perio prostho

Occlusal and Prosthetic Therapy

Occlusal andProsthetic TherapyTooth-Supported Fixed Partial Dentures

Rhea A. Ong, DMDClinical Periodontology and Implant Dentistry, 5th EditionJan Lindhe, Niklaus P. Lang, Thorkild KarringChapter 51, p1125-1137, 2008OUTLINE

Clinical symptoms of trauma from occlusionAngular bony defectsIncreased tooth mobilityProgressive (increasing) tooth mobilityTooth mobility crown excursion/root displacementInitial and secondary tooth mobilityClinical assessment of tooth mobility (physiologic and pathologic tooth mobility)Treatment of increased tooth mobilitySituation ISituation IISituation IIISituation IVSituation VTerminologyTrauma from occlusion is a term used to describe pathologic alterations or adaptive changes which develop in the periodontium as a result of undue force produced by the masticatory muscles.

Trauma from occlusion was defined by Stillman (1917) as a condition where injury results to the supporting structures of the teeth by the act of bringing the jaws into a closed position.

The World Health Organization (WHO) in 1978 defined trauma from occlusion as damage in the periodontium caused by stress on the teeth produced directly or indirectly by teeth of the opposing jaw.

In Glossary of Periodontic Terms (American Academy of Periodontology 1986), occlusal trauma was defined as an injury to the attachment apparatus as a result of excessive occlusal force.Clinical symptoms of traumafrom occlusionAngular bony defects-It has been claimed that angular bony defects and increased tooth mobility are important symptoms of trauma from occlusion (Glickman 1965, 1967).

-angular bony defects have been found at teeth affected by trauma from occlusion as well as at teeth with normal occlusal function (Waerhaug 1979)

This means that the presence of angular bony defects cannot per se be regarded as anexclusive symptom of trauma from occlusion.Increased tooth mobilityIncreased tooth mobility, determined clinically, is expressed in terms of amplitude of displacement of the crown of the tooth. Increased tooth mobility can, indeed, be observed in conjunction with trauma from occlusion. It may, however, also be the result of a reduction of the height of the alveolar bone with or without an accompanying angular bony defect caused by plaque-associated periodontal disease. Increased tooth mobility resulting from occlusal interferences may further indicate that the periodontal structures have become adapted to an altered functional demandProgressive (increasing) tooth mobilityProgressive tooth mobility can be identified only through a series of repeated tooth mobility measurements carried out over a period of several days or weeks.Tooth mobility crownexcursion/root displacement

The resistance of the tooth-supporting structures against displacement of the root is low in the initial phase of force application and the crown is moved only 5/10010/100 mm.This movement of the tooth was called initial tooth mobility (ITM) by Mhlemann (1954) and is the result of an intra-alveolar displacement of the root

- there are good reasons to assume that the initial displacement of the root (ITM) corresponds to a reorientation of the periodontal membrane fibers into a position of functional readiness towards tensile strengthWhen a larger force (225 kg (500 pounds)) is applied to the crown, the fiber bundles on the tension side cannot offer sufficient resistance to further root displacement. The additional displacement of the crown that is observed in secondary tooth mobilityPeriotestA new method for determining tooth mobility was presented by Schulte and co-workersPeriotest device measures the reaction of the periodontium to a defined percussion force which is applied to the tooth and delivered by a tapping instrument.Clinical assessment of tooth mobility(physiologic and pathologic tooth mobility)

it is not the length of the excursive movement of the crown that is important from a biologic point of view, but the displacement of the root with in its remaining periodontal ligament.

