Cephalometric studies of the mandible, its masticatory muscles and vasculature of growing Göttingen Minipigs — A comparative anatomical study to refine experimental mandibular surgery

Over many decades, the Göttingen Minipig has been used as a large animal model in experimental surgical research of the mandible. Recently several authors have raised concerns over the use of the Göttingen Minipig in this research area, observing problems with post-operative wound healing and loosening implants. To reduce these complications during and after surgery and to improve animal welfare in mandibular surgery research, the present study elucidated how comparable the mandible of minipigs is to that of humans and whether these complications could be caused by specific anatomical characteristics of the minipigs’ mandible, its masticatory muscles and associated vasculature. Twenty-two mandibular cephalometric parameters were measured on CT scans of Göttingen Minipigs aged between 12 and 21 months. Ultimately, we compared this data with human data reported in the scientific literature. In addition, image segmentation was used to determine the masticatory muscle morphology and the configuration of the mandibular blood vessels. Compared to data of humans, significant differences in the mandibular anatomy of minipigs were found. Of the 22 parameters measured only four were found to be highly comparable, whilst the others were not. The 3D examinations of the minipigs vasculature showed a very prominent deep facial vein directly medial to the mandibular ramus and potentially interfering with the sectional plane of mandibular distraction osteogenesis. Damage to this vessel could result in inaccessible bleeding. The findings of this study suggest that Göttingen Minipigs are not ideal animal models for experimental mandibular surgery research. Nevertheless if these minipigs are used the authors recommend that radiographic techniques, such as computed tomography, be used in the specific planning procedures for the mandibular surgical experiments. In addition, it is advisable to choose suitable age groups and customize implants based on the mandibular dimensions reported in this study

Ectopic premolar tooth in the sigmoid notch

Impaction of a mandibular premolar is relatively uncommon. Ectopic placement is more unusual and there has been no discussion in the literature of an ectopic mandibular premolar in the coronoid process. In this case report, we present an impacted ectopic mandibular permanent premolar in the sigmoid notch (incisura mandibulae) region. Etiology of the tooth and treatment options are discussed and illustrated by Cone Beam Computed Tomography (CBCT) images

Coronectomy of deeply impacted lower third molar : incidence of outcomes and complications after one year follow-up

Objectives: The purpose of present study was to assess the surgical management of impacted third molar with proximity to the inferior alveolar nerve and complications associated with coronectomy in a series of patients undergoing third molar surgery. Material and Methods: The position of the mandibular canal in relation to the mandibular third molar region and mandibular foramen in the front part of the mandible (i.e., third molar in close proximity to the inferior alveolar nerve [IAN] or not) was identified on panoramic radiographs of patients scheduled for third molar extraction. Results: Close proximity to the IAN was observed in 64 patients (35 females, 29 males) with an impacted mandibular third molar. Coronectomy was performed in these patients. The most common complication was tooth migration away from the mandibular canal (n = 14), followed by root exposure (n = 5). Re-operation to remove the root was performed in cases with periapical infection and root exposure. Conclusions: The results indicate that coronectomy can be considered a reasonable and safe treatment alternative for patients who demonstrate elevated risk for injury to the inferior alveolar nerve with removal of the third molars. Coronectomy did not increase the incidence of damage to the inferior alveolar nerve and would be safer than complete extraction in situations in which the root of the mandibular third molar overlaps or is in close proximity to the mandibular canal

Form-function relationships in dragonfly mandibles under an evolutionary perspective

© 2017 The Author(s). Functional requirements may constrain phenotypic diversification or foster it. For insect mouthparts, the quantification of the relationship between shape and function in an evolutionary framework remained largely unexplored. Here, the question of a functional influence on phenotypic diversification for dragonfly mandibles is assessed with a large-scale biomechanical analysis covering nearly all anisopteran families, using finite element analysis in combination with geometric morphometrics. A constraining effect of phylogeny could be found for shape, the mandibular mechanical advantage (MA), and certain mechanical joint parameters, while stresses and strains, the majority of joint parameters and size are influenced by shared ancestry. Furthermore, joint mechanics are correlated with neither strain nor mandibular MA and size effects have virtually play no role for shape or mechanical variation. The presence of mandibular strengthening ridges shows no phylogenetic signal except for one ridge peculiar to Libelluloidea, and ridge presence is also not correlated with each other. The results suggest that functional traits are more variable at this taxonomic level and that they are not influenced by shared ancestry. At the same time, the results contradict the widespread idea that mandibular morphology mainly reflects functional demands at least at this taxonomic level. The varying functional factors rather lead to the same mandibular performance as expressed by the MA, which suggests a many-to-one mapping of the investigated parameters onto the same narrow mandibular performance space

