Evaluation of bone availability for grafts in different donor sites, through computed tomography

Abstract Objective To quantify the bone volume that can be safely withdrawn from 3 donor sites: (1) the mandibular symphysis, (2) the oblique mandibular line and (3) the skullcap. Methodology For the symphysis, 200 tomographic exams were evaluated by the extension of the anterior loop of mental foramen, by the nerve, by the distance of the foramens, by the distance between the vestibular cortical and the lingual plates and by the distance between the apexes, or lower anterior teeth, and the mandibular base, using the "distance" tool of the I-CAT Vision, in the panoramic and parasagittal reformations. For the oblique line, 70 TCFC exams were analyzed retrospectively in panoramic and parasagittal reformations, evaluating the thickness of the vestibular cortical and the distance between the cortical and the mandibular canal. For the cranial bone, a hexagonal donor site located in parietal area was considered. Results The average dimensions of the bone blocks that can be safely removed from the region of the mandibular symphysis are: 32.27 mm in length, 4.87 mm in height and 4 mm in thickness, providing a volume of 628.61 mm3 available for grafting. In the oblique line, the available bone volume for grafting was 859.61 mm3. In the region of the cranial vault, multiplying the average bone thickness by the area of the hexagon, an average volume of 2,499 mm3 was obtained. Conclusions Comparing the donor sites, the bone availability in the cranial vault is 3 times greater than in the mandibular posterior region, and at least 2 times greater than in the mandibular symphysis.

Horizontal Bone Reconstruction on sites with different amounts of native bone: a retrospective study

Abstract: The lack of guidelines for bone augmentation procedures might compromise decision making in implantology. The objective of this study was to perform a retrospective study to verify the outcomes of horizontal bone reconstruction in implant dentistry with different types of materials and amounts of native bone in the recipient bed to allow for a new guideline for horizontal bone reconstruction. One hundred preoperative CT scans were retrospectively evaluated and categorized in accordance to horizontal bone defects as presence (Group P) or absence (Group A) of cancellous bone in the recipient bed. Different approaches were used to treat the edentulous ridge and the outcomes were defined either as satisfactory or unsatisfactory regarding the possibility of implant placement. The percentage distribution of the patients according to the presence or absence of cancellous bone was 92% for Group P and 8% for Group A. In Group P, 98% of the patients had satisfactory outcomes, and the use of autografts had 100% of satisfactory outcomes in this group. In Group A, 37.5% of the patients had satisfactory outcomes, and the use of autografts also yielded 100% of satisfactory outcomes. The use of allografts and xenografts in Group A had 0% and 33.3% of satisfactory outcomes, respectively. Therefore, it seems reasonable to speculate that the presence of cancellous bone might be predictive and predictable when the decision includes bone substitutes. In cases of absence of cancellous bone in the recipient bed, the use of a vitalized graft seems to be mandatory.

Correlation of Fractal Dimension with Histomorphometry in Maxillary Sinus Lifting Using Autogenous Bone Graft

The aim of this study was to determine the pattern of bone remodeling after maxillary sinus lifting in humans by means of fractal dimension (FD) and histomorphometric analysis. Therefore, the correlation between FD and the histomorphometric findings was evaluated. Sixteen patients with posterior edentulous maxilla were enrolled in this study. Maxillary sinus lifting was performed using autogenous bone grafted from the mandibular retromolar area. Three direct digital panoramic radiographs were obtained: before surgery (Group 1), immediately postoperatively (Group 2) and after 6 months of healing (Group 3) for FD analysis. Biopsies were taken after 6 months, processed and submitted to histological and histomorphometric analysis. Data were analyzed by Shapiro-Wilk test and ANOVA test followed by a Tukey test (a=0.05). The bone volume fraction of newly trabecular bone (TB) and medullary area (MA) was measured as 62.75%±17.16% and 37.25±17.16%, respectively. Significant difference in FD analysis was measured between Group 1 and Group 3. No significant difference was found in the correlation between FD and histomorphometric analysis for TB and MA (p=0.84). In conclusion, all performed analyses were effective in assessing the bone-remodeling pattern in the maxillary sinus, offering complementary information about healing and predictable outcomes. There were no correlations between FD and histomorphometric analysis.

O objetivo deste estudo foi determinar o padrão de remodelação óssea após levantamento de seio maxilar in humanos por meio de analise de dimensão fractal (FD) e histomorfometria. Além disso, a correlação entre FD e histomorfometria foi avaliada. Dezesseis pacientes com edentulismo na região posterior da maxila foram relacionados para este estudo. Levantamento de seio maxilar foi realizado utilizando-se enxerto de osso autógeno coletado da região retro molar da mandíbula. Três radiografias panorâmicas digitais foram obtidas: antes da cirurgia (Grupo 1), imediatamente após o levantamento de seio (Grupo 2) e após 6 meses de cicatrização (Grupo 3) para analise de FD. Biopsias foram coletadas após 6 meses, processadas e submetidas para analise histológica e histomorfométrica. Os dados foram analisados utilizando-se o teste Shapiro-Wilk e ANOVA seguido pelo pós teste de Tukey (a=0.05). A fração de volume de ósseo neoformado para o osso trabecular (TB) e para a área medular (MA) foi mensurado como 65,75%±17,16% and 37,25±17,16%, respectivamente. Diferença significante na analise FD foi observada entre os grupos 1 e 3. Nenhuma diferença estatística foi encontrada para correlação entre FD e histomorfometria para TB e MA (p=0,84). Em conclusão, todas as análises realizadas foram efetivas em acessar o padrão de remodelação ósseo no seio maxilar, oferecendo informações complementares sobre cicatrização e previsibilidade de resultados. Não houve correlação entre FD e histomorfometria.

