A 3 to 4 year study of single tooth hydroxylapatite coated endosseous dental implants

Randomized, Controlled Histologic and Histomorphometric Evaluation of Implants With Nanometer-Scale Calcium Phosphate Added to the Dual Acid-Etched Surface in the Human Posterior Maxilla

BACKGROUND

Placement of dental implants in the posterior maxilla has been associated with higher rates of failure that are due, in part, to the poor bone quality of this region. The purpose of the present study was the histologic and histomorphometric evaluation of the bone around a new implant surface treatment created by a deposition of nanometer-sized calcium phosphate particles added to the dual acid-etched surface.

METHODS

One custom-made 2 x 10-mm site evaluation implant (SEI) with this novel treatment surface (test) and one SEI with the dual acid-etched surface without treatment (control) were placed in the posterior maxilla of 15 patients. All SEIs were retrieved after 2 months and evaluated under confocal laser scanning microscopy (CLSM) and by light microscopy for histomorphometric analysis of the bone-implant contact (BIC).

RESULTS

Histologic observations in control SEIs showed formation of new bone around the implant surface; however, it was not always in direct contact with the entire perimeter of the threads. The mean BIC was 19% +/- 14.2%. Test SEIs showed peri-implant bone tightly contacting the implant surface and better adapted to the threads. Three-dimensional reconstruction of sections obtained using CLSM showed the intimacy of the contact between bone and test SEI surface through the entire thickness of the specimens. The mean BIC was 32.2% +/- 18.5%.

CONCLUSIONS

After 2 months of healing, comparison of the BIC values showed a statistically significant greater mean BIC for test SEIs than for controls. The clinical implications of these results included shortening of the implant healing period and earlier loading protocols.

Biomechanical aspects of marginal bone resorption around osseointegrated implants: considerations based on a three-dimensional finite element analysis

OBJECTIVES

Although bone loss around implants is reported as a complication when it progresses uncontrolled, resorption does not always lead to implant loss, but may be the result of biomechanical adaptation to stress. To verify this hypothesis, a three-dimensional finite element analysis was performed and the influence of marginal bone resorption amount and shape on stress in the bone and implant was investigated.

MATERIAL AND METHODS

A total of nine bone models with an implant were created: a non-resorption (Base) model and eight variations, in which three different resorption depths were combined with pure vertical or conical (vertical-horizontal) resorption. Axial and buccolingual forces were applied independently to the occlusal node at the center of the superstructure.

RESULTS

Regardless of load direction, bone stresses were higher in the pure vertical resorption (A) models than in the Base model, and increased with resorption depth. However, cortical bone stress was much lower in the conical resorption models than in both the Base and A models of the same resorption depth. An opposite tendency was observed in the cancellous bone under buccolingual load. Under buccolingual load, highest stress in the implant increased linearly with the resorption depth for all the models and its location approached the void existing below the abutment screw.

CONCLUSIONS

The results of this analysis suggest that a certain amount of conical resorption may be the result of biomechanical adaptation of bone to stress. However, as bone resorption progresses, the increasing stresses in the cancellous bone and implant under lateral load may result in implant failure.

Histologic Analysis of Clinically Retrieved Immediately Loaded Titanium Implants: A Report of 11 Cases

BACKGROUND

Several investigators have reported high survival rates for early or immediately loaded dental implants.

PURPOSE

The aim of the present study was to analyze histologically the periimplant tissue reactions and the bone-titanium interface of clinically retrieved immediately loaded titanium implants.

MATERIALS AND METHODS

Eleven implants were inserted in the posterior jaw regions of six patients, serving as the most distal abutments of fixed provisional bridges and subjected to immediate occlusal loading. After a 10-month loading period, all 11 implants were retrieved with a trephine.

RESULTS

Mature bone was present at the interface of all implants. Some vertical bone loss was observed; this was more pronounced for cylindric implants. The bone-implant contact was approximately 60 to 65% for all implants.

CONCLUSIONS

The results demonstrate that osseointegration of dental implants can occur during immediate loading.