation of flap. a Diagrammaticillustration. b Clinical photograph

Removal of labial bone covering apical third of root. a Diagrammatic illustration. b Clinical photograph

Removal of periapical lesion with hemostat and curette. a Diagrammatic illustration. b Clinical photograph

Resection of apex with fissure bur and beveling at a 45° angle. The resection faces the surgeon and is at adistance of 2–3 mm from the root tip

Diagrammatic illustration (a) and clinical photograph (b) showing beveled root of lateral incisor

Preparation of cavity at root tip of tooth usingmicrohead handpiece. a Diagrammatic illustration. b Clinical photograph

Cavity created (inverted cone-shaped) where filling material is to be placed. a Diagrammatic illustration.b Clinical photograph

Placement of filling material in cavity of apex using miniaturized amalgam applicator. a Diagrammaticillustration. b Clinical photograph

Condensing of amalgam with narrow amalgam condenser. a Diagrammatic illustration. b Clinical photograph

Diagrammatic illustration (a) and clinical photograph (b) showing the apex of the tooth with retrogradefilling complete

Operation site and placement of sutures. a Diagrammatic illustration. b Clinical photograph

Radiograph taken before suturing of flap,whichshows retrograde amalgam filling

CASES(2)

CASE (2(

Radiograph of maxillary central incisor, showingperiapical lesion and unsatisfactory filling of the root canal

Surgical procedure for apicoectomy at maxillary left central incisor. Semilunar incision made for flap.a Diagrammatic illustration. b Clinical photograph

Reflection of flap and retraction with broad end of periosteal elevator. a Diagrammatic illustration.b Clinical photograph

Removal of bone covering apex of tooth. a Diagrammatic illustration. b Clinical photograph

Exposing periapical lesion and apex of tooth together after removal of respective buccal bone. a Diagrammaticillustration. b Clinical photograph

Removal of periapical lesion with hemostat and periapical curette. a Diagrammatic illustration. b ClinicalPhotograph

Resection of apex of tooth at a 45° angle. a Diagrammatic illustration. b Clinical photograph

Preparation of cavity at apex with microhead handpiece. a Diagrammatic illustration. b Clinical photograph

Diagrammatic illustration (a) and clinical photograph (b) showing prepared cavity ready for placement ofFilling

Placement of filling at root tip with miniaturized amalgam applicator. a Diagrammatic illustration. b ClinicalPhotograph

Condensing amalgam at periapical cavity with narrow amalgam condenser. a Diagrammatic illustration.b Clinical photograph

Operation site after placement of sutures. a Diagrammatic illustration. b Clinical photograph

Periapical radiograph taken after suturing of flap, showing retrograde amalgam filling

 Objective:-To evacuate exudate and purulence, which are potent and toxic irritants. -Removal speeds healing and reduces discomfort resulting from the irritants and from the buildup of pressure. *Note*Performance of most intraoral incisions is generally within the ability of general practitioners.

)B)INCISION AND DRAINAGE

(1)Swelling originating from an acute apical abscess of pulpal origin(2)Occasionally drainage is performed through the soft tissue even if it has also been obtained through the tooth. The reason is that there may be two (or more) separate, noncommunicating abscesses-one at the apex and another in a submucosal location or in ananatomic space

)3(Incising a fluctuant swelling releases purulence immediately and provides rapid relief.

Indication

(1)Diffuse swellings are not usually (2)Incised Patients with prolonged bleeding or clotting times must be treated cautiously, and hematologic screening is oftenindicated. (3)An abscess in an anatomic space may require more involved treatment; the patient should be referred to an oral and maxillofacial surgeon for an extraoral or aggressive intraoral incision

Contraindication:

(1) Anesthesia (as discussed)(2)Incision-The incision is made horizontally or vertically with a No. 11, 12, or 15 blade. -Vertical incisions are parallel with the major blood vessels and nerves and leave very little scarring.-The incision should be made firmly through periosteum to bone. -If the swelling is fluctuant, pus usuallyflows immediately, followed by blood. Occasionally, there is only a serosanguineous exudate, which is acceptable. -If the swelling is nonfluctuant, the predominant flow is hemorrhagic.

PROCEDURE

(3)Drainage -A small closed hemostat may be placed in the incision and then opened to enlarge the draining tract. -The initial incision and subsequent enlargement usually provide the needed drainage.-If a drain is necessary because of limited initial drainage, a self-retentive I -shaped or "Christmas tree" drain cut from a rubber dam or a piece of iodoform gauze is placed (suturing is optional) in the incision -The drain should be removed after 2 to 3 days; if it is not sutured, the patient may remove the drain at home.

Definition: These procedures are especially designed to correct pathologic or iatrogenic entities (procedure errors) that have damaged the root and are not correctable via the pulp space (internally).

)C)CORRECTIVE SURGERY

(1)Procedural ErrorsCorrection of root perforations often presents a more difficult challenge than procedures that merely involve periradicular surgery. Typically these accidents occur during access, canal preparation, or restorative procedures (usually post placement). (2) Resorptive PerforationsResorptive root perforations typically occur as sequel to trauma or internal bleaching procedures.

INDICATIONS

(1)Furcation perforation:-the greatest potential for furcation perforations are the maxillary and mandibular molars.-When a perforation occurs in this area of the tooth, the initial attempt at repair should be from an internal, nonsurgical approach.-When surgery is necessary, a buccalmucoperiosteal flap is reflected, the furcation bony defect is curetted to remove any pathologic tissue, and the perforation site is repaired.

