CONGENITALLY MISSING MANDIBULAR SECOND

PREMOLARS

Supervisor: Prof. Maher Fouda

Prepared by: Nader A. Giacaman

Mansoura UniversityFaculty of Dentistry

Orthodontics Department

Definition :- Congenitally absence of a single tooth is called

agenesis or hypodontia.- When more than six teeth, excluding third molars, are

missing the term oligodontia is used. - The most extreme condition is complete absence of

permanent teeth and the term anodontia is used. - Oligodontia and anodontia are rare and are often seen in subjects with ectodermal dysplasia but hypodontia is

a relatively common finding.

Prevalence:

- Mandibular second premolars are the second most common missing teeth next to third

molars, and are absent in 2.5% to 5% of the population in the USA and Europe.

(Fines et al. 2003) (Josefsson et al. 1999)

- The most commonly missing teeth in this study were the mandibular second premolars,

followed by the mandibular and maxillary lateral incisors, and the maxillary second premolars. Symmetrical hypodontia was

predominant.(A survey of hypodontia in Japanese orthodontic patients. Endo T et al

2006).

Age at diagnosis: (Wisth et al. 1974, Steffensen 1981)

- The time of the diagnosis of agenesis is of importance.

- The treatment should rather be started early.

- The agenesis of the mandibular second premolar may be diagnosed as late as the

age of 9.

Treatment options Controlled slicing (8-11 yrs.): Early management

Extract or Keep (After age 11 yrs.)

1. Controlled slicing (8-11 yrs.): Early management

(Valencia et al. 2004) A simple method of allowing permanent first

molars to drift mesially by controlled slicing of deciduous second molar, thus facilitating

future orthodontic treatment. Controlled slicing between the ages of 8 and

9 years produced a bodily controlled mesial movement of the permanent first molar in less

than 1 year with no or minor rotations or inclination.

Controlled slicing technique:

(B) Slicing of distal crown portion of 1.5 2 second deciduous molar of to mm 699 700 - with a L or L high speed bur .

(A) Initial view .

(C) Mesial drift of first permanentmolar.

(D ) Parallelization of first permanent molar.

(E ) Hemisection and extraction of distal crown and root portion of

) deciduous second molar no pulpotomy or pulpectomy

(needed.

(F) Mesial drift.

(G ) Parallelization of first permanent molar.

(I,J) bodily migration of permanent molar .

(H) Extraction of mesial crown and root portion of deciduous

second molar.

Radiographic progress of controlled slicing onpatient with congenitally bilaterally missing second

premolars.

( C )4 months after initial distal slicing of crown portion (F )Final space

closure (12 months after initial slicing)

(D) After hemisection and

extraction of distal portion

(E )Bodily migration(note obliteration of

pulp chamber and continuity of Periodontal

ligament)

(A,B )Initial view

Occlusal follow up of mesial migration of Mandibular first permanent molars

(A) Several months after controlled slicing technique in mandibular arch.

Note initial bodily migration of permanent molars.

(B) 12 months after initial treatment.Note space closure and slight

rotation of mandibular permanent molars.

(C) After 24 months.Beginning orthodontic treatment

should be considered once space closure is almost complete.

(A)

(B)

(C)

3 months after the hemisection of deciduous second molar.

Note: 1. Maintenance of buccolingual

alveolar ridge. (Prevents the formation of a buccal bony

depression that can develop in extraction).

2. Bodily mesial migration of permanent first molar.

3. Lack of gingival inflammation.

Valencia et al. 2004, in their study of controlled slicing in the management of congenitally

missing lower 2nd premolars, concluded that:● Sequential slicing followed by hemisection and extraction of second deciduous molars in cases of congenitally missing second premolars showed a greater success rate compared with extraction.

● Permanent molars showed an 80% bodily space closure within 1 year, without mesial rotation and

midline loss, leading to better final orthodontic results (A,B).

● A 90% success rate was achieved when the technique was applied at an early age (8 to 9 years); the success rate

tended to decrease as age increased.

● Extraction of the deciduous second molars, without the controlled slicing technique, showed an average to poor

result in 75% of the cases.