In plaque-associated periodontal disease, bone loss is a prominent feature, regarded as physiologic; the movement of the root within the space of its remaining normal periodontal ligament is normal.Only progressively increasing tooth mobility, which may occur in conjunction with trauma from occlusion, is characterized by active bone resorption and which indicates the presence of inflammatory alterations within the Periodontal ligament tissue, may be considered pathologic.Treatment of increasedtooth mobilitySituation IIncreased mobility of a tooth with increased width of the periodontal ligament but normal height of the alveolar boneIf a tooth (for instance a maxillary premolar) is fitted with an improper filling or crown restoration, occlusal interferences develop and the surrounding periodontal tissues become the seat of inflammatory reactions, i.e. trauma from occlusion (Fig. 51-5).

Since such traumatizing forces in teeth with normal periodontium or overt gingivitis cannot result in pocket formation or loss of connective tissue attachment, the resulting increased mobility of the tooth should be regarded as a physiologic adaptation of the periodontal tissues to the altered functional demands. A proper correction of the anatomy of the occlusal surface of such a tooth, i.e. occlusal adjustment, will normalize the relationship between the antagonizing teeth in occlusion, thereby eliminating the excessive forces. As a result, apposition of bone will occur in the zones previously exposed to resorption, the width of the periodontal ligament will become normalized and the tooth stabilized, it reassumes its normal mobility (Fig. 51-5).

In other words, resorption of alveolar bone which is caused by trauma from occlusion is a reversible process which can be treated by the elimination of occlusal interferences. The capacity for bone regeneration after resorption following trauma from occlusion has been documented in a number of animal experiments (Waerhaug & Randers-Hansen 1966; Polson et al. 1976a; Karring et al. 1982; Nyman et al. 1982).

In the presence of an untreated, plaque-associated lesion in the soft tissue, however, substantial bone regrowth did not always occur (Fig. 51-7) (Polson et al. 1976b).

Situation IIIncreased mobility of a tooth with increased width of the periodontal ligament and reduced height of the alveolar boneWhen a dentition has been properly treated for moderate to advanced periodontal disease, gingival health is established in areas of the dentition where teeth are surrounded by periodontal structures of reduced height.

If a tooth with a reduced periodontal tissue support is exposed to excessive horizontal forces (trauma from occlusion), inflammatory reactions develop in the pressure zones of the periodontal ligament with accompanying bone resorption. These alterations are similar to those which occur around a tooth with supporting structures of a normal height; the alveolar bone is resorbed, the width of the periodontal ligament is increased in the pressure/tension zones and the tooth becomes hypermobile (Fig. 51- 8a). If the excessive forces are reduced or eliminated by occlusal adjustment, bone apposition to the pretrauma level will occur, the periodontal ligament will regain its normal width and the tooth will become stabilized (Fig. 51-8b).Conclusion: situations I and IIOcclusal adjustment is an effective therapy against increased tooth mobility when such mobility is caused by an increased width of the periodontal ligament.Situation IIIIncreased mobility of a tooth with reduced height of the alveolar bone and normal width of the periodontal ligamentThe periodontal condition of this patient is illustrated by the probing depth, furcation involvement and tooth mobility data as well as the radiographs from the initial examination in Fig. 51-9 a.

Periodontal disease has progressed to a level where, around the maxillary teeth, only the apical third or less of the roots is invested in supporting alveolar bone.

The most likely definitive treatment should include: periodontal and adjunctive therapy in the following parts of the dentition: 15 and 25, and 13, 12, 11, 21, 22, 23. For functional and esthetic reasons, 14 and 24 obviously had to be replaced. The question now arose as to whether these two premolars should be replaced by two separate unilateral bridges, using 13, 15 and 23, 25 as abutment teeth, or if the increased mobility of these teeth and also of the anterior teeth (12, 11, 21, 22) (Fig. 51-9) called for a bridge of cross-arch design, with the extension 1525, to obtain a splinting effect.

