Influence of metal artifacts on in vivo micro-CT for orthodontic mini-implants.

This study aimed to show the effects of metal artifacts on the in vivo micro-CT of mini-implants by measuring bone volume. We drilled a hole in the cortical bone of a rat tibia and embedded a titanium orthodontic mini-implant (diameter, 1.5 mm) in the hole. Twelve individually weighed hydroxyapatite grains (HA grains) were placed around the implant either by one dentist (method 1) or separately by 12 dentists (method 2). In vivo micro-CT was used to scan the model after placement of each grain to measure increases and decreases in bone volume voxel number. The subtracted bone voxel volume increased with HA weight in both methods. Simple linear regression analysis showed a significant correlation between weight and volume in both methods (method 1: regression coefficient: 516.502, P < 0.05; method 2: regression coefficient: 4837.432, P < 0.05). Metal artifacts did not appear to influence measurements of bone volume, although further studies are required to determine the effect of thicker implants.

An image-guided technique for puncture of the superior temporomandibular joint cavity: clinical comparison with the conventional puncture technique.

OBJECTIVE: The objective of this study was to compare an image-guided puncture technique (IGPT) with conventional puncture technique (CPT) with respect to accuracy of needle entry, maximal mouth opening, and pain in pumping manipulation treatment of internal derangement of the temporomandibular joint (TMJ). STUDY DESIGN: The subjects comprised 178 patients with internal derangement of the TMJ with closed lock. Treatment was provided using CPT in 102 cases and IGPT in 76 cases. Three variables, number of repunctures, maximal mouth opening distance, and pain threshold according to a visual analogue scale, were measured and compared between IGPT and CPT groups. RESULTS: Access to the superior joint cavity was achieved without correcting the puncture point in 97% of patients who underwent IGPT and 82% of patients in the CPT group. Significant differences were seen in 1-week maximal mouth opening and pain threshold between IGPT and CPT groups (P < .05 each) and resetting of the puncture point was significantly less frequent using IGPT compared with CPT (P < .05). CONCLUSIONS: IGPT is effective for pain mitigation and improves mouth opening during the early postoperative period after pumping manipulation treatment.