Analyzing the Fitting of Novel Preformed Osteosynthesis Plates for the Reduction and Fixation of Mandibular Fractures

Purpose: The known preformed osteosynthesis plates for the midface are helpful tools for a precise and fast fixation of repositioned fractures. The purpose of the current study is to analyze the precision of newly developed prototypes of preformed osteosynthesis plates for the mandible. Methods: Four newly designed preformed osteosynthesis plates, generated by a statistical shape model based on 115 CT scans, were virtually analyzed. The used plates were designed for symphyseal, parasymphyseal, angle, and condyle fractures. Each type of plate has three different sizes. For analysis, the shortest distance between the plate and the bone surface was measured, and the sum of the plate-to-bone distances over the whole surface was calculated. Results: A distance between plate and bone of less than 1.5 mm was defined as sufficient fitting. The plate for symphyseal fractures showed good fitting in 90% of the cases for size M, and in 84% for size L. For parasymphyseal fractures, size S fits in 80%, size M in 68%, and size L in 65% of the cases. Angle fractures with their specific plate show good fitting for size S in 53%, size M in 60%, and size L in 47%. The preformed plate for the condyle part fits for size S in 75%, for size M in 85%, and for size L in 74% of the cases. Conclusion: The newly developed mandible plates show sufficient clinical fitting to ensure adequate fracture reduction and fixation.

Should Degree of Third Molar Eruption Influence Operative Management of Mandibular Angle Fractures? A Systematic Review

Objective There is a growing trend toward evidence-based management of third molars in the fracture line of mandibular angle fractures (MAFs). This study aimed to differentiate MAF fixation complications by degree of third molar eruption and by extraction strategy in patients undergoing Champy fixation. Methods PubMed, EMBASE, OVID, SCOPUS, the Cochrane Library, and clinicaltrials.gov were queried through May 2020 for English-language publications for MAFs with third molar involvement for this systematic review. Bias was assessed using author-defined criteria. Relative risk (RR) of post-operative complications associated with extracted unerupted and retained partially erupted third molars (Group I) was calculated against controls of retained unerupted and extracted partially erupted third molars (Group II). Results Ten studies reported complications by eruption or extraction; however, only one study stratified complications by both eruption and extraction to meet inclusion criteria. The risk of bias was medium as only cases meeting defined follow-up were included. 73 cases (N) were included: 34 qualified for Group I and 39 for Group II. Quantitative synthesis of individual case data demonstrated significantly higher complication rate in Group I compared to Group II (23.5% vs 5.1%) (RR 4.6, 95% CI 1.04–20.1). No significant differences were observed between groups for infectious complications, mechanical complications, nonunion, or dehiscence. Reoperation was required significantly more often for Group I ( P = .043). Conclusions For MAFs involving the third molar, concomitant extraction of unerupted as well as retention of partially erupted third molars increases risk of complications with Champy fixation technique. For these patients, alternative strategies for fixation should be considered.

Evaluation of the exploration prospect and risk of marine gas shale, southern China: A case study of Wufeng-Longmaxi shales in the Jiaoshiba area and Niutitang shales in the Cen’gong area

The Wufeng-Longmaxi shales and the Niutitang shales are the most important organic-rich marine shales in southern China. To fully understand the significant difference in drilling results between the two sets of shales, the accumulation conditions of shale gas were systematically compared. The Niutitang shales have a superior material base of hydrocarbon generation for higher total organic carbon than the Wufeng-Longmaxi shales. Due to the influence of hydrothermal activities and carbonization of organic matter, however, the porosity, pore volume, pore size, and pore connectivity of Niutitang shales is obviously lower than that of Wufeng-Longmaxi shales. The natural fractures of Wufeng-Longmaxi shales are dominated by horizontal bedding fractures, and most of them are filled by calcite. By contrast, the high dip-angle fractures are more developed in the Niutitang shales. Especially, these fractures remain open in stages during the process of serious uplift and denudation movements. Thus, the seal conditions of the Niutitang shales are poor, which is further not conducive to the enrichment of shale gas. Our work also suggests that the exploration and development of highly over matured marine shales in southern China should follow the principle of “high to find low, and strong to find weak.”

