Photoelastic stress analysis of implants according to fixture design / 대한치과보철학회지

PURPOSE: The purpose of this study was to evaluate the pattern and the magnitude of stress distribution in the supporting tissues surrounding three different types of implants(ITI, 3i, and Bicon implant system). MATERIAL AND METHOD: Photoelastic models were made with PL-2 resin(Measurements Group, Raleigh, USA) and three implants of each kind were placed in the mandibular posterior edentulous area distal to the canine . For non-splinted restorations, individual crowns were fabricated on three titanium abutments. For splinted restorations, 3-unit fixed partial dentures were fabricated. Photoelastic stress analyses were carried out to measure the fringe order around the implant supporting structure under simulated loaded conditions(15 lb, 30 lb). CONCLUSION: The results were as follows; 1. Regardless of the implant design, stresses were increased in the apex region of loaded implant when non-splinted restorations were loaded. While relatively even stress distribution occurred with splinted restorations. Splinting was effective in the second implant. 2. Strain around Bicon implant were lower than those of other implants, which confirmed the splinting effect. The higher the load, the more the stress occurred in supporting tissue, which was most obvious in the Bicon system. 3. Stress distribution in the supporting tissue was favorable in the ITI system, while the other side of 3i system tended to concentrate the stress in some parts.

Photoelastic stress analysis of implants according to fixture design / 대한치과보철학회지

PURPOSE: The purpose of this study was to evaluate the pattern and the magnitude of stress distribution in the supporting tissues surrounding three different types of implants(ITI, 3i, and Bicon implant system). MATERIAL AND METHOD: Photoelastic models were made with PL-2 resin(Measurements Group, Raleigh, USA) and three implants of each kind were placed in the mandibular posterior edentulous area distal to the canine . For non-splinted restorations, individual crowns were fabricated on three titanium abutments. For splinted restorations, 3-unit fixed partial dentures were fabricated. Photoelastic stress analyses were carried out to measure the fringe order around the implant supporting structure under simulated loaded conditions(15 lb, 30 lb). CONCLUSION: The results were as follows; 1. Regardless of the implant design, stresses were increased in the apex region of loaded implant when non-splinted restorations were loaded. While relatively even stress distribution occurred with splinted restorations. Splinting was effective in the second implant. 2. Strain around Bicon implant were lower than those of other implants, which confirmed the splinting effect. The higher the load, the more the stress occurred in supporting tissue, which was most obvious in the Bicon system. 3. Stress distribution in the supporting tissue was favorable in the ITI system, while the other side of 3i system tended to concentrate the stress in some parts.

Effects of Release of Tip Supporting Fibrous Tissues for Short Nose Correction

A short nose is one that extends less than one third of the vertical height of the face or whose distance from nasion to tip-defining point is short. Lengthening short noses has been regarded as one of the most challenging and at times vexing tasks in secondary nasal surgery. For correction of short nose, nasal tip supporting tissues from alar cartilages are released and nasal tip is positioned and fixed again. There are five important nasal tip supporting tissues, fibrous connection between upper lateral cartilage and lower lateral cartilage, hinge region(fibrous connection between lateral border of lateral crus and pyriform aperture), interdormal attachment to anterior septal angle (fibrous tissue between anterior septal angle and middle crus), fibrous connection between septum and foot plate of medial crus and dermocartilaginous ligament. This study is to find out which one of the five nasal tip supporting tissues is the most important in short nose correction except dermocartilaginous ligament which has to be released during rhinoplasty. We dissected ten noses from ten fresh cadavers. Five were male and five were female with an average age of sixty three for all ten. We measured the distance between anterior septal angle and tip-defining point in every step of soft tissue dissection releasing the alar cartilage and mucosa, that are often released in short nose corrections and caudally pulling them to the direction of tip-defining point. First, distances were measured in resting and in pulling of alar cartilage. Further, changed distance were measured after releasing nasal tip supporting tissues beginning from the dissection of soft tissues between lateral crus and upper lateral cartilage to that of mucoperichondrium underneath upper lateral cartilage and septal mucoperichondrium. In each process, we found the average and standard variation, confirmed effects of those values to the lengthening of short noses. Dissecting upper lateral cartilage and lateral crus of alar cartilage was most effective in short nose correction. We also found it effective to release the hinge area and dissect the mucoperichondrium under upper lateral cartilage in lengthening the short noses.