ABSTRACT
Abstract Objective To quantify the bone volume that can be safely withdrawn from 3 donor sites: (1) the mandibular symphysis, (2) the oblique mandibular line and (3) the skullcap.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.
Subject(s)
Humans , Male , Female , Adolescent , Adult , Middle Aged , Aged , Skull/transplantation , Bone Transplantation/methods , Cone-Beam Computed Tomography/methods , Transplant Donor Site , Mandible/transplantation , Skull/diagnostic imaging , Retrospective Studies , Anatomic Landmarks , Transplant Donor Site/diagnostic imaging , Cortical Bone/transplantation , Cortical Bone/diagnostic imaging , Mandible/diagnostic imaging , Medical IllustrationABSTRACT
SUMMARY: The aim of this study was to ascertain the distance from the mandibular canal to the lateral, medial and upper zones of the mandibular ramus in order to identify safety margins that reduce the risk of nerve injuries in the process of removing a bone graft. A descriptive study was conducted, analyzing bilaterally 20 CBCT exams from different patients, taking measurements at 4 points in the central, lateral and medial areas of the corresponding mandibular ramus, which was located at a distance of 5 mm between each line, starting at the distal point of the second molar. Forty hemimandibles were included in this study, estimating a vertical distance for the 4 points of analysis, from between 16 and 17 mm, a distance laterally of 5 mm approximately and medially approximately from 3 to 3.9 mm; the lateral zone was significantly larger than the medial zone. It is estimated that the maximum achievement of a bone block from the area posterior to the second molar must be 13 mm deep and 3 mm laterally to minimize the risks of injuries to the inferior alveolar neurovascular bundle.
RESUMEN: El objetivo de esta investigación fue conocer la distancia que existe desde el canal mandibular a la zona lateral, medial y a la zona superior de la rama mandibular a fin de identificar márgenes de seguridad que minimicen el riesgo de lesiones nerviosas en el proceso de retiro de un injerto óseo. Se realizó un estudio descriptivo, analizando bilateralmente 20 exámenes CBCT de pacientes distintos, realizando mediciones en 4 puntos de la zona central, lateral y medial de la rama mandibular correspondiente, los cuales fueron ubicados con distancia de 5 mm entre cada línea, iniciando en el punto distal del segundo molar. Cuarenta hemimandíbulas fueron incluidas en esta investigación, estimando una distancia vertical, para los 4 puntos de análisis, de entre 16 y 17 mm, una distancia hacia lateral de 5 mm aproximadamente y hacia medial aproximadamente de 3 a 3,9 mm; la zona lateral fue significativamente mas grande que la zona medial. Se estima, que la obtención máxima de un bloque óseo desde la zona posterior al segundo molar debe ser con 13 mm de profundidad y 3 mm desde lateral para minimizar los riesgos de lesiones al paquete neurovascular alveolar inferior.