Effects of Oral Contraceptives on The Prevalence of Alveolar Osteitis After Mandibular Third Molar Surgery: A Retrospective Study

The objective of this study was to investigate the influence of oral contraceptives on the incidence rate of alveolar osteitis (AO) following the surgical extraction of both impacted mandibular third molars. This retrospective study reviewed the clinical records of patients who presented to the oral surgery clinic of a university school of dentistry for the extraction of impacted mandibular third molars. Using a database search, all patients were categorized by sex, age, occurrence of AO, and whether the females were taking oral contraceptives at the time of surgery. The patient was considered positive for AO if either one or both sockets developed AO. The incidence of AO among women taking oral contraceptives at the time of impacted mandibular third molar extraction differed significantly from that in the other patient groups. AO occurred in 37.9% (11/29) of females taking oral contraceptives, while only 8.9% (16/179) of females who were not taking oral contraceptives at the time of extraction developed AO. The total incidence of AO among females was 13.0% (27/208). The total incidence of AO among the 363 males and females presenting for mandibular third molar extractions was 13.8%. Females who are taking oral contraceptives at the time of impacted mandibular third molar extraction are at a higher risk of developing AO following extraction

Prosthetic Rehabilitation Following Lateral Resection of the Mandible with a Long Cantilever Implant-Supported Fixed Prosthesis: A 3-Year Clinical Report

This clinical report describes the prosthetic management of the surgical reconstruction of a patient after mandibular resection. Complete oral rehabilitation was achieved with a maxillary complete denture and a mandibular implant-supported fixed prosthesis with a custom titanium framework and a long unilateral cantilever

Coherence Filtering to Enhance the Mandibular Canal in Cone-Beam CT data

Segmenting the mandibular canal from cone beam CT data, is difficult due to low edge contrast and high image noise. We introduce 3D coherence filtering as a method to close the interrupted edges and denoise the structure of the mandibular canal. Coherence Filtering is an anisotropic non-linear tensor based diffusion algorithm for edge enhancing image filtering. We test different numerical schemes of the tensor diffusion equation, non-negative, standard discretization and also a rotation invariant scheme of Weickert [1]. Only the\ud scheme of Weickert did not blur the high spherical images frequencies on the image diagonals of our test volume. Thus this scheme is chosen to enhance the small curved mandibular canal structure. The best choice of the diffusion equation parameters c1 and c2, depends on the image noise. Coherence filtering on the CBCT-scan works well, the noise in the mandibular canal is gone and the edges are connected. Because the algorithm is tensor based it cannot deal with edge joints or splits, thus is less fit for more complex image structures

Early mandibular canine-lateral incisor transposition: case report

Purpose. The main aim of the present study is to present a case of mandibular transposition between lateral incisor and canine in a paediatric patient. Materials and methods. A fixed multibracket orthodontic treatment was performed by means of a modified welded arch as to correct the transposition and obtaining a class I functional and symmetrical occlusion, also thanks to the early diagnosis of the eruption anomaly. Results. Our case report shows that a satisfactory treatment of mandibular transpositions is obtained when detected at an early stage of the tooth development. Conclusions. The main treatment options to be taken into consideration in case of a mandibular transposition are two: correcting the transposition or aligning it leaving the dental elements in their transposed order; in both cases, the followups show a stable condition, maintained without relapses. Several factors, such as age of the patient, occlusion, aesthetics, patient’s collaboration, periodontal support and duration of treatment have to be considered as to prevent potential damage to dental elements and support appliances. The choice between the two treatment approaches for mandibular lateral incisor/canine transpositions mainly depends on the time the anomaly is detected

Comparative anchorage maintenance between the intercanine coil, lip bumper, and mandibular cervical traction during cuspid retraction

Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry, 1972 (Orthodontics)Bibliography included.The present study was undertaken to compare the efficiency of three different biomechanical mechanisms in preserving mandibular molar anchorage. Thirty-five patients were treated with intercanine coil, lip bumper, 9r mandibular cervical traction through the end of cuspid retraction. Midtreatment cephalograms were then taken. Superimposition of these midtreatment cepbalograms with the pretreatment cephalograms provided the author with the net mesial or distal movement of the mandibular first molar in each case. The data obtained from each case was accordingly placed in the appropriate biomechanical group. Each group was then statistically related to one another by means of the Mann-Whitney U Test. It was found that a stastically significant difference existed between lower cervical traction and the intercanine coil. The confidence level obtained (P < .02) indicated that less than two cases out of a hundred had a chance of coming from the same population. This data also showed a mean increase in mandibular anchorage with lower cervical traction ( +.062 mm. gained) indicating that there may be very good possibilities for this system to be used in orthodontic cases when anchorage is of a critical nature