2. Extract or Keep (After age 11 yrs.)(Peter Ngan et al. 2011)

Depends on Conditions lead us to Decisions

CONDITIONS: Age and distance of the primary tooth from the occlusal plane. Gender. Condition of the primary tooth and the orthodontic condition. Condition of the bone after extraction of the primary tooth.

DECISIONS: Decision to extract the primary second molar to replace the

missing premolar. Decision to extract the primary second molar to close the space

orthodontically. Decision to keep the primary second molar.

Age and distance of the primary tooth from the occlusal plane

vertical growth continues past the pubertal growth spurt and lasts longer than growth in the

sagittal and transverse dimensions

There is a correlation between the remaining growth and the final position of the primary molar

if it is ankylosed

Primary molars can often appear below the occlusal plane (infraocclusion) .

However, a step in the occlusal plane does not always mean the tooth is ankylosed

The best method to determine this is to compare the bone height to the adjacent molar or

premolar on a bitewing radiograph

1st Condition

Bone level of the primary molar = adjacent 1st permanent molar or premolar, then the deciduous tooth is erupting evenly (not ankylosed).

In a young patient, if there is an oblique step in the bone height from the primary to the permanent molar or premolar, then the tooth is probably

ankylosed. The tooth should therefore be extracted to prevent a potential alveolar ridge defect.

For example:

(A ) a mildly oblique step in the bone height and a minimal step in a 25 .yrs

, old patient may not be critical since there is little growth remaining in the

vertical dimension .

(B) a 12 .yrs o ld patient would indicate a much higher chance of severe

infraocclusion when growth is. complete The tooth should therefore

be extracted t o prevent a potential alveolar ridge defect .

Gender

Amount of growth of anterior facial height between the sexes:

Males > Females

At 2nd decade of life clinically insignificant.

(Fudalej et al. 2007)

2nd Condition

Condition of Mandibular 2nd deciduous molar:Large restoration / Severely decayed /

Severely resorbed rootOrthodontic condition

Crowding / Excessive proclination of the incisors / Presence of jaw discrepancies

Condition of the primary tooth and the orthodontic condition

(a-c) Pretreatment photographs (d) Panoramic radiograph (C) (Sufficient Crowding)

(a-c) Post-treatment of the same patient after orthodontic space closure (after extraction of the primary 2nd molars)

3rd Condition

Removal of the tooth

Condition of the bone after extraction of the primary tooth

4th Condition

Once the decision is made to extract the primary molar because of caries, resorbed roots, or ankylosis, the next step is

to decide how to manage the space!!!

The alveolar ridge narrowed by 25% in the first 4 years after extraction of the deciduous tooth; after 7 years it narrowed by

another 5% resulting in a total reduction in width of 30%.

(Ostler and Kokich 1994)

Kokich 2006 described a way to preserve the alveolar ridge after extraction. In one case he moved the first premolar into the

position of the missing second premolar. This tooth movement through the alveolar ridge allowed for adequate bone height and

thickness, and prevented the need for bone grafting prior to the placement of an implant to restore the first premolar space.

Decision to extract the primary second molar to replace the missing premolar

The best option for a congenitally missing mandibular 2nd premolar was to replace it with a single tooth implant (ADA Council on Scientific Affairs. 2004),

which has a 95% 10-year survival rate, but placement must be delayed until growth is

complete (Eckert and Wollan 1998). Replacement with a conventional fixed bridge has a 10-year survival

rate of about 84% (Napankangas et al.2002).

A girl, age 8 years 3 months, had bilateral infraocclusion mandibular 2nd deciduous molars (A).

The radiograph (B) showed that there is an oblique step in the bone height from the primary to the permanent 1st molar.

Patient 1

(kokich 2006)

All remaining deciduous teeth were extracted, no space maintaining appliances were placed, and the remaining

permanent teeth were allowed to erupt (C). Subsequent 1st premolars eruption brought the bone and

tissue up to their normal levels (D) and eliminated the alveolar defect.

Because the mandibular incisors were located so far to the lingual aspect (E), they were proclined labially, and space was opened between the premolar and the molar (F) for a

single-tooth implant (G). This implant was restored with a second premolar crown (H),

which helped to reestablish proper occlusion (I). The bone for the implant was created through orthodontic implant-site

development.

