Effect of double conical abutment screw on implant preload.

OBJECTIVE: This study compared the loosening torque of experimental double conical abutment screws to that of conventional conical abutment screws and flat-head screws in implants with internal connections before and after mechanical loading. MATERIAL AND METHODS: Eighty implant-screw-abutment assemblies were divided into four groups: flat-head screw (Xive S), conical screw (Straumann), conical screw (Nobel Biocare), and double conical screw (RTB). Abutments were tightened to a torque of 30 Ncm. After 10 min, they were retightened and loosening torque was measured. The same abutments were then retightened with new screws to a torque of 30 Ncm and, again, retightened after 10 min. They were then mechanically loaded for 3 000 000 cycles, and loosening torque was again measured. Data were collected, and an exploratory analysis was performed. RESULTS: Comparisons before mechanical cycling showed significant differences between groups. After mechanical cycling, only the comparisons of Straumann and Nobel Biocare showed no significant differences. Considering the same group before and after mechanical cycling, all comparisons showed significant differences. CONCLUSION: The shape of the abutment screw head significantly influenced loosening torque: Double conical-head screws showed significantly higher loosening torque values than conical-head screws. Conical-head screws showed higher loosening torque values than conventional flat-head screws before and after loading.

Influence of different conditioning methods on immediate and delayed dentin sealing.

STATEMENT OF PROBLEM: Data are needed to evaluate the effect of various conditioning methods on immediate and delayed dentin sealing. PURPOSE: The purpose of this study was to test bond strength and surface configuration of immediate and delayed dentin sealing surfaces after applying different surface conditioning methods. MATERIAL AND METHODS: A total of 96 premolars were allocated to the immediate and delayed groups. The groups differed in the timing of dentin sealing. The immediate-group specimens were sealed with a self-etching adhesive immediately after preparation. The delayed-group specimens were sealed before the final ceramic restoration bonding. Provisional restorations were cemented on immediate-group and delayed-group specimens for 1 week. Four conditioning methods were used: polishing with fluoride-free pumice paste, airborne-particle abrasion with silicoated aluminum oxide, glycin, or calcium carbonate. After 24-hour storage, the shear bond strength was tested. The fractured specimens were optically inspected with a stereomicroscope. An optical 3-dimensional surface analysis was performed for quantitative and qualitative evaluation. A 2-way ANOVA with post hoc Tukey honestly significant difference tests for significant effects was performed to investigate effects of the 2 factors, sealing and conditioning, and their interaction (α=.05). RESULTS: Two-way ANOVA found significant differences between the sealing and conditioning groups. The immediate group had significantly lower bond strengths than the delayed group. In all groups, surface polishing produced the highest bond strengths, and airborne-particle abrasion with calcium carbonate produced the lowest. Fracture analysis found more failures in the adhesive layers in the immediate groups and a prevalence of mixed failures in the delayed groups. The surface analysis found significant abrasion and roughness when airborne-particle abrasion with silicoated aluminum oxide was used for immediate and delayed dentin sealing surfaces. CONCLUSIONS: Polishing and airborne-particle abrasion with silicoated aluminum oxide or glycin are efficient methods in conditioning immediate and delayed dentin sealing surfaces. Airborne-particle abrasion with silicoated aluminum oxide leaves significant surface alterations on both types of surfaces.

Color stability of different composite resin materials.

STATEMENT OF PROBLEM: Data are needed to better predict the color stability of current composite resin materials. PURPOSE: The purpose of this study was to evaluate the impact of different storage solutions on the color stability of different composite resin materials. MATERIAL AND METHODS: Different restorative and adhesive composite resin specimens (dual-polymerizing self-adhesive resin cement, autopolymerizing resin-based composite resin, dual-polymerizing resin-based composite resin, nanohybrid composite resin, and microhybrid composite resin) were fabricated and stored in red wine, black tea, chlorhexidine, sodium fluoride, tea tree oil, or distilled water for 4 weeks at 37°C. Color parameters were measured with a colorimeter before and after storage. Total color differences and specific coordinate differences were expressed as ΔE, ΔL, Δa, and Δb. A 2-way and 1-way analysis of variance (ANOVA) with Bonferroni adjustment for multiple comparisons were applied for statistical calculations (α=.05). RESULTS: Red wine caused the most severe discoloration (ΔE >10), followed by black tea with perceptible (ΔE >2.6) to clinically unacceptable discoloration (ΔE >5.5). Colored mouth rinses discolored the materials to a lesser extent with clinically acceptable values. Dual-polymerizing resin adhesives showed a higher amount of discoloration. CONCLUSIONS: Current restorative and adhesive composite resin materials discolor over time under the influence of different storage solutions. The composition related to the polymerizing mode seemed to be a causative factor.

Oral status among seniors in nine nursing homes in Styria, Austria.

OBJECTIVE: To investigate the oral state in participants cared for in residences for senior citizens in Styria, Austria. MATERIALS AND METHODS: Four hundred and nine participants in Styria from nine homes for senior citizens were examined employing parameters in accordance with those of Folstein's Mini Mental Status (MMS), DMFT, basic periodontal examination, the modified oral hygiene index, pain experienced during the preceding year, the subjective and objective need for treatment, and also requirements involving surgical and prosthetic treatment. Furthermore, the habitual methods of maintaining oral hygiene were examined establishing by whom this was carried out - whether by the patient, the nurse, or by patient and nurse together. RESULTS: Four hundred and nine participants were examined, 48.3% were found to have retained on average 4.9 of their own teeth while 69% were fitted with dentures; however, 81% of the participants required prosthetic treatment. 28.9% of the participants had experienced acute dental pain during the preceding year and surgical treatment was found to be necessary in 47.7% of those with original teeth. Eighty-four per cent of the participants showed acute inflammation of the periodontium while the state of oral hygiene, measured on a scale of 0-4, reached an average of 2.43. Oral hygiene was carried out by the nurses in only 7.46% of the cases which showed an average MMS measurement of 18. CONCLUSION: The results compared with those reported in other recent surveys and our data show an urgent need in Austria to improve the standards in dental care for the hospitalised elderly. Regular dental checks, carried out in the actual home by a dental surgeon should be introduced, whilst the nursing staff should be made fully aware of the problems caused by insufficient oral care and receive regular support from specialised oral hygiene assistants. The results of this survey also suggest that nursing staff should be equipped with simple instruments in order to judge to the extent to which the patient is capable of carrying out oral care independently and then according to the results to supplement this with additional care.