Example: Case A, 64-year-old maleFrom the radiographs it can be seen that the increased mobility observed in the maxillary teeth of this patient is associated mainly with reduced height of the alveolar bone and not with increased width of the periodontal ligaments. This means that the mobility of the individual teeth should be regarded as normal or physiologic for teeth with such a reduced height of the supporting tissues. This in turn implies that the increased tooth mobility in the present case does not call for treatment unless it interferes with the chewing comfort or jeopardizes the position of the front teeth. This particular patient had not recognized any functional problems related to the increased mobility of his maxillary teeth. Consequently, there was no reason to install a cross-arch bridge in order to splint the teeth, i.e. to reduce tooth mobility.

Following proper treatment of the plaque associated periodontal lesions, two separate provisional bridges of unilateral design were produced (15, 14, 13; 23, 24, 25, 26 palatal root). The provisional acrylic bridges were used for 6 months during which the occlusion, the mobility of the two bridges and the position of the front teeth were all carefully monitored. When, after 6 months, no change of position of the lateral and central incisors had occurred and no increase of the mobility of the two provisional bridges had been noted, the definitive restorative therapy was performed.

Figure 51-10 presents radiographs obtained 10 years after initial therapy. The position of the front teeth and the mobility of the incisors and the two bridges have not changed during the course of the maintenance period. There has been no further loss of periodontal tissue support during the 10 years of observation, no further spread of the front teeth and no widening of the periodontal ligaments around the individual teeth, including the abutment teeth for the bridgework.Conclusion: situation IIIIncreased tooth mobility (or bridge mobility) as a result of reduced height of the alveolar bone can be accepted and splinting avoided, provided the occlusion is stable (no further migration or further increasing mobility of individual teeth), and provided the degree of existing mobility does not disturb the patients chewing ability or comfort.Situation IVProgressive (increasing) mobility of a tooth (teeth) as a result of gradually increasing width of the reduced periodontal ligament

Example: Case B, 26-year-old maleFigure 51-11 presents radiographs taken prior to therapy and Fig. 51-12 those obtained after periodontal treatment and preparation of the remaining teeth as abutments for two fi xed splints. All teeth except 13, 12, and 33 have lost around 75% or more of the alveolar bone and widened periodontal ligaments are a frequent fi nding. The four distal abutments for the two splints are root-separated molars, the maintained roots being the following: the palatal root of 17, the mesio-buccal root of 26, and the mesial roots of 36 and 47. It should be observed that tooth 24 is root-separated and the palatal root maintained with only minute amounts of periodontium left. Immediately prior to insertion of the two splints, all teeth except 13, 12, and 33 displayed a mobility varying between degrees 1 and 3.

From the radiographs in Fig. 51-12 it can be noted that there is an obvious risk of extraction of a number of teeth such as 24, 26, 47, 45, 44, 43, and 36 if the patient is allowed to bite with a normal chewing force without the splints in position. Despite the high degree of mobility of the individual teeth, the splints were entirely stable after insertion, and have maintained their stability during a maintenance period of more than 12 years.

Figure 51-13 describes the clinical status and Fig. 51-14 presents the radiographs obtained 10 years after therapy. From these radiographs it can be observed (compare with Fig. 51-12) that during the maintenance period there has been no further loss of alveolar bone or widening of the various periodontal ligament spaces.

Conclusion: situation IVSplinting is indicated when the periodontal support is so reduced that the mobility of the teeth is progressively increasing, i.e. when a tooth or a group of teeth arSituation VIncreased bridge mobility despite splinting

Example: Case C, 52-year-old femaleFigure 51-15 shows radiographs obtained at the initial examination. A 12-unit maxillary bridge was installed 1015 years prior to the present examination using 18, 15, 14, 13, 12, 11, 21, 22, 23, and 24 as abutments.

