Qualitative Assessment of Reliability of Cone-beam Computed Tomography in evaluating Bone Density at Posterior Mandibular Implant Site.

Introduction: The success of dental implants depends primarily on the primary implant stability and the bone density so that predictable osseointegration can be achieved. To achieve the desired results, systematic preoperative planning for implant placement is required. The sole aim of the study was to assess the reliability of preoperative bone density of mandibular posterior region for implant placement using computerized tomography-derived bone densities in Hounsfield units (HU). Materials and methods: A total of 200 patients with 352 implant sites between 2014 and 2017 were assessed for the posterior mandibular area using cone-beam computed tomography (CBCT). Evaluation was done by two experienced observers independently. Results: The mean bone density of males was 690.5 ± 104.12 HU and in females, it was 580.20 ± 120.2 HU. Overall, 21% of sites were of low bone density, 39.5% were of intermediate density, and 39.4% were of high density. Receiver operating characteristic (ROC) analysis presented that the CBCT intensity values had a high predictive power for predicting both high-density sites and intermediate-density sites. Conclusion: We can say from our results that, for predicting the bone densities in posterior mandible for determining implant sites, so as to achieve best osseointegration, CBCT values can be reliably used. Clinical significance: It has been proved that bone density and implant stability are dependent on each other and osseointegration is important for the success of treatment. With advancements in dentistry and introduction of CBCT, treatment planning and prediction of appropriate implant sites could be made easy and more predictable. Thus, we can say that CBCT can be considered an alternative diagnostic tool for the bone density evaluation during treatment planning for implant placement. Keywords: Bone density, Cone-beam computed tomography, Implants, Osseointegration.

To Assess and Evaluate the Variation of Mandibular Anatomy Using Cone Beam Computed Tomography Before Planning an Implant Surgery: A Population-based Retrospective Study.

AIM: The accurate placement of implants in mandible requires consideration for angulations of the bone along with the vertical dimensions. The aim of this present study was to assess the variation of mandibular anatomy using computed tomography (CT) radiography and to evaluate the effect of presence and absence of teeth on the mandibular anatomy before planning an implant surgery. MATERIALS AND METHODS: The present population-based retrospective study was conducted using 167 digital CT scan images those selected from departmental archives. The samples were sub-divided two groups: group 1included digital CT of edentulous mandible while group 2 included digital CT of edentulous mandible. The axial height, vertical height, and angulations were recorded separately for each group. RESULTS: The results of the present study showed a gradual increase in mandibular angle in both the groups with a statistically significant difference only in the canine-premolar area. The axial height showed a significant difference at canine and first premolar area and a second premolar and the first molar area. However, available height showed a significant difference in canine and first premolar area and distal to the second molar area. When both the sides were compared, no statistically significant difference was observed between right and left sides. CONCLUSION: It was concluded that due to the variability of the mandibular anatomy and because of the effects of various imperative factors, 3D imaging like CT scans should be recommended for safer and secure presurgical planning. CLINICAL SIGNIFICANCE: In surgical osteotomies and implant placement especially in post-extraction sockets, two-dimensional (2D) image of panoramic radiographs should not be considered that reliable as these three-dimensional (3D) imaging radiographs. Therefore CT scans of various angulations and sections must be considered by the clinicians to rationally study the mandibular anatomy and their risk associated areas.

Modification of existed prosthesis into a flexible wall hollow bulb obturator by permanent silicone soft liner for a hemimaxillectomy patient with restricted mouth opening.

PATIENT: A patient of hemimaxillectomy with restricted mouth opening, wearing a hard acrylic bulb obturator encountered difficulty in insertion and removal of the prosthesis. The prosthesis was converted into a open hollow bulb obturator with flexible walls with permanent silicone soft liner for easy insertion and removal. DISCUSSION: Patients having acquired maxillary defects due to surgical resection of the maxilla often suffer with difficulty in mastication, swallowing, nasal regurgitation, speech disturbances and poor esthetics. Different types of obturator with various bulb designs most commonly fabricated from acrylic resins together with "acrylic resin plate and/or" metal framework are used to improve the quality of life of these patients by restoring the function. But restricted mouth opening in some of these patients makes it difficult to place and remove the prosthesis with hard acrylic bulb. Fabrication of flexible open hollow bulb and relining of remaining obturator with resilient permanent silicone soft liner makes easy insertion and removal of the prosthesis and also improve the retention by intimate contact of soft liner with the tissues. CONCLUSION: Permanent silicone soft liner open hollow bulb obturator is a novel way for the functional rehabilitation of a hemimaxillectomy patient suffering with restricted mouth opening.