Mesiolingual root rotation for horizontal mandibular third molar extraction: position classification and surgical simulation

Unusual role in occlusion and mastication of a horizontal positioned erupted mandibular third molar: a rare case

Lower third molars are frequently extracted due to pathologies of the dental follicle, pericoronitis, advanced carious lesions, orthodontic reasons (risk of anterior tooth crowding) or causing periodontal or carious lesions in the distal area of the second molar. The case presented here is of a male patient that came to our Clinic experiencing pain in the distal area of one of his old bridges. The clinical examination revealed a malpositioned, but unusually functional third molar; it is a very rare situation for an initially impacted third molar to erupt in an almost horizontal position and not only to remain on the arch for a very long period of time, but also to contribute to mastication efficiency and occlusion, despite the fact that masticatory forces are distributed at a right angle on its long axis and that mastication takes place on the distal surface of the crown and root, and not on the usually occlusal cusped surface. The horizontal mandibular right third molar contributed to maintaining the vertical dimension of occlusion and the masticatory efficiency for a very long period of time; it also ensured a proper distribution of forces trough the long axis of the second premolar, since the distal contact of the third's molar crown with the second premolar helped it to resist masticatory forces and to remain on the arch, despite the prolonged absence of any mesial contact.

Buccal rotation for wholly impacted maxillary third molar extraction

BACKGROUND

Extracting wholly impacted maxillary 3rd molars faces difficulty due to the narrow surgical field, adjacent teeth resistances and risk of oroantral communication. This study is designed to introduce and evaluate the applicability of a novel method-buccal rotation to extract maxillary 3rd molars.

MATERIALS AND METHODS

In this cohort study, from October 1st 2020 to September 30th 2021, 72 wholly impacted maxillary 3rd molars were included. Based on the crowns with coronal 1/3, middle 1/3, apical 1/3 of the adjacent teeth roots, teeth were classified into position I, II, III. Based on the angles < 30°, ≥ 30°but < 60°, ≥ 60° to the adjacent teeth, teeth were classified into angulation A, B, C. Traditional method and novel method-buccal rotation were applied based on the surgical simulations. Surgical results were recorded. To analyze the data, Chi-square test was applied.

RESULTS

82.00% of teeth in position I and 50.00% in position II were designed to use traditional method, 83.33% in position III were using the novel method (p < 0.05). 81.25% of teeth in angulation A and 52.63% in angulation B were designed to use traditional method, 80.00% in angulation C were using the novel method (p < 0.05). Four cases got temporary complications.

CONCLUSION

Buccal rotation was applicable to extract the deep impacted maxillary third molars with large angles towards the adjacent teeth.

[Classification of lower impacted third molars position and their interrelationship with mandibular canal]

Classification of lower Impacted third molars position and their interrelationship with mandibular canal have a great scientific, theoretical and practical importance. An attempt to systematize and classify all anatomical impacted third molars position has been made by many authors. Based on our scientific literature search, we found: 8 impacted third molars classifications, 7 third molars and mandibular canal interposition classifications, as well as 5 classifications of mandibular canal anatomical branching variants. Most classifications are proposed by the author to predict third molar eruption perspective, determine level of operation complexity and prevent mandibular canal damage. New clinical classification development of impacted third molars interrelationship with mandibular canal, which combined the radiological PR, CBCT criteria, neurovascular bundle trauma prognosis, and operative technic choice can be actual.

3D-printed titanium surgical guides for extraction of horizontally impacted lower third molars

OBJECTIVES

This prospective study introduced a digitally designed sectioning guide and evaluated its feasibility for the extraction of horizontally impacted lower third molars.

MATERIALS AND METHODS

This study included 38 horizontally impacted lower third molars, randomly divided into experimental and control groups. The teeth were extracted using a 3D-printed titanium surgical guide in the experimental group; free-hand extractions were performed in the control group. The surgical duration, tooth sectioning duration, cortical bone perforation, and postoperative complications, including pain, swelling, trismus, dry socket, infection, and hemorrhage, were evaluated.

RESULTS

Although not statistically significant, guided surgery tended to reduce the number of tooth sectioning steps compared to free-hand extractions. There were no cases of cortical bone perforation in the experimental group. Although the surgical duration was greater in the experimental group (p < 0.05), there were no differences in postoperative pain, swelling, and trismus. There were no cases of postoperative infection and hemorrhage in either group.

CONCLUSIONS

3D-printed titanium surgical guides had superior accuracy and safety compared to free-hand surgery. Further studies with larger sample sizes are required to verify these findings.

CLINICAL RELEVANCE

The template improved the safety of tooth sectioning during impacted lower third molar surgery and resulted in a more predictable extraction. The narrow sectioning groove could fit comfortably with hypertrophic soft tissues in the posterior mandible.

Lingual bone thickness in the apical region of the horizontal mandibular third molar: A cross-sectional study in young Japanese

Background

Perforation of the lingual plate in the apical region of mandibular third molars will increase the risk of aberration and migration of the root tip and the risk of lingual nerve injury. The aim of this study was to analyze anatomical information, including relationships between the apical region of horizontally impacted mandibular third molars and lingual plates, in young Japanese.

Methods

Japanese patients, with horizontally impacted third molars, who underwent CT examination as a preoperative assessment for mandibular third molar extraction were included, and anatomical characteristics in the apical region of the right mandibular third molar were analyzed, in this study.

Results

A total of 121 patients were included based on the inclusion and exclusion criteria of this study. The mean and standard deviation of the bone thickness on the lingual side of the mandibular third molar in the apical region was 1.5 ± 1.6 mm, and the absence of lingual cortical bone in the apical region, namely, “perforation”, was observed in 44 patients. The statistical analysis revealed the predictors of cases with perforation as follows: gender, age, and the available space evaluated by Pell and Gregory classification.

Conclusions

This study clarified that “perforation” was sometimes observed in young Japanese, and that the predictors of those cases were as follows: gender, age, and the available space evaluated by Pell and Gregory classification.