Radiographs obtained 5 years after therapy are shown in Fig. 51-16. The bridge/splint had a mobility of degree 1 immediately after its insertion and this mobility was unchanged 5 years later. The radiographs demonstrate that no further widening of the periodontal ligament occurred around the individual teeth during the maintenance period. When a cross-arch bridge/splint exhibits increased mobility, the center (fulcrum) of the movement must be identified. In order to prevent further increase in the mobility and/or to prevent displacement of the bridge, it is essential to design the occlusion in such a way that when the bridge/splint is in contact with the teeth of the opposing jaw, it is subjected to a balanced load, i.e. equal force on each side of the fulcrum. If this can be achieved, the force to which the bridge is exposed in occlusion can be used to retain the fixed prosthesis in proper balance (a further increase of mobility being thereby prevented).

The maxillary splint in the patient described in Figs. 51-15 and 51-16 exhibited increased mobility in a frontal direction. Considering the small amount of periodontal support left around the anterior teeth, it is obvious that there would have been a risk of frontal displacement of the total bridge had the bridge terminated at the last abutment tooth (23) on the left side of the jaw. The installation of cantilever units in the 24 and 25 region prevented such a displacement of the bridge/splint by the introduction of a force counteracting frontally directed forces during protrusive movements of the mandible (Fig. 51-17). In addition, the cantilever units provide bilateral contact relationship towards the mandibular teeth in the intercuspal position, i.e. bilateral stability of the bridge.In cases similar to the one described above, cantilever units can thus be used to prevent increasing mobility or displacement of a bridge/splint. It should, however, be pointed out that the insertion of cantilever units increases the risk of failures of a technical and biophysical character (fracture of the metal frame, fracture of abutment teeth, loss of retention, etc.).Conclusion: situation VAn increased mobility of a cross-arch bridge/splint can be accepted provided the mobility does not disturb chewing ability or comfort and the mobility of the splint is not progressively increasing.Long-term clinical outcomes of abutments treated with guided tissueregenerationPierpaolo Cortellini, MD, DMD,a Gabrielle Stalpers DMD,b Giovanpaolo Pini Prato, MD, DMD,cand Maurizio S. Tonetti, DMD, PhD, MMScdUniversity of Bern, Bern, Switzerland, and University of Florence, Florence, ItalyTHE JOURNAL OF PROSTHETIC DENTISTRY, Vol. 81 Num. 3, p305-311, 1999-MarchTerminologyAbutment1: that part of a structure that directly receives thrust or pressure; an anchorage 2: a tooth, a portion of a tooth, or that portion of a dental implant that serves to support and/or retain a prosthesis (Glossary of Prosthodontic Terms of the Academy of Prosthodontics, 2005)

Guided Tissue Regeneration any procedure that attempts to regenerate lost periodontal structures or alveolar process through differential tissue responses. Barrier techniques, using synthetic materials that may or may not resorb, to exclude epithelial ingrowth (periodontal regeneration) or connective tissue ingrowth (alveolar process regeneration) that is believed to interfere with regeneration (Glossary of Prosthodontic Terms of the Academy of Prosthodontics, 2005)

INTRABONY DEFECTIs define as a periodontal defect within the bone surrounded by one, two or three bony walls or a combination thereof (Glossary of Periodontal terms of the American Academy of Periodontology, 2001)INTRODUCTIONPeriodontal infections frequently result in a pattern of breakdown characterized by the presence of intrabony lesions. Angular bony defects have been treated with a variety of different surgical approaches, including resective and regenerative procedures. Among the others, guided tissue regeneration (GTR) is generally considered an efficacious and predictable approach for the treatment of deep intrabony defects around natural teeth. This defects are frequently located at strategically important abutments whose prognosis is key to the performance of the prosthodontic treatment plan.

A recent short-term study demonstrated that GTR can be successfully applied to treat intrabody defects around prosthetic abutments and a series of independent clinical trials have demonstrated that clinical attachment levels gained with GTR can be maintained over long periods around teeth that are nonabutments. A key issue, however, is the long-term stability of the clinical outcomes obtained with the treatment approach around prosthetic abutments.

The aim of this prospective study was to investigate the long-term stability of the clinical outcomes obtained with GTR in a cohort of patients presenting with strategically important abutments whose prognosis was compromised by deep intrabony defects.

