Evaluation of two interforaminal implants and implant-assisted removable dentures on stress distribution: an in vitro study.

OBJECTIVES: In mandibular edentulism, the treatment option with a two-interforaminal implant-retained bridge and a removable partial denture is rarely evaluated in literature. The aim of this in vitro study was to evaluate the stress distribution of this treatment option by comparing it with traditional treatment options with interforaminal implants in the edentulous mandible. MATERIALS AND METHODS: Two interforaminal implants were placed in a formalin-fixed cadaver mandible, and overdentures with three different types of attachments were fabricated: (1) two ball attachments and an overdenture, (2) a Dolder bar and an overdenture, and (3) screw-retained two-implant inter-canine porcelain fused to a metal bridge and an implant-assisted removable denture (IARD) with precision attachments. Three biting conditions were generated for each denture type, and the strains were documented under vertical loading of 100 N. RESULTS: The calculated strain values from measured strains in all measurement sites and loading conditions for the screw-retained two-implant inter-canine porcelain fused to a metal bridge and a cast framework partial denture with precision attachments situation were lower than in the other scenarios (P<0.05). CONCLUSION: Within the limitations of the present study, it can be concluded that an IARD may be a reasonable and valuable alternative to ball attachments or a bar in two interforaminal implants, especially when the patients prefer to be able to show their teeth even when they take out their removable dentures.

The comparison of the precision of different dental radiographic methods in mandibular peri-implantary measurements: an in vitro study.

PURPOSE: The objective of this in vitro study was to investigate and compare the precisions of several radiodiagnostic methods used in dentistry for the measurement of peri-implantary sites. MATERIALS AND METHODS: Six dental implants were placed in a human cadaver mandible. Periapical radiographs obtained with the parallel as well as the bisecting angle technique, digital and conventional panoramic radiographs were used for implant and peri-implant bone measurements. The measurement results at each implant were statistically analyzed. RESULTS: The ICC values for the inter-observer reliability were 0.79 for implant diameters and 0.96 for implant lengths. Statistical significance was not detected between the differences of the measurements of the 2 examiners from the original implant dimensions related to anatomic locations. For both of the examiner measurements, significantly less difference from the original implant dimensions was detected in the parallel technique compared to the other techniques (p<0.05). CONCLUSION: The present study showed that the most precise peri-implant bone measurements can be obtained from periapical radiographies by using the parallel technique.

Effect of attachment types and number of implants supporting mandibular overdentures on stress distribution: a computed tomography-based 3D finite element analysis.

The objective of this study was to calculate stresses in bone tissue surrounding uncoupled and splinted implants that are induced by a bite force applied to the mandible and to determine whether the number of mandibular overdenture supporting implants in mandibular bone influence the stress distribution. A human adult edentulous mandible retrieved from a formalin fixed cadaver was used to define the geometry of finite element (FE) model and the FE model was verified with experimental measurements. Following the FE model validation, three different biting situations were simulated for the 2-, 3- and 4-implant retentive anchor as well as bar attachment overdentures under vertical loading of 100 N. As a result of the analyses, it was concluded that an increment in implant number and the splinted attachment type tended to cause lower stresses and the use of two single attachments seems to be a safe and sufficient solution for the treatment of mandibular edentulism with overdentures.

The influence of the attachment type and implant number supporting mandibular overdentures on stress distribution: an in vitro study, part I.

OBJECTIVES: The main goal of this study was to compare the stress distribution of mandibular overdentures (OVD) with different numbers of supporting implants and single versus splinted attachment types. MATERIALS AND METHODS: Four different biting situations were simulated for the 2-, 3-, and 4-implant retentive anchor as well as bar attachment OVDs on a formalin-fixed cadaver mandible, and strains were recorded under vertical loading of 100 N. RESULTS: The calculated von Mises values from measured strains in all measurement sites and loading conditions for nonsplinted attachments (retentive anchor) were higher than splinted (bar) attachments. CONCLUSIONS: It may be concluded that in cases with low quality and quantity of bone, the increase in number of implants and the use of a splinted attachment should be preferred to reduce forces emerging around the implants during function. The use of 2 single attachments in cases with good bone quality and ideal size implants still seems to be a safe and sufficient solution for the treatment of mandibular edentulism with OVDs.