A, Woman was missing right mandibular second premolar and permanent first molar.

B and C, There was too much space for 1-tooth replacement and too little space for 2-tooth replacement.

(kokich 2006)

Patient 2

D and E, Implant was placed in 2nd premolar position and restored.

F, Bracket was placed on implant provisional (temporary) crown.

G, Implant was used to close remaining edentulous spaced.

H and I, Width of final premolar crown was normal, and Angle Class I molar and canine relationships were achieved.

A, Late-adolescent 14 yrs. 6 months girl was congenitally missing left mandibular second premolar, and deciduous molar

was ankylosed and submerged.

(kokich 2006)

Patient 3

B, Deciduous molar was extracted, resulting in significant narrowing of edentulous ridge.

C-E, First premolar was pushed distally into second premolar position.

F and G, Orthodontic movement allowed implant in newly regenerated bone.

H and I, After restoration of first premolar implant in second premolar position, it is difficult to see difference.

Decision to extract the primary second molar to close the space orthodontically

If it is decided to close the space, there are major orthodontic anchorage concerns. Closing the space of a primary molar, which is often 10 to 11 mm, is difficult at best and may result in a midline shift and flattening of the face (Northway 2004).

If the patient has a protrusive profile or moderate crowding, space closure is favored. However, in the absence of crowding and a good facial profile, space closure has

undesirable side-effects.

The introduction of temporary anchorage devices, such as miniscrew implants, has created more options for space

closure.

(a) Pretreatment photograph of a patient presenting with congenitally missing 2nd premolars and infra-occluded second deciduous molars.(b) Placement of a mini-implant between the mandibular canine and first premolar to protract posterior molars.(c) Post-treatment in the patient.

Decision to keep the primary second molar

A, A girl, age 12 years 4 months, was congenitally missing permanent right mandibular second premolar; deciduous second

molar was present and submerged below occlusal plane.

B, radiograph showed that root had not resorbed. Bone levels were flat between deciduous and adjacent permanent

teeth, tooth was maintained.

C-E, Tooth was too wide, so mesial and distal surfaces were reduced substantially.

F,G, Tooth was built up with composite to reduce caries risk.

H,I, Pulp was not damaged after space was closed and posterior teeth were brought into occlusion.

• The primary second molar is usually wider than the 2nd premolar. This makes it difficult to finish the case with

proper occlusal interdigitations. Typically the mandibular second primary molars are approximately 10 to 12 mm

wide. By reducing the mesiodistal width, the tooth can be narrowed to about 8.0 mm (Spear et al. 1997).

• It is usually necessary to add composite to the occlusal surface to obtain occlusal contact; the composite can be

added also interproximally to cover exposed dentin.

• If the primary molar is retained, the prognosis for its long term survival is more than 90% (Bjerklin et al. 2008).

Long-term follow-up of mandibular second primary molar in patients with agenesis of mandibular second

premolar.(Decision was made to keep the primary 2nd molar) (Al-Najjar 2006)

In this study, 40 patients were selected to the following criteria: agenesis of one or both mandibular second premolars in patients

20 years of age, or older.A general practitioner examined these patients at 1 to 2 years

interval with intra-oral radiographs at the regular check-ups. The registrations were divided into 13 stages were the last

registration at the age of 38-48 years. The mandibular second primary molars with no successors were examined clinically and radiographically at the distance between the adjacent permanent

teeth, infra occlusion and root resorptions.

The examination of the roots consisted of a subjective judgement of root resorption according to Bjerklin and Bennett (2000).

He concluded that, The distance between the first molar and the first

premolar adjacent to the persisting second primary molar was reduced mean less than 1 mm.

Infra occlusion was on average about 1 mm, even if the infra occlusion in single cases could be up to 9 mm.

Between the ages 20-30 years the root resorption of 90-95 % of the primary molars did not change.

-Intra-oral radiographs of a patient with agenesis of mandibular left second premolar.

-at 20 years of age (top) .-at 35 years of age (bottom).

-No changes in infra occlusion and root resorption-level between the two registrations .

(Al-Najjar 2006)

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