Evaluation of Prosthetic Complications with Metal-Acrylic Resin Implant-Fixed Complete Dentures: A Medium- and Long-Term Retrospective Analysis with Up to 13 Years of Follow-up

PURPOSE: To present prosthetic complications observed in the medium and long term in patients treated with metal-acrylic resin implant-supported fixed complete dentures (MAIFCDs). MATERIALS AND METHODS: A total of 87 patients who were treated with MAIFCDs were included. Acrylic resin (denture teeth and base) fracture, screw loosening (prosthetic or abutment), screw (prosthetic or abutment), and framework fracture were analyzed for descriptive statistics. Product-limit survival estimates were used for the cumulative no-complication rate (CNCR) of prostheses. All results were assessed using α = .05. RESULTS: The average observation time was 42.9 months (range: 19 to 153). Of 597 implants, 8 mandibular (44.4%) and 10 maxillary implants (55.6%) failed. In total, 29 patients (33.3%) experienced no complications in an average of 7 years, and 58 patients (66.6%) experienced at least one complication. The average time for the first complication to occur was 23 months (range: 1 to 97 months). The average number of complications was 5.9/patient. Acrylic resin complications were the most frequent, followed by screw loosening, screw fracture, and framework fracture. Of those patients with complications, 9 (16%) had maxillary MAIFCDs with an average of 4 complications. In total, 28 patients (48%) had only mandibular MAIFCDs with an average of 5 complications, and 21 patients (36%) had both arches treated with MAIFCDs with an average of 9 complications. Mandibular MAIFCDPs in women had a higher CNCR compared to maxillary MAIFCDs of both women and men and when both arches of women were treated with MAIFCDs (P < .05). CONCLUSIONS: The CNCR of MAIFCDs differed depending on the arch treated and sex. Mandibular MAIFCDs in women had a lower complication rate than MAIFCDs in other arch-sex pairs. Acrylic resin related complications were commonly observed as well as prosthetic screw loosening.

Illuminant effect on the coverage error of a gingiva-colored composite resin shade guide.

STATEMENT OF PROBLEM: Dental clinicians face challenges when selecting the proper gingiva-colored composite resin. PURPOSE: The purpose of this study was to evaluate the coverage error (CE) of a gingiva-colored dental composite resin shade guide with regard to the optical characteristics of the attached gingiva of a selected population under 2 different illuminants: Commission Internationale de l'Eclairage (CIE) illuminants A and D65. MATERIAL AND METHODS: The spectral reflectance (SR) values of 12 shade tabs of a gingiva-colored composite resin (Amaris gingiva) were measured at 3 different locations without a backing by using a spectroradiometer and an external light source at wavelengths of 380 to 780 nm at 2-nm intervals. All SR measurements were made using 0-degree observer and 45-degree illumination, with target size 1.1 mm in diameter. The attached gingiva (AG) of 120 participants was measured with the same protocol. CIELab values were calculated from the spectral reflectance values. CEs of the attached gingiva for each of the 120 participants for each of the shade tabs and the 2 illuminants and their combination were determined and averaged. The CIEDE2000 color differences were analyzed by a repeated measures ANOVA (using the maximum likelihood estimation method and the Satterthwaite degrees of freedom method) (α=.001). RESULTS: The CIEDE2000 color difference for each person's gingiva to the closest match in color to the shade guide was determined separately for CIE illuminants A and D65. CE was calculated as the averages of these color differences and was found to be 4.0 for CIE illuminant D65 and 5.8 for CIE illuminant A. CONCLUSIONS: The tested gingiva-colored shade guide had different CEs under illuminant D65 than under illuminant A and exhibited metamerism. ΔE for both illuminants was greater than the clinically acceptable range reported in the literature.

Effect of simulated mastication on the surface roughness of three ceramic systems.

STATEMENT OF PROBLEM: Zirconia complete coverage crowns are being widely used as restorations because of their high strength and improved esthetics. Data are sparse about the change in surface roughness of this ceramic material after repeated mastication cycles of opposing enamel. PURPOSE: The purpose of this study was to investigate changes in the surface roughness after being subjected to 3-body wear-opposing human enamel of 3 types of ceramics: dense sintered yttrium-stabilized zirconia (Z); lithium disilicate (L); and a conventional low-fusing feldspathic porcelain (P) treated to impart a rough, smooth, or glazed surface. MATERIAL AND METHODS: Twenty-four specimens of each of the Z and L ceramic were sectioned from computer-aided design and computer-aided manufacturing blocks into rectangular plates (15×12×2 mm). Twenty-four specimens of the feldspathic porcelain were formed into disks (12-mm diameter) from powders compressed in a silicone mold. All specimens (n=72) were prepared according to the manufacturers' recommendations. Specimens of each ceramic group were placed into 1 of 3 groups: group R, rough surface finish; group S, smooth surface finish; and group G, glazed surface finish. A total of 72 specimens (9 groups with 8 specimens each) was placed in a 3-body wear simulator, with standardized enamel specimens (n=72) acting as the substrate. The changes in surface roughness of the ceramic specimens were evaluated after 50,000 cycles. Data were analyzed by a repeated measures 3-way ANOVA mixed procedure with the Satterthwaite method for degrees of freedom and maximum likelihood estimation of the covariance parameters (α=.05). RESULTS: Data showed that the PS group exhibited the largest change in surface roughness, becoming significantly rougher (P<.004). The LR group became significantly smoother (P=.012). CONCLUSIONS: The surfaces of monolithic zirconia ceramic and lithium disilicate did not become as rough as the surface of conventional feldspathic porcelain after enamel wear.