Material and MethodsSubjects:Sixteen patients (5 men and 11 women)36 to 60 years of age (49.6 7.7 years) Patients with compromised abutments, selected after completion of initial therapy

Inclusion Criteria for Patients:(1) absence of systemic disease(2) no use of systemic medications(3) no known allergies(4) good oral hygiene (full mouth plaque score of 20% or lower)(5) absence of cigarette smokingpresence of advanced periodontal disease previously treated with scaling and root planing, and oral hygiene instructions* Each patient had at least 1 deep intrabony defect at an abutment of strategic importance for prosthetic rehabilitation. - Sixteen defects (1 defect per patient) Inclusion Criteria for Defects:(1) probing attachment loss equal to or greater than 6 mm(2) clinical and radiographic evidence of the presence of an intrabony defect at least 4 mm deep;(3) loss of 50% or more of the radiographic bone support at the defect site and (4) no furcation involvement

Clinical patient characterization:

Clinical measurements and standard periapical parallel technique radiographs were taken immediately before surgery, 1 year after the surgical procedure, and at the long-term follow-up visit, performed at least 4 years after GTR surgeryOral hygiene was measured with the full mouth plaque score (FMPS), recorded as the percentage of total surfaces (4 aspects per tooth)Bleeding on probing was assessed dichotomously at a force of 0.3 N. with a manual pressure sensitive probe (Brodontic probe equipped with a PCP-UNC 15 tip, Hu-Friedy)Full mouth bleeding scores (FMBS) were calculated. Probing pocket depths (PPD) taken and Clinical attachment levels (CAL) taken

*Both PPD and CAL were recorded to the nearest millimeter with a manual pressure sensitive probe (Brodontic probe equipped with a PCP-UNC 15 tip, Hu-Friedy) by a single investigator at the deepest interproximal point of the selected tooth.During the surgical procedure, the following defect morphologic parameters were evaluated after debridement of the area essentially as previously described:(1) distance from the cementoenamel junction (CEJ) to the bottom of the defect (CEJ-BD); (2) Distance from the CEJ to the most coronal extension of theinterproximal bone crest (CEJ-BC).

These measurements were performed at the deepest interproximal point of the defect.

The intrabony components of the defects (INFRA) were calculated as:INFRA = (CEJ-BD) (CEJ-BC)Surgical procedures and infection control:The treatment consisted of the placement of expanded-polytetrafluoroethylene (e-PTFE) barrier membranes (Gore-Tex Periodontal Material, Gore & Associates, Flagstaff, Ariz.) according to the principles of GTR.

After local anesthesia, the long-term provisional FPD was removed. Defect access was achieved through the elevation of full thickness buccal and lingual flaps. Intrasulcular incisions were performed at the defect site and extended buccally and lingually to the adjacent teeth. Crestal incisions were traced when edentulous ridges were adjacent to the defects. Particular attention was paid to fully preserve the soft tissues, especially at the defect sites. Vertical releasing incisions were performed when needed to improve access to the defects. Defects were fully debrided to expose the residual bony walls and roots were carefully planed with a combination of hand and mechanical instrumentation (Soniflex, Kavo, Dental GmBh, Biberach/Riss, Germany). Conditioning of the root surface was not performed.

Surgical procedures and infection control:

The optimal configuration of e-PTFE membranes was then selected according to defect morphologic parameters. Barriers were shaped, adapted, and positioned just coronal to the interproximal bone crest to cover the defects completely and to overlap 2 to 3 mm of the adjacent residual bone. Barrier membranes were firmly secured to the adjacent teeth with Teflon sutures (Gore-Tex Associates). Complete coverage of the membranes and primary closure of the flaps in the absence of tension was obtained with mattress sutures. Provisional FPDs were temporarily cemented, taking care that no cement extended subgingivally. No periodontal dressing was applied.


