Effects of cementation technique and cement thickness on the retention and amount of excess cement in implant-supported restorations.

Purpose: To assess the amount of excess cement and the retentive strengths of two different cementation techniques (conventional cementation and practice abutment) using copings fabricated with three different cement thicknesses (20 µm, 35 µm, and 50 µm). Materials and methods: Thirty zirconia copings were fabricated on screw retained abutments and randomly divided into three equal groups (n = 10) according to the cement thickness (20 µm, 35 µm, and 50 µm). Each group was cemented with tow cementation techniques. Cementation was performed with provisional cement (Temp-Bond). In the conventional cementation technique, cement was applied until each coping was approximately half filled, and the copings were subsequently placed on the implant-abutment assembly. Then, the copings were cleaned and cemented using the practice abutment cementation technique to remove excess cement prior to the process. Each technique was performed using copings with three different cement thicknesses (20 µm, 35 µm, and 50 µm). The specimens with the cemented copings were weighed on a high-precision analytical balance before and after removing the extruded cement, and the differences between the two measurements were calculated. Then, each specimen was subjected to a pullout test using a universal testing machine. The load required to dislodge the coping was recorded. The data were analyzed using two-way and one-way analysis of variance and independent sample t tests at a significance level of 0.05. Results: The highest retention values were obtained for 20 µm cement thickness in the conventional technique and the practice abutment cementation technique. The amount of excess cement was the highest for the 50 µm cement thickness obtained for both cementation techniques, whereas the lowest mean values were recorded for the 20 µm cement thickness. Conclusion: The conventional cementation technique is recommended over the practice abutment technique to increase the retention of crowns cemented with provisional cement. However, care must be taken to remove the extruded cement. A cement thickness of 20 µm is preferable for enhancing the retention of cemented crowns and for reducing the amount of excess cement when applying both conventional and practical abutment cementation approaches.

Positive surgical margins after breast-conserving surgery for ductal carcinoma in-situ: does histologic grade or estrogen receptor status matter?

PURPOSE: DCIS has been shown to have a higher rate of positive margins following breast-conserving surgery (BCS) than invasive breast cancer. We aim to analyze certain factors of DCIS, specifically histologic grade and estrogen receptor (ER) status, in patients with positive surgical margins following BCS to determine if there is an association. METHODS: A retrospective review of our institutional patient registry was performed to identify women with DCIS and microinvasive DCIS who underwent BCS by a single surgeon from 1999 to 2021. Demographics and clinicopathologic characteristics between patients with and without positive surgical margins were compared using chi-square or Student's t-test. We assessed factors associated with positive margins using univariate and multivariable logistic regression. RESULTS: Of the 615 patients evaluated, there was no significant difference in demographics between the patients with and without positive surgical margins. Increasing tumor size was an independent risk factor for margin positivity (P = < 0.001). On univariate analysis both high histologic grade (P = 0.009) and negative ER status (P = < 0.001) were significantly associated with positive surgical margins. However, when adjusted in multivariable analysis, only negative ER status remained significantly associated with margin positivity (OR = 0.39 [95% CI 0.20-0.77]; P = 0.006). CONCLUSION: The study confirms increased tumor size as a risk factor for positive surgical margins. We also demonstrated that ER negative DCIS was independently associated with a higher rate of positive margins after BCS. Given this information, we can modify our surgical approach to reduce rate of positive margins in patients with large-sized ER negative DCIS.

Use of indocyanine green for sentinel lymph node biopsy in melanoma.

Sentinel lymph node (SLN) biopsy for cutaneous melanoma is a critical part of designing therapy for the skin malignancy. A retrospective review of 54 patients with cutaneous melanoma who underwent SLN biopsy guided by both radiotracer injection and indocyanine green (ICG) fluorescent dye compared the accuracy of identifying the SLN using each method. Patients were injected preoperatively with radiotracer at the site of the primary melanoma and intraoperatively with 2.5 mg of ICG. The detection of the SLN was compared between the two methods. Patients were followed to determine local recurrence and survival from 5 months to 4 years. ICG and radiotracer identified the SLN in 52 of 54 patients. In those patients who mapped, 52 of 52 showed mapping to the same node or nodes. The rate of cancer involvement in the identified node was 19.2% for both techniques. There was no difference in recurrence or survival between the two methods of SLN identification in short follow-up. In conclusion, ICG injection and mapping to identify SLN in cutaneous melanoma is confirmatory for radiotracer mapping and in the future may be an accurate and less costly method for SLN biopsy in cutaneous melanoma.