A review of biomechanical studies for mandibular angle fracture internal fixation

Mandible fractures correspond to 19-40% of all facial fractures. Among all mandible fractures, 12-30% are fractures of the mandibular angle. These fractures are mainly caused by sports activities, interpersonal violence and car accidents. The presence of the third molar and the thin transverse bone area seem to be responsible for the frequent involvement of the mandibular angle in facial fractures. Before the advent of antibiotics, a high frequency of infection was always associated after an open reduction in mandibular angle fractures. Wired osteosynthesis and maxillomandibular fixation (MMF) were traditional methods for fixing mandibular angle fractures. The limitation of both methods has influenced the development of new approaches for the treatment of mandibular angle fractures. Currently, osteosynthesis of mandibular angle fractures with plates and screws has become an effective treatment option. Several forms are described in the literature as: fixation of bone segments with a miniplate on the upper edge of the mandible, fixation with two miniplates, lag screw or by a single rigid plate on the lower edge of the mandible. The purpose of this study was to summarize the main characteristics of biomechanical studies such as the type of mandible source used, the plating techniques employed, the plate material, and the loading protocols used to evaluate the stability of the fixation methods. The Medline (PubMed) database was searched combining relevant terms and pertinent articles in English were included. Articles had to meet the following inclusion criteria: be in vitro biomechanical studies evaluating fixation methods for mandibular angle fractures. A total of 27 articles fulfilled the inclusion criteria. Synthetic mandibles (n=12), animal mandibles (n=9), and human cadaveric mandibles (n=5) were used as the sample source to perform the biomechanical analysis. One article used both synthetic and human cadaveric mandibles. Also, a variety of fixation techniques was described such as mini-plates, lag-screws, reconstruction plates, and three-dimensional plates. The materials of the bone plates used were: stainless steel, commercially pure titanium, titanium alloy or bioresorbable. However, there was inconsistency in reporting the materials and not all studies clearly stated the material of the bone plates. For the biomechanical analysis, there was a high variation among all studies regarding the loading protocols used. The same side of fixation, the anterior part of the mandible (central incisors) or the contralateral side were reported as the dentate regions in which the force was applied. For more than 2 decades, in vitro biomechanical studies have been used to help researchers and clinicians in the field of Oral and Maxillofacial Surgery to properly evaluate and compare the different devices and techniques available for the treatment of mandibular angle fractures. Also, biomechanical studies are important to answer questions on fatigue performance and fracture strength on the gross level.

270 A Retrospective Analysis of The Impaction Status of Mandibular Third Molars as A Risk Factor for Fractures of Angle or Condylar Region of The Mandible

Background the position and angulation of mandibular third molars have both been found to influence the angle and condylar fractures. Objective: To identify whether there is an association between the depth and angulation of third molar impaction and the relative risk of fracture of the mandibular angle and condyle. Method Four-hundred and eighty-two panoramic dental radiographs were assessed for the period from January 2012 to June 2020. The study variables included the presence of mandibular third molars, position and angulation. The outcome variables were angle and condylar fractures. Results the mean age was 28.5 years (range 15-89) and 93.2% (n = 499) were male. Angle fractures were significantly more frequent with an impacted wisdom tooth (M3) ( p = 0.023) whereas condylar fractures were more commonly associated with a fully erupted M3. The highest incidence of angle fractures was observed with wisdom teeth classified as class II ( p = 0.026) and position B ( p = 0.05). In contrast, class I wisdom molars were more frequently associated with condylar fractures. With regards to the angulation of wisdom teeth, angles between 80 o – 100 o were highly correlated with angle fractures ( p = 0.020) whereas M3 angulations of 60 o – 80 o were related to condylar injuries (p = 0.025). Conclusions fractures of the mandibular angle were significantly associated with Class II and position B wisdom teeth whereas class I third molars were associated with fracture of the condyles. The likelihood of angle and condylar fractures almost doubled when M3 angulations were (80-100) and (60-80) respectively.

125 The Fate of The Third Molar in The Line of a Mandibular Angle Fracture: A Retrospective Study at A Tertiary Centre

Aim: To evaluate the risk of complications associated with retaining or extracting an asymptomatic third molar in the line of an angle fracture. Aiming to seek a consensus whether third molars should be extracted or retained during surgical repair of mandibular angle fractures. Method A retrospective study was undertaken at the Queen Elizabeth Hospital, Birmingham. 150 patients across a span of three years underwent open reduction and internal fixation of mandibular angle fractures with third molar involvement. Patients were classified into two groups, tooth retention during angle fracture and tooth removal during angle fracture repair. Hospital records were evaluated to seek the rate of post-operative complications at follow-up Results 162 angle fractures were identified with ipsilateral wisdom teeth present. In 37 cases the wisdom tooth was removed during surgery. 6 complications (16.2%) occurred in this group necessitating a return to theatre. In 125 cases the wisdom tooth was left in-situ. Complications necessitating a return to theatre occurred in 14 cases (11.1%). Conclusions This study indicates that retention of wisdom tooth overall did not significantly increase the risk of complications associated with angle fractures (p = 0.42). Where wisdom tooth pathology was noted its retention was associated with complications requiring a return to theatre (X2=4.40, p = 0.036).