Tetracycline HCl 1 g/day were prescribed for the first postoperative week. Patients were instructed to avoid brushing and interdental cleaning of the treated site, and to refrain from chewing on the treated area while the membranes were in place. During this period, control of plaque accumulation was performed with 0.2% chlorhexidine mouthrinses 3 times daily, and with weekly recall visits for control and professional prophylaxis that consisted of accurate supragingival cleaning of the treated sites with hand instruments and a low-speed rubber cup with chlorhexidine gel.

Sutures were removed after 1 week.Surgical procedures and infection control:

6 weeks after placement, membraines were removed through elevating partial thickness buccal and lingual flaps. After membrane removal, the newly formed tissue was carefully protected with the gingival flaps.When dehiscence of the flaps did not allow proper protection of the regenerated tissue, free gingival grafts were positioned. The provisional FPD was immediately reinserted, and the periodontal dressing was positioned so as not to compress the experimental areas.

Sutures and dressing were removed after 1 week.


Patients were reinstructed: to rinse 3 times daily with 0.2% chlorhexidine, to avoid brushing and interdental cleaning, and to refrain from chewing on the experimental sites for a period of 6 weeks.

During this period, patients were recalled weekly for control visits and prophylaxis, as previously described. After this period, chlorhexidine was discontinued and full oral hygiene was resumed.


Patients were then maintained by monthly professional cleaning up to the 1 year reevaluation.

Provisional FPDs were removed every 3 to 4 months to control and clean the abutments and then immediately reinserted. Periodontal and/or prosthetic procedures involving the crevice of the treated abutments were avoided until the 1 year follow-up appointment, when the final FPDs were delivered.

After the 1 year reevaluation, all patients were included in a supportive periodontal care program with recall visits every 3 months.Radiographic evaluation of bone loss

Loss of radiographic bone was evaluated: at baseline, at the 1 year follow-up, and at reevaluation visits, 4 to 8 years afterward, with a modified version of a previously described method.

Linear measurements of bone loss, as described by Albandar et al, were taken on the radiographic images (original magnification 10). The position of the CEJ, as described by Schei et al, was identified. Whenever an interproximal restoration was present, its most apical extension was used instead of the CEJ. The most coronal region where the periodontal ligament maintained an even width was identified on the image in accordance with the criteria established by Bjrn et al.

Linear distances between: the CEJ and the root apex (root length), and the CEJ and the most apical extension of the intrabony defect (CEJ-BD), were recorded. The linear percentage of residual bone support (residual bone) was calculated as:1 (CEJ-BD/root length)

Radiographic evaluation of bone loss

Measurements were recorded by 2 investigators, who were blinded with respect to clinical measurements. The investigators had to reach agreement in terms of location of both anatomic and bone loss landmarks.Statistical analysis

Data were expressed as means standard deviations of 16 defects in 16 patients.

Significance of differences was tested by statistical application software (SAS Institute version 6.09, Cary, N.C.) at an a error level of .05.

Significant differences between:baseline and 1 yearbetween 1 year and long-term follow-up visitwere evaluated with the Wilcoxon ranked sum test.RESULTSBaseline patient and defect characteristics

Baseline FMPS and FMBS were 12.7% 2.9% and 10.7% 3.5%, respectively (Table I)

The experimental tooth population consisted of 3 incisors, 5 canines, 5 premolars, and 3 molars. Twelve teeth were located in the maxillae and 4 were located in the mandible.

Selected abutments exhibited deep periodontal lesions with a mean CAL loss of 10.8 2.2 mm, a PPD of 8.8 2.1 mm, and a radiographic residual bone support of 32% 17%. The average intrabony component depth was 6.9 1.5 mm (Table II).

Changes in oral hygiene parameters and patient compliance

At 1 year, FMPS decreased from 12.7% 2.9% to 8.6% 2.4. Similarly, FMBS decreased from 10.7% 3.5% to 7.1% 2.9%.At long-term follow-up visits performed 4 to 8 years after surgery, oral hygiene parameters were not significantly different from those detected at 1 year.

