The effect of various occlusal reduction levels on postoperative pain in teeth with symptomatic apical periodontitis using computerized analysis: a prospective, randomized, double-blind study.

OBJECTIVE: The objective of this study was to evaluate the effect of various occlusal reduction levels on the postoperative pain in teeth diagnosed as symptomatic apical periodontitis by using a computerized analysis system. MATERIALS AND METHODS: Thirty-nine molar teeth with symptomatic apical periodontitis were included. After the root canal preparation and filling was performed, the subjects were divided into three groups according to the level of occlusal reduction determined by using T-Scan (T-Scan III for Windows, Tekscan Inc., South Boston, MA) as follows: (1) no reduction (control), (2) semi-reduction, and (3) full-reduction groups. Preoperative and postoperative pain levels using visual analogue scale, percussion pain, and analgesic intake were recorded for each subject. The data were evaluated statistically using two-way analysis of variance and Holm-Sidak post hoc tests at a 95 % confidence level (P = 0.05). RESULTS: There was no significant difference between the groups in terms of occlusal reduction (P > 0.005). CONCLUSION: Within the limitation of the present study, there were no significant differences among the no reduction, semi-reduction, and full-reduction groups at 1, 3, 5, and 7 days in terms of postoperative pain levels. CLINICAL RELEVANCE: Occlusal reduction, determined using a computerized analysis system, did not influence the postoperative pain in teeth diagnosed as symptomatic apical periodontitis.

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.

Effects of tongue movements on lingual sulcus depth while border molding in mandibular complete dentures.

BACKGROUND: In general, people speak and swallow frequently in their daily lives rather than making exaggerated tongue movements. AIM: The aim was to compare the effect of tongue movements on lingual sulcus depth, during the border molding process of impression making of mandibular complete dentures. SETTINGS AND DESIGN: In total, 32 double master impressions were made. One of these pairs was obtained by allowing the patient to swallow and the other by enabling the tongue to make excessive movements. MATERIALS AND METHODS: Measurements were taken from different regions of the lingual sulcus by determining the length of the parallel lines drawn from fixed points marked on the residual ridge crest to the deepest point of the alveolingual sulcus. These measurements were performed using a RMI three-dimensional measurement system. STATISTICAL ANALYSIS USED: Data were compared using the paired t-test (alpha = 0.05). RESULTS AND CONCLUSION: The high value found in casts with border molding, while swallowing was statistically significant in vertical and horizontal directions of the anterior lingual sulcus region (<0.001), vertical direction of the middle lingual sulcus region (MLSR) (<0.05) and horizontal direction of the retromylohyoid and MLSR (<0.05). According to the paired t-test, the mean differences between the 32 casts were statistically significant (<0.001). Within the limitations of this study, the swallowing in the vertical and horizontal directions provided higher values compared to the excessive movement of the tongue.

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.

Effects of post surface treatments including Er:YAG laser with different parameters on the pull-out bond strength of the fiber posts.

This study aims to evaluate the effects of Er:YAG laser irradiation under different power settings on the pull-out bond strengths of fiber-reinforced composite posts. The crowns of single-rooted 60 teeth were removed by separation and the root canals were cleaned and shaped. Root canals were filled and post spaces were prepared. Sixty fiber posts were divided into five groups according to surface treatment methods as follows: an untreated control group, a sandblasting-coated group, and three groups undergoing surface preparation with Er:YAG laser under three different power settings (150, 300, and 450 mJ at 10 Hz for 60 s at 100-µs pulse duration). After root canal procedures, fiber posts were cemented to the root canal. After all of the specimens were set, pull-out tests were performed using a universal testing machine at a crosshead speed of 2 mm/min. The data were analyzed using one-way ANOVA and Tukey post-hoc test (p < 0.05). The pull-out strength values ranged between 5.26 and 6.76 Mpa. The lowest values were observed in the groups without surface treatment. Surface treatment applied by 4.5-W Er:YAG laser increased the pull-out bond strength compared to the control group (p < 0.05). 4.5-W Er:YAG laser irradiation increased the pull-out bond strength of fiber posts to resin cement.

Porcelain thickness and cement shade effects on the colour and translucency of porcelain veneering materials.

OBJECTIVE: Purposes of this in vitro study include evaluating colour changes in combinations of feldspathic porcelain and cement resulting from different thicknesses of porcelain and different shades of composite luting agent, and evaluating relative translucency parameter (RTP) values. MATERIALS AND METHODS: Porcelain discs of shade A1 at nominal thicknesses of 0.5 and 1.0mm were bonded to cements of three shades in a factorial design. Colours were calculated for CIE D65 Illuminant and Standard Human Observer on black, grey and white backings. A colour difference (CD) was calculated of each possible pair of different porcelain thickness values for the same cement shade and each possible pair of different cement shades for the same porcelain thickness. RTP was analyzed by ANOVA and selected pairwise comparisons. RESULTS: All mean CDs studied were perceptible and most were at or greater than the clinical acceptability threshold, with the notable exception that the mean CDs and their confidence limits were below the clinical acceptability threshold for a change in porcelain thickness when utilizing the Clear cement shade. Variation in the shade of the resin luting cement will result in CDs which are near or beyond clinical acceptability. A decrease in porcelain thickness did significantly increase RTP when bonded to the resin cement shades studied. CONCLUSION: Changes in porcelain thickness or cement shade may adversely affect basic aesthetic properties of these materials. Development of methods for analyzing aesthetic effects over greater ranges of thickness for these materials would improve the prognosis for using these materials.

The effect of staining solutions on the color stability of provisional prosthodontic materials.

OBJECTIVES: The aim of this study was to evaluate the effects of staining solutions on the color stability of self-cure provisional resin materials. METHODS: The specimens were prepared for each of three auto-polymerized bis-acryl resin and auto-polymerized methyl methacrylate provisional resin material. The baseline color values were measured with a colorimeter according to the CIE L(*)a(*)b(*) color scale. After the first measurement (T(0)), specimens were placed in staining solutions (coffee, coca-cola, burn and distilled water for control group) and the other measurements were taken after 24h (T(1)), 1 week (T(2)) and 4 weeks (T(3)). RESULTS: Data were analyze statistically by (a) repeated measures (ANOVA), (b) one and two way ANOVA, and (c) Tukey HSD multiple comparison tests. At the 24h immersion period, the post hoc analysis indicated that AccessCrown-coffee revealed the highest ΔE(*) values (4.4). At the second immersion period (1 week), Structur2 SC-coffee had the highest ΔE(*) values compared with other materials (5.4). CONCLUSIONS: The degrees of discoloration were increased with immersion time. The methylmethacrylate resin was more resistant to discoloration than bis-acryl resins. After immersion for 30 days, the coffee solution resulted in unacceptable discoloration for all the tested materials.

Management of fractured permanent incisors: 1 year follow-up.

UNLABELLED: This clinical report describes the treatment of a left maxillary permanent incisor that had a complicated crown-root fracture with multiple fragments and a right maxillary permanent incisor which had an uncomplicated crown fracture. The 17-year-old female patient was presented to Ataturk University's Dentistry Faculty with posttraumatic injuries. The treatment plan included fracture segment reattachment, composite laminate veneer of the left maxillary incisor and composite restoration of the right maxillary incisor. The restorations were successful after 1-year follow-up according to the modified USPHS criteria. CLINICAL SIGNIFICANCE: The treatment of anterior region's traumas in a single appointment would provide patient's expectation as well as preventive of remaining dental hard tissues.