Radiographic evaluation of anatomical variables in maxilla and mandible in relation to dental implant placement.

Introduction: Oral rehabilitation using implants is rapidly replacing tooth supported prostheses. The success of implants is largely dependent on the quality and quantity of alveolar bone. In this study, we assessed the location of limiting anatomical structures and the amount of alveolar bone available for implant placement. Materials and Method: Six hundred digital panoramic radiographs (300 males and 300 females) of dentate patients aged between 15-60 years were selected from the archives. The radiographs were subdivided into 3 groups with age interval of 15 years. Then the location of mental foramen, anterior loop, mandibular canal and maxillary sinus was determined. The amount of bone available was measured in both maxilla and mandible in the premolar and molar regions. Results: The mental foramen was most commonly located at the apex of the second premolar in both the genders. The anterior loop was more readily visible in the younger age group. The amount of bone available in the premolar and molar region of the mandible is nearly the same, while more bone is available in the premolar region of the maxilla. Conclusion: The location and morphology of anatomical structures of the jaws vary not only in different populations but also within the same population. The amount of bone available also showed variations in the same population and in the same individual on the right and left sides. The limiting anatomical structures govern the amount of bone available for possible implant placement.

Influence of different abutment diameter of implants on the peri‑implant stress in the crestal bone: A Three‑dimensional finite element analysis ‑ In vitro study.

Purpose of the Study: The study was designed to evaluate and compare stress distribution in transcortical section of bone with normal abutment and platform switched abutment under vertical and oblique forces in posterior mandible region. Materials and Methods: A three‑dimensional finite element model was designed using ANSYS 13.0 software. The type of bone selection for the model was made of type II mandibular bone, having cortical bone thickness ranging from 0.595 mm to 1.515 mm with the crestal region measuring 1.5 mm surrounding dense trabecular bone. The implant will be modulated at 5 mm restorative platform and tapering down to 4.5 mm wide at the threads, 13 mm long with an abutment 3 mm in height. The models will be designed for two situations: (1) An implant with a 5 mm diameter abutment representing a standard platform in the posterior mandible region. (2) An implant with a 4.5 mm diameter abutment representing platform switching in the posterior mandible region. Force application was performed in both oblique and vertical conditions using 100 N as a representative masticatory force. For oblique loading, a force of 100 N was applied at 15° from the vertical axis. von Mises stress analysis was evaluated. Results: The results of the study showed cortical stress in the conventional and platform switching model under oblique forces were 59.329 MPa and 39.952 MPa, respectively. Cortical stress in the conventional and platform switching model under vertical forces was 13.914 MPa and 12.793 MPa, respectively. Conclusion: Results from this study showed the platform switched abutment led to relative decrease in von Mises stress in transcortical section of bone compared to normal abutment under vertical and oblique forces in posterior mandible region.

Technique to assess the alveolar bone width for immediate implant placement in fresh extraction sockets.

Aim: To determine labial and lingual plate width at extraction site, using extracted tooth. Materials and Methods: Pre-extraction ridge mapping and arch impression using putty consistency elastomeric impression material is recorded, followed by atraumatic tooth extraction, extracted tooth is cleaned and reoriented in the earlier recorded elastomeric putty impression. The cast obtained is used to measure bone width. Results: The amount of available labial and palatal bone of an extracted socket can be assessed accurately. Conclusion: This technique will help the surgeon understand the thickness of labial plate especially the apical region without reflecting the flap, also aid in selection of proper dimension of dental implant, and if bone graft is needed.

Need of implant dentistry at undergraduate dental curriculum in Indian dental colleges.

Edentulism is the major problem in the developing countries, and is widely spread in the current population, although the prevalence is declining and incidence of tooth loss is decreasing in the developed nations. The prevalence of edentulism in India varies from 60% to 69% of 25 years and above age group. It is obvious that the number of lost teeth increases with age leading to an increase in prevalence of partially edentulous patients. From a biological point of view, the replacement of a single missing tooth with an implant rather than a three-unit fixed partial denture, and the implant-supported complete denture has been proved more efficient in improving the mastication and maintaining the bone for a longer time and also more cost-effective treatment. Many dental schools throughout Europe and America have to a various extent introduced implant dentistry as part of the compulsory undergraduate curriculum. Thus, it becomes more essential to introduce implant dentistry at undergraduate level in Indian dental schools to manage the higher percentage of edentulism.

Effect of microwave postpolymerization treatment on residual monomer content and the flexural strength of autopolymerizing reline resin.

Background : Microwave postpolymerization has been suggested as a method to improve the flexural strength of an autopolymerizing denture reline resin. However, the effect of microwave postpolymerization on the residual monomer content and its influence on flexural strength have not been investigated. Objectives : This study analyzed the effect of microwave postpolymerization on the residual monomer content and its influence on the flexural strength of an autopolymerizing reline resin (Denture Liner). Materials and Methods : A total of 70 specimens (64 Χ 10 Χ 3.3 mm) were polymerized according to the manufacturer's instructions and divided into 7 groups (n = 10). Control group specimens were not subjectedto any further processing. Before testing, the specimens were subjected to postpolymerization in a microwave oven using different power (550 and 650 W) and time (3, 4, and 5 min) settings. Two specimens of each group were then manually ground into fine powder and samples extracted from the specimens using reflux method. The samples were then subjected to gas chromatography for residual monomer determination in area%. Eight specimens were subjected to a three-point bending device with a span of 50 mm and crosshead speed of 5 mm/min, and the flexural strength was determined in MPa. Data analyses included Student's t-test and one-way analysis of variance. Results : For the Denture Liner reline resin, the residual monomer content decreased and the flexural strength increased significantly with the application of microwave irradiation using different time/power combinations. The specimens with the lowest residual monomer content were the similar specimens which presented with the highest flexural strength. Conclusion : Microwave postpolymerization irradiation can be an effective method for increasing the flexural strength of denture liner (at 650 W for 5 min) by reducing the residual monomer content by further polymerization at free radical sites.