In vitro evaluation of conventional and locking miniplate/screw systems for the treatment of mandibular angle fractures

This in vitro study evaluated the influence of the type of miniplate and the number of screws installed in the proximal and distal segments on the stability and resistance of Champy's osteosynthesis in mandibular angle fractures. Sixty polyurethane hemimandibles with bone-like consistency were randomly assigned to four groups (n = 15) and sectioned in the mandibular angle region to simulate fracture. The bone segments were fixed by different osteosynthesis methods using 2.0 mm miniplates and 2.0 mm x 6 mm rnonocortical screws. In groups 1 and 2, two conventional (G1) or locking (G2) screws were installed in each bone segment using a conventional (G1) or a locking (02) straight miniplate; in groups 3 and 4, three conventional (03) or locking (04) screws were installed in the proximal segment and four conventional (G3) or locking (04) screws were installed in the distal segment using a conventional (G3) or a locking (G4) seven-hole straight miniplate. The hemimandibles were loaded in compressive strength until a 4 mm displacement occurred between the segments, vertically or horizontally. Locking plate/screw systems provided significantly greater resistance to displacement than conventional ones (p < .01). Locking miniplates offered more resistance than conventional miniplates. Long locking miniplates provided greater stability than short ones.

Mandibular Movement Restoration Through Bilateral Coronoidectomy by Intraoral Approach

The present study aimed at reporting a clinical and surgical case of bilateral coronoidectomy, using an intraoral approach. The patient is a 26-year-old man, who sought attendance complaining of a gradual reduction of his oral opening in the past 3 years; however, he had an aggravation in the last 2 months. After clinical examination and imaging evaluation, the diagnosis of coronoid process hyperplasia was confirmed, and the surgical treatment was proposed. Under general anesthesia, with nasotracheal intubation guided by a nasofiberendoscope, using an intraoral approach, the bilateral coronoidectomy was performed. In the immediate postoperative period, an increase of the buccal opening measured 29 mm, representing an enhancement of 11 mm, and in the 30th postoperative day, it measured 31.12 mm. During the clinical follow-up period, a reestablishment of the mandibular movements was observed. Therefore, coronoidectomy by an intraoral approach and the physiotherapy performed in the postoperative period were efficient procedures.

Patients' Satisfaction After Surgical Facial Reconstruction or After Rehabilitation With Maxillofacial Prosthesis

The matching of the aesthetic, functional, and psychosocial results of a facial deformity may produce devastating effects in its carriers, especially if the lesion is extensive or the treatment is aggressive. Because of this, the objective of the present article was to evaluate patient's satisfaction rating after surgical facial reconstruction or rehabilitation with oral and maxillofacial prosthesis, by means of reviewing the literature.

Comparison of Single-Standing or Connected Implants on Stress Distribution in Bone of Mandibular Overdentures: A Two-Dimensional Finite Element Analysis

This study aimed to compare the influence of single-standing or connected implants on stress distribution in bone of mandibular overdentures by means of two-dimensional finite element analysis. Two finite element models were designed using software (ANSYS) for 2 situations: bar-clip (BC) group-model of an edentulous mandible supporting an overdenture over 2 connected implants with BC system, and o'ring (OR) group-model of an edentulous mandible supporting an overdenture over 2 single-standing implants with OR abutments. Axial loads (100 N) were applied on either central (L1) or lateral (L2) regions of the models. Stress distribution was concentrated mostly in the cortical bone surrounding the implants. When comparing the groups, BC (L1, 52.0 MPa and L2, 74.2 MPa) showed lower first principal stress values on supporting tissue than OR (L1, 78.4 MPa and L2, 76.7 MPa). Connected implants with BC attachment were more favorable on stress distribution over peri-implant-supporting tissue for both loading conditions.