Reconstrução mandibular utilizando calota craniana para reabilitação implantossuportada / Mandible reconstruction with calvarial bone graft to implant-supported rehabilitation

A perda dos dentes, juntamente com a utilização de próteses mucossuportadas, por longos períodos de tempos, podem causar reabsorção óssea levando à perda de volume e má qualidade óssea, diminuindo o sucesso na instalação de implantes. Foi realizada reconstrução de mandíbula atrófica com enxerto retirado da calota craniana e reabilitação protética sobreimplantes. A técnica utilizada mostrou ser adequada para reabilitar defeitos extensos em rebordos alveolares edêntulos que requerem grande quantidade óssea, pois apresentou osso em qualidade e quantidade ósseas suficientes com mínima reabsorção no período pós-operatório, preenchendo todos os quesitos funcionais e devolvendo a estética ao paciente.

Tooth loss and long-time wear of mucous-supported removable partial prostheses cause bone resorption leading to volume loss and poor bone quality, diminishing implant success. A case of reconstruction of atrophic mandible with calvarial bone graft and subsequent implant-supported prosthesis is presented. The technique was successfully performed, resulting in adequate rehabilitation of large defects in edentulous jaws that require large amounts of alveolar bone, showed sufficient bone quantity and quality with minimal resorption during the postoperative period, improving function and retrieving esthetics.

Sitios donantes mandibulares en implantología: una evaluación clínica / Mandibular donor areas in implantology: a clinical evaluation

La reconstrucción de rebordes alveolares atróficos para la rehabilitación con implantes oseointegrados son procedimientos que han demostrado predictibilidad en términos de estabilidad y estética. Diferentes materiales se han utilizados pero, sin duda, son los autoinjertos los que más frecuentemente se asocian al éxito terapéutico. De ellos, el hueso obtenido de sitios donantes intraorales son de elección cuando el defecto está de acuerdo al tamaño del injerto obtenido. El objetivo del presente estudio es evaluar las técnicas quirúrgicas para recolección de hueso de mandíbula y discutir las características generales y particulares asociadas a estos procedimientos quirúrgicos.

Reconstruction of atrophic alveolar ridge for rehabilitation with osseointegrated implants is a predictable procedure that offers excellent esthetic and stable results. Several materials have been used, but autogenous bone grafts continue to be the ones associated with high success rates. Depending on the size of the defect, intrabucal areas are the best donor sites for reconstruction. The aim of this study is to evaluate surgical techniques to collect bone from the jaws and discuss the general characteristics as well as the particularities associated with this type of surgical procedure.

Enxerto autógeno de sínfise mandibular / Autogenous mandibular bone grafts

Implantes osseointegrados são uma opção de tratamento e restabelecem as funções mastigatória, estética e fonética, proporcionando bem estar ao paciente. Em situações de reabsorção óssea, procedimentos cirúrgicos prévios de enxerto ósseo podem melhorar o resultado final. Dependendo das condições do local receptor, o aumento substancial da forma desejada é algumas vezes, muito difícil, devido à absorção ou deformação do material enxertado. Daí a necessidade de se avaliar bem o material de escolha, para se realizar o enxerto. Dos substitutos ósseos atualmente disponíveis, o enxerto autógeno tem se mostrado como o mais efetivo. O presente artigo relata uma técnica cirúrgica de enxerto ósseo autógeno em que a remoção do osso é feita da região da sínfese mandibular, e doado para pré-maxila, com o objetivo de sanar a deficiência óssea local, permitindo a posterior instalação de implantes e confecção protética.

Modelo experimental para la medición de radiación dispersa con y sin interposición de una barrera de titanio placa de reconstrucción mandibular / Experimental model for the measurement of dispersed radiation with and without interposition of a barrier of titanium plate of maxillary reconstruction

El objetivo de este trabajo fue comparar en un simulador físico (Alderson Rando) las variaciones que sufre el haz de radiación cobalto 60,6 MeV y 18 MeV con y sin la interposición de una barrera de titanio (Placa de reconstrucción mandibular) por medio de dosímetros termoluminoscentes tipo Lif:MgTi, con el fin de observar las modificaciones de acuerdo a la posición de los dosímetros y a los diferentes tipos de radiación.