Association between initial complexity, frequency of refinements, treatment duration, and outcome in Invisalign orthodontic treatment.

INTRODUCTION: This study explored possible associations between treatment duration, initial complexity, outcomes in Invisalign therapy, and the number of refinements. METHODS: Three-dimensional models (initial, final, and refinements) of 355 Invisalign patients (114 males and 241 females; 33.8 ± 17.1 years) were analyzed using the Peer Assessment Rating (PAR) index questionnaire tool in the Ortho Analyzer software (version 2.0; 3Shape, Copenhagen, Denmark) to calculate the weighted total and individual PAR index scores for each component of the PAR index. Data related to demographics, treatment duration, and the number of refinements were collected. RESULTS: Treatment duration increased as the number of refinements increased. Percent of improvement was higher in PAR ≥22 group than PAR <22 with an increase in the number of refinements: 83.3% vs 73.8% for 2 refinements; 94.7% vs 91.2% for 3 refinements; and 100% vs 85.7% for ≥4 refinements. Those who achieved great improvement or improvement and those who did not were significantly different in treatment duration (P <0.001 and P = 0.027), number of refinements (≥3 refinements; P <0.001), initial occlusal severity (PAR ≥22; P <0.01 and P = 0.031). Most subjects achieved improvement after the first refinement (64.5% for PAR <22 and 78.5% for PAR ≥22). Few had ≥4 refinements, and if they did, none achieved improvement with additional refinements. CONCLUSIONS: Initial complexity for an Invisalign case is associated with treatment duration, achieved outcomes, and the number of refinements. Treatment duration increased with an increased number of refinements. Great improvement or improvement for the first time dropped to 0 if additional refinements were carried out after 3. Therefore, performing additional refinements does not necessarily mean better occlusal outcomes.

Osteonecrosis of the Jaw Developed in Mice: DISEASE VARIANTS REGULATED BY γδ T CELLS IN ORAL MUCOSAL BARRIER IMMUNITY.

Osteonecrosis of the jaw (ONJ), an uncommon co-morbidity in patients treated with bisphosphonates (BP), occurs in the segment of jawbone interfacing oral mucosa. This study aimed to investigate a role of oral mucosal barrier γδ T cells in the pathogenesis of ONJ. Female C57Bl/6J (B6) mice received a bolus zoledronate intravenous injection (ZOL, 540 µg/kg), and their maxillary left first molars were extracted 1 week later. ZOL-treated mice (WT ZOL) delayed oral wound healing with patent open wounds 4 weeks after tooth extraction with characteristic oral epithelial hyperplasia. γδ T cells appeared within the tooth extraction site and hyperplastic epithelium in WT ZOL mice. In ZOL-treated γδ T cell null (Tcrd(-/-) ZOL) mice, the tooth extraction open wound progressively closed; however, histological ONJ-like lesions were identified in 75 and 60% of WT ZOL and Tcrd(-/-) ZOL mice, respectively. Although the bone exposure phenotype of ONJ was predominantly observed in WT ZOL mice, Tcrd(-/-) ZOL mice developed the pustule/fistula disease phenotype. We further addressed the role of γδ T cells from human peripheral blood (h-γδ T cells). When co-cultured with ZOL-pretreated human osteoclasts in vitro, h-γδ T cells exhibited rapid expansion and robust IFN-γ secretion. When h-γδ T cells were injected into ZOL-treated immunodeficient (Rag2(-/-) ZOL) mice, the oral epithelial hyperplasia developed. However, Rag2(-/-) ZOL mice did not develop osteonecrosis. The results indicate that γδ T cells are unlikely to influence the core osteonecrosis mechanism; however, they may serve as a critical modifier contributing to the different oral mucosal disease variations of ONJ.