Influence of Ridge Inclination and Implant Localization on the Association of Mandibular Kennedy Class I Removable Partial Denture

The aim of this study was to evaluate the tendency of displacement of the supporting structures of the distal extension removable partial denture (DERPD) associated to the implant with different inclinations of alveolar ridge and implant localizations through a two-dimensional finite-element method. Sixteen mandibular models were fabricated, presenting horizontal, distally descending, distally ascending, or descending-ascending ridges. All models presented the left canine and were rehabilitated with conventional DERPD or implant-retained prosthesis with the ERA system. The models were obtained by the AutoCAD software and transferred to the finite-element software ANSYS 9.0 for analysis. A force of 50 N was applied on the cusp tips of the teeth, with 5 points of loading of 10 N. The results were visualized by displacement maps. For all ridge inclinations, the assembly of the DERPD with distal plate retained by an anterior implant exhibited the lowest requisition of the supporting structures. The highest tendency of displacement occurred in the model with distally ascending ridge with incisal rest. It was concluded that the association of the implant decreased the displacement of the DERPD, and the anterior positioning of the implant associated to the DERPD with the distal plate preserved the supporting structures for all ridges.

Most Frequent Tumors in Maxillofacial Area Rehabilitated Through Surgical Reconstruction and Prostheses

Cancer is regarded as the abnormal cellular multiplication; it is not controlled by the organism; and its cells present a differentiated DNA. Initially, the disease does not show clinical signs, but it can be diagnosed by laboratorial examinations. When tumors are present in the maxillofacial area, they can entail the loss of these area organs, which become responsible for the carrier's social environment exclusion. This paper aimed at showing, through a literature review, the cancers that more commonly happen in the face and the possibilities of regenerating in the patient mutilated through surgical reconstruction and prostheses.

Influence of Implant Inclination Associated With Mandibular Class I Removable Partial Denture

The aim of this study was to use two-dimensional finite element method to evaluate the displacement and stress distribution transmitted by a distal extension removable partial denture (DERPD) associated with an implant placed at different inclinations (0, 5, 15, and 30 degrees) in the second molar region of the edentulous mandible ridge. Six hemimandibular models were created: model A, only with the presence of the natural tooth 33; model B, similar to model A, with the presence of a conventional DERPD replacing the missing teeth; model C, similar to the previous model, with a straight implant (0 degrees) in the distal region of the ridge, under the denture base; model D, similar to model C, with the implant angled at 5 degrees in the mesial direction; model E, similar to model C, with the implant angled at 15 degrees in the mesial direction; and model F, similar to ME, with the implant angled at 30 degrees in the mesial direction. The models were created with the use of the AutoCAD 2000 program (Autodesk, Inc, San Rafael, CA) and processed for finite element analysis by the ANSYS 8.0 program (Swanson Analysis Systems, Houston, PA). The force applied was vertical of 50 N on each cusp tip. The results showed that the introduction of the RPD overloaded the supporting structures of the RPD and that the introduction of the implant helped to relieve the stresses of the mucosa alveolar, cortical bone, and trabecular bone. The best stress distribution occurred in model D with the implant angled at 5 degrees. The use of an implant as a support decreased the displacement of alveolar mucosa for all inclinations simulated. The stress distribution transmitted by the DERPD to the supporting structures was improved by the use of straight or slightly inclined implants. According to the displacement analysis and von Mises stress, it could be expected that straight or slightly inclined implants do not represent biomechanical risks to use.

Evaluation of Bone Insertion Level of Support Teeth in Class I Mandibular Removable Partial Denture Associated With an Osseointegrated Implant: A Study Using Finite Element Analysis

Purpose: This study evaluated the influence of distal extension removable partial denture associated with implant in cases of different bone level of abutment tooth, using 2D finite element analysis.Materials and Methods: Eight hemiarch models were simulated: model A-presenting tooth 33 and distal extension removable partial denture replacing others teeth, using distal rest connection and no bone lost; model B-similar to model A but presenting distal guide plate connection; model C-similar to model A but presenting osseointegrated implant with ERA retention system associated under prosthetic base; model D-similar to model B but presenting osseointegrated implant as described in model C; models E, F, G, and H were similar to models A, B, C, and D but presenting reduced periodontal support around tooth 33. Using ANSYS 9.0 software, the models were loaded vertically with 50 N on each cusp tip. For results, von Mises Stress Maps were plotted.Results: Maximum stress value was encountered in model G (201.023 MPa). Stress distribution was concentrated on implant and retention system. The implant/removable partial denture association decreases stress levels on alveolar mucosa for all models.Conclusions: Use of implant and ERA system decreased stress concentrations on supporting structures in all models. Use of distal guide plate decreased stress levels on abutment tooth and cortical and trabecular bone. Tooth apex of models with reduced periodontal support presented increased stress when using distal rest. (Implant Dent 2011;20:192-201)