)1(Perforation repair:

(2)Strip perforation: (in the cervical one-third of the Root)-occur most frequently in the thin distal aspects of the mesial roots of mandibular molars and the mesiobuccal roots of maxillary molars.-Nonsurgical repair should be the first treatment option in these cases. -If surgical repair is deemed necessary, the perforation must be accessed and visualized through a window created in the buccal bone.-If neither the nonsurgical nor surgical options are feasible, other possible treatment options include root amputation, hemisection, intentional replantation, or extraction followed by the placement of a bridge or osseointegrated implant.

Root amputation: -is the removal of one or more roots of a multirooted tooth. The involved root(s) is (are) separated at the junction of and into the crown-performed in maxillary molars, but it can be performed in mandibular molars.

)2( Root amputation, Hemisection and Bicuspidization

Hemisection is the surgical division of a multirooted tooth.

- In mandibular molars the tooth is divided buccolingually through the bifurcation

-In maxillary molars the cut is made mesiodistally, also through the furcation.The defective or periodontally involved root and its coronal crown are then removed.

Bicuspidization -is a surgical division (as in hemisection, usually a mandibular molar), but the crown and root of both halves are retained. -If severe bone loss or destruction of tooth structure is confined primarily to the furcation area, hemisection and furcal curettage may allow retention of both halves(Each half may be restored to approximate a bicuspid, hence the term bicuspidization).

Root Amputationor Hemisection

Indications-The presence of severe bone loss in a nonsurgical treatable periodontally involved- Untreatable roots because of broken instruments, perforations, caries, resorption, vertical fractures, or calcified canals-Strategically important root(s)

Contraindications

-Insufficient bony support for the remaining root(s)-Root fusion or proximity such that root separation is not possible-Strong abutment teeth available (the involved tooth should be extracted and a prosthesis fabricated)-Inability to complete root canal treatment on the remaining root(s)

Root amputation- is performed by making an angled cut from the furcation to the proximal aspect to separate the root from the crown. -The crown remains intact, and the root is removed. Therefore, the crown is cantilevered over the extracted root segment and remains in contact with the approximating tooth. A second approach is to use an angled vertical cut in which the crown above the root to be amputated is recontoured, decreasing the occlusal forces and making the procedure easier.-As the crown is shaped, the bur is gradually angled into the root, resulting in good anatomic contour.

TECHNIQUES

Hemisection- involves making a vertical cut through the crown into the furcation. -This results in complete separation of the hemisected section (crown and root) from the tooth segment that is retained.- The defective half of the tooth is extracted.

Bicuspidization

Indications

-Furcation perforation-Furcation pathosis from periodontal disease-Buccolingual cervical caries or fracture into furcation

Contraindications

-Deep furcation (thick floor of pulp chamber)-Unrestorable half-Periodontal disease (each half must be –periodontally sound)-Inability to complete root canal treatment on either half-Root fusion

- is performed after a vertical cut is made through the crown into the furcation with a fissure bur. This procedure results in complete separation of the roots and creation of two separate crowns. After healing of tissues the teeth can be restored to form two separate premolars.

TECHNIQUE

*Note*-These techniques may or may not require flap reflection. Often, if the root is periodontally involved, it is removed without a flap. -If bony recontouring is indicated, a flap is necessary before root resection is carried out. -A sulcular flap design is often possible without a vertical releasing incision.

)3(INTENTIONAL REPLANTATION

INDICATIONS-when surgical access is very limited or presents unacceptable risks. (Mandibular second molars are a common example for this technique because of the typically thick overlying buccal bone, shallow vestibular depth, and proximity of the root apices to the mandibularCanal)

CONTRAINDICATIONS

-Teeth with flared or moderately curved roots

-the presence of periodontal disease.

-The tooth should be extracted with minimal trauma to the tooth and socket. (Ideally, elevators are not used, and the root surface is not engaged with forceps). -All instruments and materials for root-end preparation and filling should be arranged before extraction to minimize extraoral working time.

-The root surface must be kept moist by wrapping the root with gauze soaked in a physiologic solution such as

Hank’s Balanced Salt Solution.

PROCEDURE

-After root-end preparation and filling (described previously), the tooth is replanted, and the buccal bone is compressed.-The patient may be instructed to bite on a cotton roll or other semisolid object to help position the tooth properly in the socket.- Occlusal adjustment is indicated to minimize traumatic forces on the tooth during the initial stage of healing.-A splint may be applied, but this is often not necessary. -The patient should eat a soft diet and avoid sticky foods, candy, and chewing gum for at least 7 to 10 days.

∗A, The mandibular second molar remained symptomatic after an unsuccessful attempt was made to negotiate the apical portion of both mesial canals and to retrieve the separated instrument from one of the canals. Due to the close proximity of the mandibular canal to the apices of the roots of the second molar, an intentional replantation procedure was recommended rather than periapical surgery; B, Forcep extraction; C, Root ends resected; D, Tooth reimplanted; E, Acrylic splint placed; F, Immediate postoperative radiograph; G, Soft tissues are healthy and tooth is asymptomatic at the 6-month follow-up; H, There has been a reduction in the size of the periapical radiolucent defect on the 6-month follow-up radiograph.

*Varying results have been reported for root removal.

*Success depends on the following factors:-Case selection-Cutting and preparing the tooth without creating additional damage-Restoration-Good oral hygiene-Development of caries (most common cause of failure)-Root fractures-Excessive occlusal forces-Poor restorative procedures-Untreatable endodontic problems

∗-Periodontal disease (second most common cause of failure(

PROGNOSIS

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