Assessment of the reproducibility and precision of milling and 3D printing surgical guides.

BACKGROUND: Technology advancement has rising in the past decade and brought several innovations and improvements. In dentistry, this advances provided more comfortable and quick procedures to both the patient and the dental surgeon, generating less predictability in the final result. Several techniques has been developed for the preparation of surgical guides aiming at the optimization of surgical procedures. The present study aimed to evaluate the reproducibility and precision of two types of surgical guides obtained using 3D printing and milling methods. METHODS: A virtual model was developed that allowed the virtual design of milled (n = 10) or 3D printed (n = 10) surgical guides. The surgical guides were digitally oriented and overlapped on the virtual model. For the milling guides, the Sirona Dentsply system was used, while the 3D printing guides were produced using EnvisionTEC's Perfactory P4K Life Series 3D printer and E-Guide Tint, a biocompatible Class I certified material. The precision and trueness of each group during overlap were assessed. The data were analyzed with GraphPad software using the Kolmogorov-Smirnov test for normality and Student's t test for the variables. RESULTS: The Kolmogorov-Smirnov test showed a normal distribution of the data. Comparisons between groups showed no statistically significant differences for trueness (p = 0.529) or precision (p = 0.3021). However, a significant difference was observed in the standard deviation of mismatches regarding accuracy from the master model (p < 0.0001). CONCLUSIONS: Within the limits of this study, surgical guides fabricated by milling or prototyped processes achieved similar results.

In Vitro Assessment of the Abrasion Resistance of Two Types of Artificial Teeth Submitted to Brushing.

PURPOSE: To assess the effect of brushing with different solutions on the abrasion resistance of two types of acrylic resin teeth. MATERIALS AND METHODS: Maxillary premolars from two types of acrylic teeth (Biotone and Biotone IPN) were divided into six groups (n = 12), according to the solution used during brushing: distilled water (control), coconut soap, or dentifrice. A mechanical brushing machine was used to simulate approximately 1 year of brushing (11,000 strokes). The weight loss (WL) of teeth was obtained from the difference between the initial (IW) and final weight (FW) of each specimen, and the mean of percentage of weight loss (PWL) was calculated for each group. Data were analyzed using the Kruskal-Wallis test, followed by Bonferroni's post-test comparison (α = 0.05). RESULTS: A statistically significant difference was found for the factor solution (p < 0.001). Brushing using dentifrice caused the highest values of weight loss (-0.50%), in comparison with the groups brushed with coconut soap (0.00%) or distilled water (0.00%). CONCLUSIONS: For both types of artificial teeth, brushing with dentifrice produced higher abrasion than brushing with coconut soap or water.

Osseointegration assessment of chairside argon-based nonthermal plasma-treated Ca-P coated dental implants.

This study investigated the effect of an Argon-based nonthermal plasma (NTP) surface treatment-operated chairside at atmospheric pressure conditions applied immediately prior to dental implant placement in a canine model. Surfaces investigated comprised: Calcium-Phosphate (CaP) and CaP + NTP (CaP-Plasma). Surface energy was characterized by the Owens-Wendt-Rabel-Kaelble method and chemistry by X-ray photoelectron spectroscopy (XPS). Six adult beagles dogs received 2 plateau-root form implants (n = 1 each surface) in each radii, providing implants that remained 1 and 3 weeks in vivo. Histometric parameters assessed were bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Statistical analysis was performed by Kruskall-Wallis (95% level of significance) and Dunn's post-hoc test. The XPS analysis showed peaks of Ca, C, O, and P for the CaP and CaP-Plasma surfaces. Both surfaces presented carbon primarily as hydrocarbon (C-C, C-H) with lower levels of oxidized carbon forms. The CaP surface presented atomic percent values of 38, 42, 11, and 7 for C, O, Ca, and P, respectively, and the CaP-Plasma presented increases in O, Ca, and P atomic percent levels at 53, 12, and 13, respectively, in addition to a decrease in C content at 18 atomic percent. At 1 week no difference was found in histometric parameters between groups. At 3 weeks significantly higher BIC and BAFO were observed for CaP-Plasma treated surfaces. Surface elemental chemistry was modified by the Ar-based NTP. Ar-based NTP improved bone formation around plateau-root form implants at 3 weeks compared with CaP treatment alone.

Radiographic assessment of bone density around integrated titanium implants after ovariectomy in rats.

OBJECTIVES: This study evaluated the influence of ovariectomy 8 weeks after implant placement on bone integrated to titanium implants. MATERIAL AND METHODS: Thirty-eight female rats were submitted to a titanium implant at the tibiae proximal methaphysis. After a healing period of 8 weeks the animals were randomly divided into three groups: control (CTL-10 animals), sham-operated (SHAM-14 animals) and ovariectomy (OVX-14 animals). The CTL group was then sacrificed in order to confirm integration of the implant. The SHAM group was submitted to fictitious surgery and the OVX group was submitted to bilateral ovariectomy. After 12 weeks post-implant placement, the SHAM and OVX groups were sacrificed. In order to confirm the systemic osteopenia in rats, a dual-energy X-ray absorptiometry (DXA) was performed. For the evaluation of bone density, digital radiographs were taken. The grey level of the bone adjacent to implant was measured using image software and the bone density was calculated at six points on both sides of the implant. RESULTS: Densitometry measurements of the femur confirmed systemic bone mass loss in the OVX group. Individualized bone analyses of different regions surrounding the implant showed a significantly lower radiographic bone density (P < 0.05) in the cancellous region of the OVX group (77.48 +/- 23.39 grey levels) when compared with the CTL and SHAM groups (91.61 +/- 32.10 and 102.57 +/- 32.50 grey levels, respectively). CONCLUSIONS: The present study showed a decrease of the radiographic bone density in the cancellous region of bone around titanium implants placed 8 weeks before ovariectomy in rats.