A Comparative Evaluation of the Antimicrobial Effects of Different Mouthrinses against Oral Pathogens: An In Vitro Study1.

AIM: To assess the antimicrobial effects of natural and semi-natural mouthrinses on isolates of Streptococcus mutans, Lactobacillus fermentum, and Lactobacillus casei obtained from the saliva samples and their reference strains. MATERIALS AND METHODS: Natural and semi-natural mouthrinses included in this study were herbal mix mouthrinse, cranberry mouthrinse, chlorhexidine digluconate mouthrinse, cranberry extract mixed with chlorhexidine digluconate mouthrinse, chlorhexidine digluconate mouthrinse with alcohol (positive control), and distilled water (negative control). The microbiological examination tests were minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and zone of inhibition test for the saliva isolates of S. mutans, L. fermentum, and L. casei while zone of inhibition test only for their reference strains. RESULT: Compared with distilled water, herbal mix, cranberry, cranberry mixed with chlorhexidine, chlorhexidine with alcohol (+), and chlorhexidine mouthrinses were associated with a significant increase of the zone of inhibition 34.354, 34.255, 34.219, 10.801, and 9.386, respectively. Both MIC and MBC were significantly higher in the cranberry mixed with chlorhexidine than in chlorhexidine with alcohol. The MIC and MBC of mouthrinses were significantly lower in the S. mutans and L. fermentum than in L. casei. CONCLUSION: Herbal mix and cranberry mouthrinses could be effective natural alternative to chlorhexidine mouthrinse with or without alcohol in improving oral health. CLINICAL SIGNIFICANCE: Different mouthrinses proposed in this study showed antimicrobial effects against the tested oral pathogens, and possibly the tested mouthrinses will lead for future formulation of natural or semi-natural pharmaceutical mouthrinses.

Fracture Resistance of Endodontically Treated Teeth Restored with Fiber Posts Luted with Composite Core Materials.

AIM: This study aimed to investigate the influence of using dual-cure composite core materials for fiber post luting on the fracture resistance of endodontically treated maxillary central incisors. MATERIALS AND METHODS: Fifty sound and recently extracted maxillary central incisors were endodontically treated and distributed into five groups. In the control group, access cavities were restored with the composite resin. Experimental groups had the coronal structure trimmed 2 mm above the cementoenamel junction. Teeth were restored with fiber posts and different combinations of luting and core materials: RelyX Unicem for post luting and MultiCore for core buildup; MultiCore for post luting and core buildup; RelyX Unicem for post luting and LuxaCore for core buildup; or LuxaCore for post luting and core buildup. All teeth were restored with zirconium crowns and subjected to thermocycling (6000 cycles 5/55°C). Loading of the teeth was applied at 135° to the palatal surface, using a universal testing machine at a cross-speed of 0.5 mm/minute until failure. The mode of failure was analyzed under a digital microscope. RESULTS: The fracture resistance of the control group was significantly higher than the experimental groups (p < 0.05). There was no significant difference between the experimental groups (p > 0.05). All teeth demonstrated nonrestorable failures. CONCLUSION: With the presence of the ferrule effect and crown restoration, the selected materials for post luting and core buildup have no significant influence on the fracture resistance of the endodontically treated teeth. CLINICAL SIGNIFICANCE: The use of the same dual-cure composite core materials for fiber post luting and core buildup would simplify the clinical procedure without enhancement of the fracture resistance of the endodontically treated tooth.

An in vitro evaluation of the effect of polishing on the stainability of different CAD/CAM ceramic materials.

