Photoelastic Stress Analysis of Different Attachment Systems on Implant-Retained and Conventional Palatal Obturator Prostheses

Partial fixed dental prostheses fabricated using fiber-reinforced composite resin supported by short and extra-short implants: A case series

PURPOSE

This study aimed to evaluate the 10-year outcomes of partial fixed dental prostheses (P-FDPs) fabricated using metal-free fiber-reinforced composite (FRC) resin frameworks veneered with composite resin and supported by short and extra-short implants.

METHODS

This study included 28 patients with 38 FRC prostheses supported by 96 implants. Implant and prosthesis survival and success rates were evaluated using Kaplan-Meier analysis.

RESULTS

The 10-year implant survival and success rate, as determined by Kaplan-Meier analysis, was 96.9%, and the prosthesis survival and success rates were 94.7% and 92.0%, respectively. None of the parameters under investigation were significantly correlated with prosthetic survival or successful outcomes, but three parameters were correlated with higher peri-implant bone levels: implant placement in the mandible as opposed to the maxilla, shorter P-FDP spans, and natural teeth on the opposing arch.

CONCLUSIONS

FRC P-FDPs supported by short and extra-short implants presented high, up to 10-year, survival and success rates, when used to restore partially edentulous arches.

Biomechanical evaluation of spring system for implant-supported prosthesis: analysis by photoelasticity and extensometry

New systems are released in the odontological market with the objective of bringing improvements and advancements in the clinical success of implants and implant-supported prostheses. The distribution of tension for the bone/implant system of these new systems is important. The purpose of this work was to evaluate, by photoelastic analysis and strain gauges, the distribution of tension for the bone/implant system, using the Slim system. A photoelastic cast with an external hexagon implant was manufactured and a metal prosthesis was screwed below it, with or without the tested system. For the photoelasticity methodology, a photoelastic cast, with or without the tested system, was positioned in a circular polariscope, and axial loads of 100 N were applied to the centre of the crown. The pattern of tension generated was photographed and analysed qualitatively in an imaging programme. For the extensometry methodology, two extensometers were placed in the mesial and distal region of the implant in the photoelastic cast. The axial loads were applied to the group again, with or without the system (n = 10). The t test of independent samples with a significance level of 5% was used for this analysis. This study demonstrated greater tension values for both the photoelastic and extensometry methods when the tested system was used. Clinical studies must be performed to evaluate the tested system because the results might not be clinically significant to a bone reabsorption.

Stress Distribution in an Implant-Supported Mandibular Complete Denture Using Different Cantilever Lengths and Occlusal Coating Materials

PURPOSE

The aim of this study was to assess stress distribution in the bone-implant interface of a mandibular implant-supported prosthesis with different cantilever lengths, aesthetic coating materials, and implant abutments.

MATERIALS AND METHODS

A photoelastic model of an edentulous mandible, containing 5 external hexagon implants, was constructed. Experimental models were divided into 6 groups: group 1-UCLA component and metal bar; group 2-UCLA component and acrylic resin coating; group 3-UCLA component and porcelain coating; group 4-abutment and metal bar; group 5-abutment and acrylic resin coating; and group 6-abutment and porcelain coating. Forces were applied to the most anterior implant, the most posterior implant, and different cantilever lengths.

RESULTS

The results showed a higher number of high-stress fringes as the cantilever length increased. Fringes were better distributed in groups with prostheses composed of acrylic resin and in groups that contained an abutment.

CONCLUSION

The stress distribution in the bone-implant interface is improved when the cantilever is eliminated and when abutments in an acrylic resin prosthesis are used.

Photoelastic analysis to compare implant-retained and conventional obturator dentures

The use of photoelastic analysis contributes to the rehabilitation of patients with oral-sinus-nasal sequelae, which in turn affect important functions such as chewing, swallowing, and speech. The prosthetic rehabilitation with implant-retained dentures is a suitable treatment option. The purpose of this study was to verify, by using a photoelastic analysis, the stress distribution in implant-retained palatal obturator dentures (relined or not) associated with different attachment systems (O-ring, bar-clip, and bar-clip associated with distally placed O-rings). Two photoelastic models were obtained from an experimental maxillary cast presenting an oral-nasal communication. One model had two 13-mm length implants placed on the left region. A total of eight colorless maxillary obturators were fabricated and subsequently four of them were relined with soft silicone soft, and three had attachment systems associated. The assembly (model/attachment system/prosthesis) was positioned in a circular polariscope and a 100-N load was applied at 10 mm/s. The results showed that the denture relining influenced the distribution and amount of stress on the models. The O-ring group displayed the lowest stress levels, followed by bar-clip system associated with distally placed O-rings and bar-clip groups.