Isolated fracture of the coronoid process following a molar extraction: A rare case report.

Isolated coronoid process fractures are uncommon, and iatrogenic isolated fractures are extremely rare. This case describes a displaced fracture of an isolated coronoid process thought to be due to excessive force applied by a dentist that had been overlooked and left untreated for about a month. The patient was a woman in her late 50's and she had undergone a molar extraction. Her dentist had confused her symptoms of trismus, pain, and facial oedema with the complex tooth extraction procedure. Following a cone-beam computed tomography (CBCT) scan we showed that the mandibular coronoid process on her right side had suffered a longitudinal fracture, and the fractured fragment had rotated upwards and inwards. Following successful surgical elimination of the fragmented coronoid process, the patient received targeted physiotherapy sessions that yielded excellent results. At the five-month follow-up, the ability of the patient to open her mouth had improved enormously, and her facial appearance almost recovered to its original state.

Determination of critical-sized defect of mandible in a rabbit model: Micro-computed tomography, and histological evaluation.

Objective: To evaluate a rabbit model of mandibular box-shaped defects created through an intraoral approach and determine the minimum size defect that would not spontaneously heal during the rabbit's natural life (or critical-sized defect, CSD). Methods: Forty-five 6-month-old rabbits were randomly divided into five defect size groups (nine each). Mandibular box-shaped defects of different sizes (4, 5, 6, 8, and 10 mm) were created in each hemimandible, with the same width and depth (3 and 2 mm, respectively). Four, 8, and 12 weeks post-surgery, three animals per group were euthanized. New bone formation was assessed using micro-computed tomography (MCT) and histomorphometric analyses. Results: Box-shaped defects were successfully created in the buccal region between the incisor area and the anterior part of the mental foramen in rabbit mandibles. Twelve weeks post-surgery, MCT analysis showed that the defects in the 4, 5, and 6 mm groups were filled with new bone, while those in the 8 and 10 mm groups remained underfilled. Quantitative analysis revealed that the bone mass recovery percentage in the 8 and 10 mm groups was significantly lower than that in the other groups (p < 0.05). There was no significant difference in the bone mass recovery percentage between the 8 and 10 mm groups (p > 0.05). Histomorphometric analysis indicated that the area of new bone formation in the 8 and 10 mm groups was significantly lower than that in the remaining groups (p < 0.05). There was no significant difference in the new bone area between the 8 and 10 mm groups (p > 0.05). Conclusions: The dimensions of box-shaped CSD created in the rabbit mandible through an intraoral approach were 8 mm × 3 mm × 2 mm. This model may provide a clinically relevant base for future tissue engineering efforts in the mandible.