Evaluation of the influence of location of osseointegrated implants associated with mandibular removable partial dentures

Purpose: The aim of this research was to assess, by means of, the bi-dimensional finite element method, the best implant location in the alveolar edge, through stress distribution and support structure displacement of a distal extension removable partial denture associated with an osseointegrated implant of 10.0 x .75 mm, acting as abutment for the denture base.Methods and Materials: Five models in sagittal cut were used to represent: model A-hemi arch containing natural tooth 33 and the distal alveolar edge; model B-similar to model A, but with a conventional removable partial denture to replace the absent teeth; model C (MC)-similar to the previous one, with an implant in the distal region of the edge under the denture base; model D-similar to MC, with the implant in the central region of the edge; model E-similar to MC, with an implant in the mesial region of the edge. With the aid of the finite element program ANSYS 8.0, the models were loaded with strictly vertical forces of 50 N on each cusp tip. Displacement and von Mises Maps were plotted for visualization of results.Results: The introduction of implant diminished the tendency of intrusion of the removable partial denture in all situations. The maximum stress was observed on implant in all situations. Approximating implant in direction of support teeth was benefit for stress distribution.Conclusion: Model D presented the lowest value for maximum tendency to displacement when compared with those found in the other models; model E demonstrated better relief with regard to demand from the abutment tooth; locating the implant near of the abutment tooth influenced positively the distribution of stresses on the analyzed structures.

Reconstruction of Skull Defects: Currently Available Materials

The restoration and recovery of a compromised skull continues to be a challenge to craniofacial surgeons and neurosurgeons. Different operative techniques and implant materials are being used to reconstruct the rigid framework of the skull. However, no currently available materials satisfy all of these criteria. According to this premise, the aim of this study was to report on the currently available materials for the reconstruction of the cranial vault and to describe their main characteristics, advantages, and disadvantages. Although the use of the materials discussed in this study is clearly positive for the reconstruction of skull defects and cranioplasties, there is a need for more complex studies and research into developing these materials to achieve all the ideal prerequisites stipulated by the scientific community and to evaluate their properties and aesthetic and functional results in the long term.

Management of Orbital Reconstruction

One of the concerns after a major trauma to the orbit is to be rebuilt. This can be achieved with care in management of orbital reconstruction, techniques, types of materials, and osseointegrated implants; it allows satisfactory aesthetic recuperation and well-being, whereas psychological therapy allows for patients' re-insertion in social and family environment to make them feel happier and safer.

Mesiodistal angulations of the mandibular canines, premolars and molars with or without the presence of third molars

The results show that, in both groups, the mandibular premolars and molars had enhanced angulation in the mesial direction, when compared with a control group of 42 Caucasians ranging in age from 12 to 17 years with a 'normal' occlusion (P < 0.05), while the mesiodistal axial angulation of the mandibular canines was similar to the control group (P < 0.05). The two groups, when compared, exhibited similar angular values for the canines, premolars and mandibular molars (P < 0.05), indicating no influence of the third molars.

Utilização da distração osteogênica mediana sagital para tratamento da atresia mandibular

OBJETIVO: relatar o tratamento de uma paciente com apinhamento severo decorrente de uma atresia maxilomandibular, tratada por meio da Distração Osteogênica da Sínfise Mandibular (DOSM). RESULTADOS: neste caso, observamos bom engrenamento dentário, diminuição do corredor bucal escuro, correção do apinhamento, boa forma de arcos e boa estética facial, num período de tempo bastante satisfatório, sem trazer dano ao tecido periodontal adjacente. CONCLUSÃO: pacientes com arcos atrésicos e apinhamento dentário podem ser beneficiados com a DOSM que, quando bem indicada, surge como uma nova forma de tratamento para casos limítrofes de apinhamento dentário, nos quais as alternativas convencionais oferecem limitações, tais como o achatamento do perfil facial, o aumento do corredor bucal e a instabilidade.

