Retrospective study of the bone morphology in the posterior mandibular region. Evaluation of the prevalence and the degree of lingual concavity and their possible complications

BACKGROUND

In order to choose the appropriate implant size and to prevent complications, an oral surgeon must know the size and shape of the mandible. In the posterior mandibular region, a lingual undercut is often found and could represent a difficulty hard to manage if a lingual or buccal perforation occur. A large series of computed tomography (CT) images of the mandibular first molar was evaluated and the bone morphology, the prevalence and the degree of the lingual concavity in the first molar region were studied.

MATERIAL AND METHODS

One hundred and fifty-one computed tomography (CT) examinations of patients were retrospectively evaluated to determine anatomical variations in bone morphology in the submandibular fossa region.

RESULTS

A total of 151 subjects were included, consisting of 64 males (M) (42.4%) and 87 females (F) (57.6%). The under-cut type ridge was present in 64.2% of the cases. The concavity angle was 66.6 ± 8.9° (M) and 71.6 ± 8.4° (F) and the linear concavity depth 4.5 ± 2.3 mm (M) and 3.1 ± 1.7 mm (F) (p>0.05).

CONCLUSIONS

Mandibles with any lingual concavity present a potential increased risk of lingual cortical perforation during implant placement surgery. CT imaging allows characterizing the anatomy of the submandibular fossa and provides other important information for the preoperative assessment of the posterior mandible for dental implants placement.

Factors influencing the prophylactic removal of asymptomatic impacted lower third molars

The aim of this study was to analyse factors indicating prophylactic removal of impacted lower third molars, and how they, and possibly surgeon experience, influence the therapeutic decision-making process. A descriptive observational study was made of 40 asymptomatic impacted lower third molars. Orthopantomographs were scanned and presented to four professionals with different degrees of surgical experience. The examiners received information relating to patient age and sex, molar inclination and degree of impaction, and expressed their opinion on the necessity for teeth removal. There was a statistically significant relationship between examiner decision and the estimated probability of pathology if the molars were not removed (P<0.05). The degree of influence on the decision to extract was in decreasing order: estimated risk of complications, inclination of molar, age, degree of impaction and patient sex. No statistically significant differences (P>0.05) were observed between residents and trainers in terms of the decision to remove or estimated risk of complications. The management approach adopted by oral surgeons regarding the removal of asymptomatic impacted lower third molars depends upon the perceived risk of complications if such teeth are not removed, other factors being secondary. The surgical experience of the professional does not seem to influence treatment decision.