All patients regularly participated in the supportive periodontal care program.None of the patients reported smoking cigarettes during the investigation period.

Treatment effect at 1 year

The healing period progressed uneventfully, and no side effects or patient complaints were registered. Data presented in Table II show significant improvements after GTR therapy in all the treated sites in terms of CAL gains, PPD reduction, and gains in residual bone support at 1 year.

Treatment effect at 1 year

A 6.1 3 mm decrease in PPD was observed along with a CAL gain of 5.3 1.7 mm and an increase in the percentage of radiographic bone support of 31% 18% (Table III).

All differences between baseline and 1-year measurements were clinically and statistically highly significant. Only 12.5% of the cases resulted in CAL gains of 3 mm, 50% gained 4 to 5 mm, whereas 37.5% of the cases displayed CAL gains of 6 mm or more.

Long-term measurements

Long-term follow-up appointments were conducted after a period ranging from 4 to 8 years after GTR surgery (mean 5.6 1.6 years).


The comparison between the CAL measured at 1 year and at the long-term follow-up appointments did not reveal any clinically and statistically significant differences (0.1 0.6 mm, P=.4, NS) (Table III).


The percentages of radiographic residual bone measured at the long-term follow-up visits increased slightly compared with the percentages measured at 1 year (Table II), and the difference was statistically significant (P=.04) (Tables II and III).


A slight increase of 1 to 2 mm in PPDs was observed in some patients (Table II). The average difference between 1-year and long-term PPDs was statistically significant (0.8 0.8 mm, P=.004) (Table III).

DISCUSSIONThis investigation indicated that consistent clinical improvements can be obtained with GTR treatment of deep intrabony defects that affect prosthetic abutments. These improvements can be maintained over periods extending up to 8 years.

Thus, this study allows one to extend to abutments the conclusions of a series of independent clinical trials that demonstrated stability of the clinical outcomes obtained with GTR in nonabutments.

Substantial and highly predictable gains of tooth support in terms of CAL and bone were observed in our study at 1 year. CAL gains were 5.3 1.7 mm, on average, and 87.5% of cases gained 4 mm or more of CAL. These results are consistent with previous results obtained by the same group of clinicians. A similar pattern was observed in terms of bone changes, where average bone gain was 31% 18%. At baseline, radiographic bone loss extended to more than half of the root length in 87% of the cases, whereas this percentage decreased to only 37% 1 year after GTR. This observation is consistent with the previously reported association between CAL gains and bone gains after GTR in intrabony defects.Another relevant clinical result of the study was the significant decrease in PPD observed at 1 year. Residual PPD were 2.5 0.9 mm on average. Only 2 sites displayed pockets of 4 mm. The observed improvements in PPD probably played a role in facilitating the supportive periodontal care procedures of the involved abutments. PPD at the experimental sites increased slightly over time. At the long-term follow-up visit, the average PPD was 0.8 0.8 mm deeper than at 1 year. However, in most of the patients (7 sites), the changes in PPD were of 1 mm. Only in 4 cases they measured 2 mm.

After the 1-year follow-up visit, clinical outcomes were maintained over a period ranging 4 to 8 years in prosthetic abutments in patients who complied with a 3-month supportive periodontal care program, were not smokers, and maintained a high standard of oral hygiene.

CONCLUSIONSThe results of this study indicated that guided tissue regeneration (GTR) treatment with nonresorbable barrier membranes can predictably increase the periodontal support around abutments presenting with deep intrabony defects. The clinical outcomes obtained can be maintained over time in a nonsmoking population that complies with oral hygiene instructions and participates in a supervised supportive care program. Thus Guided tissue regeneration therapy can be one of the options discussed at the time of treatment plan for patients with complex perioprosthetic problems where strategic abutments are compromised by deep intrabony defects.

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