Distração osteogênica da sínfise mandibular como opção de tratamento ortodôntico: relato de caso

INTRODUÇÃO: o problema transversal em Ortodontia pode ser de origem dentária, esquelética ou uma combinação de ambas e pode ser tratado de várias maneiras de acordo com o tipo de tecido envolvido e o arco dentário acometido. em se tratando de um problema esquelético e maxilar, o ortodontista poderá lançar mão da disjunção ortopédica, dependendo da idade óssea, obtendo uma correção da atresia, um alinhamento dentário espontâneo resultante do aumento no perímetro do arco e um sorriso mais amplo, beneficiando esteticamente o paciente. Porém, este tratamento de disjunção mandibular se torna inviável, já que este osso tem sua sutura fusionada precocemente. A expansão neste caso é alveolar e sua estabilidade é questionada. OBJETIVO: relatar um caso clínico, apresentando uma nova alternativa de tratamento para o apinhamento inferior: a Distração Osteogênica da Sínfise Mandibular (DOSM). Neste procedimento, é feita uma osteotomia sagital na sínfise, criando-se uma sutura artificial para que uma separação óssea seja conseguida, utilizando uma mecânica com aparelho disjuntor de Hyrax modificado. RESULTADOS: os resultados do tratamento apresentado mostram uma melhora na forma do arco, diminuição do corredor bucal, correção do apinhamento dentário e também uma estabilidade do tratamento, sem dano aos tecidos adjacentes. Neste caso clínico, a DOSM se mostrou uma excelente opção de tratamento.

Utilization of autogenous bone, bioactive glasses, and calcium phosphate cement in surgical mandibular bone defects in Cebus apella monkeys

Purpose: the purpose of the present study was to evaluate the histologic results of bone cavities that were surgically created in the mandibles of Cebus apella monkeys and filled with autogenous bone, PerioGlas, FillerBone, or Bone Source. Materials and Methods: Surgical cavities 5 mm in diameter were prepared through both mandibular cortices in the mandibular angle region. The cavities were randomly filled, and the animals were divided into groups according to the material employed: Group 1 cavities were filled with autogenous corticocancellous bone; group 2 cavities were filled with calcium phosphate cement (BoneSource); and group 3 and group 4 cavities were filled with bioactive glass (FillerBone and PerioGlas, respectively). After 180 days the animals were sacrificed, and specimens were prepared following routine laboratory procedures for hematoxylin/eosin staining and histologic evaluation. Results: the histologic analysis showed that autogenous bone allowed total repair of the bone defects; bioactive glasses (FillerBone and PerioGlas) allowed total repair of the defects with intimate contact of the remaining granules and newly formed bone; and the cavities filled with calcium phosphate cement (BoneSource) were generally filled by connective fibrous tissue, and the material was almost totally resorbed. Discussion: the autogenous bone, FillerBone, and PerioGlas provided results similar to those in the current literature, showing that autogenous bone is the best Choice for filling critical-size defects. Synthetic implanted materials demonstrated biocompatibility, but the bioglasses demonstrated osteoconductive activity that did not occur with calcium phosphate (BoneSource). Conclusion: According to the methodology used in this study, it can be concluded that the utilization of autogenous bone and bioactive glasses permitted the repair of surgically created critical-size defects by newly formed bone; the synthetic implanted materials demonstrated biocompatibility, and the bioactive glasses demonstrated osteoconductive activity. The PerioGlas was mostly resorbed and replaced by bone and the remaining granules were in close contact with bone; the FillerBone showed many granules in contact with the newly formed bone; BoneSource did not permit repair of the critical-size defects, and the defects were generally filled by connective fibrous tissue.