ABSTRACT
The physiologically mobile natural tooth and rigidly fixed dental implant causes different distribution of stress when connected in prosthesis and nonrigid connector compensates this. Understanding of biomechanical behavior is necessary for an adequate choice and construction of this type of rehabilitation. However, there has been insufficient research focusing on different location and type of the nonrigid connector related with the prognosis of both implant and the tooth. Aim of the Study: The purpose of this finite element (FE) analysis was to evaluate the stress distribution around bone, implant, and tooth in tooth implant fixed prosthesis under static load with variations in design and location of nonrigid connectors under simulated functional loads. Materials and Method: Three, 3-dimensional FE models connecting tooth and implant were constructed with different location and type of nonrigid connector. Simulated occlusal load was applied on the restorations and stresses developed in the supporting structures were monitored. Results: The highest stresses were found around the implant in model with nonrigid connector placed between the tooth and implant and model with modified nonrigid connector. On the other hand, less stress was noted around the implant where nonrigid connector was placed between the implant and pontic. Conclusion: It is advisable to place the nonrigid connector between the implant and the pontic to protect the implant from torque effects in a tooth implant fixed prosthesis.
ABSTRACT
Background: Insertion of the intraoral prosthesis causes deflection of the tongue, soft palate affecting the patency of the airway. Aims: To evaluate the cephalometric soft tissue variation in tongue, soft palate, and its effect on posterior airway space in edentulous patients with the insertion of the denture. Settings and Design: Randomized controlled trial. Materials and Methods: Complete denture (CD) prosthesis was fabricated for first time denture wearers comprising 22 males and 18 females within the age range of 50–65 years. Lateral skull radiographs were taken for each of the subjects in their resting position without CDs (T0), with CDs (T1) at least 1‑week postinsertion and after 6 months of usage (T2), respectively. The reference points, lines, and angles on the cephalometric films were used to evaluate the position or inclination of the head, variations in tongue position and length, the changes in the anteroposterior dimension of the soft palate, and posterior airway space variations. Intra‑investigator error variance was not found to be statistically significant (P < 0.05). Statistical Analysis Used: Using Statistical Package for the Social Sciences (SPSS) v16.0 the significant difference in the paired samples (without CD and with CD) was found using the paired t‑test. The probability value P = 0.05 is considered as a significant level. Results: On comparison of T1 and T0, the heads were more extended with the downward position of the tongue with an increase in its length and the posterior airway space was decreased in T1. Significant differences in values were not observed between T1 and T2. Conclusions: With CDs, the change in airway space was related to alteration in soft palate and tongue dimension. There were no changes in dimension at 6 months follow‑up.