The aim of the study was to determine the prevalence of white-spot lesions (WSLs) in patients with fixed orthodontic appliances. The cross-sectional study sample consisted of three groups of patients: group I, 59 patients treated orthodontically for 6 months; group II, 64 patients treated for 12 months; group 0 (control), 68 patients examined immediately before appliance placement. All groups were treated with a 0.022-inch slot preadjusted appliance and they wore a functional fixed appliance. The presence of WSLs was evaluated by visual examination using the scoring system proposed by Gorelick. The groups were evaluated for differences in the prevalence of at least one WSL using Fisher’s exact test, followed by Bonferroni pairwise comparisons. The prevalence of WSLs by tooth type was evaluated with logistic regression (P < 0.05). Intraobserver agreement was assessed by means of the Cohen ĸ statistical method. There were no significant differences in the prevalence of WSLs between patients treated for 6 and 12 months (P = 0.855); however, there were significantly more WSLs in groups I and II than in group 0 (P = 0.000). No significant differences were found between girls and boys (P = 1.000). The mandibular first molars and maxillary lateral incisors were the most affected teeth, in both the treated and untreated groups. The study revealed significant decalcification at 6 months after orthodontic bonding. Considering how quickly these lesions can develop and become irreversible, early diagnosis is of critical importance.

To compare the fracture resistance and mode of failure of CAD-CAM monolithic zirconia crowns with different occlusal thickness. Forty CAD-CAM monolithic zirconia crowns with different occlusal thickness were randomly distributed into 4 experimental groups: 2.0mm (group 1), 1.5mm (group 2), 1.0mm (group 3) and 0.5mm (group 4). The restorations were cemented onto human molars with a self-adhesive resin cement. The specimens were loaded until fracture; the fracture resistance and mode of failure were recorded. The data were statistically analyzed with the one-way ANOVA followed by the Fisher׳s Exact test with Bonferroni׳s correction (p=0.05). The fracture resistance values of all the specimens exceeded the maximum physiological occlusal loads in molar regions. All the crowns showed cohesive microcracks of the zirconia core; only 1 crown with a thickness of 0.5mm was interested by a complete fracture. The occlusal thickness of CAD-CAM monolithic zirconia crowns did not influence either the fracture resistance and the mode of failure of the restorations; the occlusal thickness of CAD-CAM monolithic zirconia crowns can be reduced up to a lower bound of 0.5mm keeping a sufficient strength to withstand occlusal loads; CAD-CAM monolithic zirconia crowns showed sufficient fracture resistance to be used in molar regions, even in a thin configuration (0.5mm).

Enrico Gherlone, MD, DMD, PhD/Paolo Capparé, MD, MS/Raffale Vinci, MD, DMD, MS/Francesco Ferrini, DDS/Giorgio Gastaldi, MD, DMD/Roberto Crespi, MD, MS: Purpose: This study aimed to evaluate the most accurate impression technique for ?All on Four? restoration, comparing conventional (CIG) and digital impressions (DIG). Materials and Methods: Patients randomly selected for this study were required to be edentulous in at least one arch, presenting with severe posterior mandibular or maxillary atrophy. All patients underwent full-arch immediate-load rehabilitations, which were fixed to a total of four implants (two axial and two tilted). Following implant placement, patients were stratified into two groups. Conventional pick-up was carried out in the control group, and digital impressions were performed in the test group. Following prosthetic rehabilitation, patients underwent intraoral digital radiographs to check for the presence of voids at the bar?implant connection and to evaluate accuracy. Three-, 6-, and 12-month follow-up examinations were performed. Results: A total of 25 patients received immediately loaded ?All-on-Four? prostheses (17 maxillary, 13 mandibular) supported by four implants (total 120 implants), of which five received both maxillary and mandibular prosthetic rehabilitation (three patients in CIG, two patients in DIG). No implant dropouts occurred, showing a survival rate of 100%. The digital impression procedure required significantly less time than the conventional procedure (P < .001). Conclusion: Results demonstrate that it is possible to develop computer-aided design/computer-assisted manufacturing (CAD/CAM) cobalt-chromium full-arch rehabilitations with satisfactory accuracy using digital impression techniques.