Factors related to the willingness of Palestinian dentists to treat patients with blood-borne diseases.

This study aimed to explore, using groups of simulated patients, the willingness of Palestinian dentists to treat patients with blood-borne diseases. Simulated patients conducted a telephone survey of a random sample of dentists registered with the Palestinian Dental Association. A random system was used to assign dentists to one of two groups, in which simulated patients randomly identified themselves with either human immunodeficiency virus (HIV) or hepatitis B virus (HBV) and asked for a dental appointment. Three-hundred and four dentists (76%) responded to our telephone survey. Sixty-six per cent accepted requests for appointments and 34% declined the appointment requests. Sixty-eight per cent of the dentists declined appointment requests from patients with HIV and 32% declined appointments from patients with HBV. Dentist's gender, 'blood-borne disease type', 'place of private practice', 'country of graduation' and 'years since graduation' were all significant predictors in the final logistic model. More than one-third of our respondents declined appointment requests from patients with blood-borne disease, two-thirds of which were for patients who identified themselves as having HIV. Education and training programmes are needed to improve attitudes of dentists - especially female dentists, older dentists and dentists practising in northern governorates - towards patients with blood-borne diseases.

Three-body wear potential of dental yttrium-stabilized zirconia ceramic after grinding, polishing, and glazing treatments.

STATEMENT OF PROBLEM: Zirconia complete-coverage crowns are being widely used as restorations because of their improved esthetic characteristics. Data about the enamel wear potential of this ceramic after chair side adjustments are sparse. PURPOSE: The purpose of this study was to investigate the 3-body wear of enamel opposing 3 types of ceramic (dense sintered yttrium-stabilized zirconia; Crystal Zirconia; DLMS) (Z), a lithium disilicate (IPS e-max CAD; Ivoclar Vivadent) (E), and a conventional low-fusing feldspathic porcelain (VitaVMK-Master; Vita Zahnfabrik) (P), treated to impart a rough, smooth, or glazed surface. MATERIAL AND METHODS: Twenty-four specimens of each of the zirconia and the lithium disilicate ceramic were sectioned from computer-aided design and computer-aided manufacturing blocks into rectangular plates (15×12×2 mm). Twenty-four specimens of the feldspathic porcelain were formed into disks (12 mm diameter) from powders compressed in a silicone mold. All specimens (n=72) were prepared according to the manufacturers' recommendations. Specimens of each ceramic group were placed into 1 of 3 groups: group R, rough surface finish; group S, smooth surface finish; and group G, glazed surface finish. A total of 9 groups with 8 specimens each were placed in a 3-body wear simulator, with standardized enamel specimens (n=72) acting as the substrate. The wear of the enamel specimens was evaluated after 50,000 cycles. The data were analyzed with 2-way ANOVA and the Tukey HSD multiple comparison test (α=.05). RESULTS: The data showed that the smooth zirconia group (ZS) was associated with the least amount of enamel wear (1.26 ±0.55 mm(2)). The most antagonistic enamel wear was associated with the glazed groups ZG (5.58 ±0.66 mm(2)), EG (3.29 ±1.29 mm(2)), and PG (4.2 ±1.27 mm(2)). CONCLUSIONS: The degree of enamel wear associated with monolithic zirconia was similar to conventional feldspathic porcelain. Smoothly polished ceramic surfaces resulted in less wear of antagonistic enamel than glazing.

Development and evaluation of an interactive dental video game to teach dentin bonding.

Written and clinical tests compared the change in clinical knowledge and practical clinical skill of first-year dental students watching a clinical video recording of the three-step etch-and-rinse resin bonding system to those using an interactive dental video game teaching the same procedure. The research design was a randomized controlled trial with eighty first-year dental students enrolled in the preclinical operative dentistry course. Students' change in knowledge was measured through written examination using a pre-test and a post-test, as well as clinical tests in the form of a benchtop shear bond strength test. There was no statistically significant difference between teaching methods in regards to change in either knowledge or clinical skills, with one minor exception relating to the wetness of dentin following etching. Students expressed their preference for an interactive self-paced method of teaching.