In Vitro Evaluation of the Primary Stability of Short Implants in Different Surgical Techniques.

PURPOSE: This study was designed to evaluate the effects of four different surgical techniques on the primary stability of short implants in two sizes (4-mm and 6-mm length) through resonance frequency analysis and insertion torque measurement in vitro. MATERIALS AND METHODS: Forty implant site preparations and implant insertions were performed in pig ribs. Guided surgery, bone condensing, conventional drilling, and undersized preparation surgical techniques were used five times in each bone block to prepare 4-mm/6-mm-length implant beds. The maximum insertion torque and implant stability quotient (ISQ) values were recorded for each implant. RESULTS: Both the ISQ and torque differed significantly for various surgical techniques (P = .009 and P < .001). The conventional technique had higher ISQ (79.00), whereas the condenser technique had higher torque (48.00 Ncm) than did the other techniques. The mean torque was significantly higher in all surgical techniques other than the guided surgery group regardless of implant length (P < .01 for all). Implant lengths were not significantly different in terms of ISQ and torque in all surgical techniques. CONCLUSION: There are significant correlations between the implant bed preparation technique and primary implant stability when using short implants. Conventional surgery and the bone condensing technique are favorable alternatives with higher primary stability and torque values in short implants.

The effects of first premolar extractions on third molar angulations.

The purpose of this study was to determine the relationship between the inclinations of second and third molars during a two- to 2.5-year period in patients treated orthodontically both with and without premolar extractions. Records of 37 first premolar extraction patients and 33 nonextraction patients were examined. The pretreatment and posttreatment panoramic radiographs were analyzed. The angles were measured between the long axis of the third molar and the occlusal plane and between the long axis of the third molar and the long axis of the second molar. Changes in third molar angulations from pretreatment to posttreatment for two groups were compared by Mann-Whitney U-test. Statistical analysis revealed that mandibular third molars showed an improvement in angulation relative to the occlusal plane in the first premolar extraction group.