PURPOSE: To determine the effect of coffee on the stainability of CAD/CAM ceramics after different surface treatment protocols. METHODS: Ninety specimens (2 mm × 10 mm) of CAD/CAM ceramic materials (Vitablocs Mark II, VITA Enamic, and VITA Suprinity) were prepared. The specimens were subdivided (n = 10) into three groups: G1: Glazed (control group), G2: Subjected to finishing and polishing, and G3: Re-glazed after finishing and polishing. The surface treatment was performed using a diamond polishing system for porcelain (Diapol) followed by applying a diamond polishing paste (Diapolisher). The specimens were immersed in distilled water for 24 h, and the baseline color measurement after finishing and polishing was recorded. Each group was then immersed in a staining solution (coffee) for one week, and the second color measurement was recorded. RESULTS: The color of the CAD/CAM ceramic materials in the finishing and polishing groups changed significantly after staining (P < 0.05). Statistically significant differences were noticed after staining in the polished groups of Vita Enamic and Vita Suprinity compared with the glazed group (control). However, the color change between the re-glazed and control groups was insignificant for all the materials (P > 0.05). Although the color change values of the three CAD/CAM materials increased, these changes were within the clinically acceptable value (ΔE < 3.3). CONCLUSION: Staining of the tested CAD/CAM ceramic materials increased the color change values within the clinically acceptable range in all the groups, with the highest values found after finishing and polishing. Re-glazing is recommended after surface adjustment for all the tested materials to increase their resistance to staining.

Comparative Evaluation of the Antimicrobial Effects of Different Mouthrinses against Streptococcus Mutans: An in Vitro Study.

Purpose: To assess the antimicrobial effects of different natural and semi-natural mouthrinses on isolates of S. mutans obtained from the saliva of Saudi children and reference strains of S mutans (ATCC 25175). Study design: Saliva samples were collected from 20 children. Natural and semi-natural mouthrinses included were herbal mix mouthrinse, cranberry mouthrinse, chlorhexidine digluconate mouthrinse, cranberry extract mixed with chlorhexidine digluconate mouthrinse, chlorhexidine digluconate mouthrinse with alcohol (positive control), and distilled water (negative control). The microbiological examination tests were minimal inhibitory concentration, minimal bactericidal concentration, and zone of inhibition for the saliva isolates of S. mutans while zone of inhibition test only for reference strain of S. mutans. Results: For reference strain in a comparison with the distilled water, the herbal mix, cranberry, cranberry mixed with chlorhexidine, chlorhexidine, and chlorhexidine with alcohol showed significantly increased zones of inhibition by 36.38, 36.25, 26.13, 17.75, and 12.38, respectively. For saliva isolates in a comparison with the distilled water, the herbal mix, cranberry, cranberry mixed with chlorhexidine, chlorhexidine, and chlorhexidine with alcohol showed significantly increased zones of inhibition by 38.00, 34.25, 22.94, 16.50, and 16.44, respectively. Chlorhexidine with alcohol showed significantly lower minimum inhibitory and bactericidal concentration than the other groups. Conclusions: Herbal mix and cranberry mouthrinses could be effective natural alternative to chlorhexidine mouthrinse with or without alcohol in affecting tested parameters.

Effect of Single Off-Axis Implant Placement on Abutment Screw Stability Under Lateral Loading.

PURPOSE: The aim of this study was to evaluate the effect of off-axis implant placement in relation to the prosthetic crown on abutment screw loosening under different directions of twisting moments. MATERIALS AND METHODS: Twenty-one implant assemblies were divided equally into three groups (n = 7). Each assembly consisted of an internal-octagon implant measuring 4.1 × 12 mm (standard plus implants) with corresponding 5.5-mm synocta abutments (Straumann) mounted in an epoxy resin-glass fiber composite. Group A had a straight implant configuration in relation to the prosthetic crown and was subjected to clockwise twisting moment (control). The other two groups, B and C, with off-axis implant placement were subjected to clockwise and counterclockwise moments, respectively. A lateral load of 80 N was applied to the specimens for 1 × 10(6) cycles at 90 degrees to the long axis of the implant. The loading point was 4 mm from the center of the implant in group A and 6 mm in groups B and C. The reverse torque value (RTV) of the abutment screw was measured before and after loading. Data were analyzed using a paired samples t test and one-way analysis of variance (ANOVA) at a significance level of α = .05. RESULTS: An increase in postloading RTV was found relative to preloading RTV in all groups, but was only significant in group A (P < .05). The mean reverse torque difference (RTD) was higher in group A (3.17 ± 1.04 Ncm), followed by groups B (1.03 ± 1.41 Ncm) and C (0.43 ± 1.09 Ncm). A significant difference in RTD was noted between group A and the remaining groups (P < .05). However, no significant difference was found between groups B and C (P > .05). CONCLUSION: Placement of an implant in an off-axis relation to the prosthetic crown resulted in significantly lower reverse torque values compared with straight implant configuration. However, the extent of reduction in Ncm is small and is considered clinically insignificant in the studied implant system. Furthermore, no significant difference was found in RTV between clockwise and counterclockwise twisting moments.