Crown cementation and pulpal health

Pulpal and periapical disease in crowned vital teeth: A prospective matched cohort study

This study aimed to determine the incidence and contributing factors to pulpal and periapical disease in crowned vital teeth. Seventy-three pairs of healthy teeth were included and divided into two groups; 'crowned' and 'untreated' groups. The crowned group was prepared for full coverage crown and no treatment was carried out on the untreated group. Both groups were subjected to clinical and radiographic examination to detect endodontic signs and symptoms pre-operatively and one-week after crown cementation. Electric pulp test was also subjected to both groups, pre-operatively, after tooth preparation and before crown cementation. The incidence of pulpal and periapical disease was 6.8% and 1.4%, respectively, after tooth preparation. Factors associated with pulpal and periapical disease were exposed pulp during tooth preparation and pre-operative bone level <35%. Despite the low incidence, the occurrence of pulpal and periapical disease within a short period is noteworthy.

In vivo and in vitro Permeability of One-step Self-etch Adhesives

Adhesive dentistry should effectively restore the peripheral seal of dentin after enamel removal. We hypothesize that non-rinsing, simplified, one-step self-etch adhesives are effective for minimizing dentin permeability after tooth preparation procedures. Crown preparations in vital human teeth were sealed with Adper Prompt, Xeno III, iBond, or One-Up Bond F. Epoxy resin replicas were produced from polyvinyl siloxane impressions for SEM examination. Dentin surfaces from extracted human teeth were bonded with these adhesives and connected to a fluid-transport model for permeability measurements and TEM examination. Dentinal fluid droplets were observed from adhesive surfaces in resin replicas of in vivo specimens. In vitro fluid conductance of dentin bonded with one-step self-etch adhesives was either similar to or greater than that of smear-layer-covered dentin. TEM revealed water trees within the adhesives that facilitate water movement across the polymerized, highly permeable adhesives. Both in vitro and in vivo results did not support the proposed hypothesis.

Effect of interim cement application on bond strength between resin cements and dentin: Immediate and delayed dentin sealing

STATEMENT OF PROBLEM

Despite the advances in materials and techniques, adhesion to dentin is challenging because of the complex composition of dentin's mineral, organic, and fluid phases.

PURPOSE

The purpose of this in vitro study was to evaluate the bond strength of 2 different resin cements (conventional and self-adhesive) with or without previous dentin sealing and the effect of interim cement.

MATERIAL AND METHODS

Forty-five molars were embedded into acrylic resin blocks and a flat dentin surface was exposed. Twenty teeth (n=5 per group) were treated with the conventional resin cement associated with etch-and-rinse or self-etch adhesive approaches, applied before (immediate dentin sealing) or after (delayed dentin sealing) the application/removal of interim cement. Another 25 teeth (n=5, per group) were treated with self-adhesive resin cement with (self-etch mode [immediate dentin sealing or delayed dentin sealing]) or without adhesive application. Furthermore, in the self-adhesive resin cement group, the application of polyacrylic acid for dentin etching before cementation was evaluated. Composite resin blocks were cemented onto flat, treated dentin surfaces, and the assemblies were sectioned into bar-shaped specimens for microtensile bond strength testing. The data were subjected to 1-way ANOVA followed by the post-hoc Tukey test (α=.05). The failure patterns were classified as cohesive, adhesive, or mixed.

RESULTS

The application of adhesive before interim cement (immediate dental sealing) promoted the highest values of bond strength for both resin cements (P<.001). For self-adhesive resin cement, polyacrylic acid-enhanced bond strength after the application of interim cement.

CONCLUSIONS

The application of dental adhesive immediately after tooth preparation (immediate dentin sealing) and before the use of an interim cement promoted the highest values of bond strength to dentin with the resin cements tested.

Effectiveness of desensitizing agents in relieving the pre- and postcementation sensitivity for full coverage restorations: a clinical evaluation

Patients frequently report sensitivity of prepared abutment teeth during the temporization period and after the fnal cementation of full coverage restoration. Purpose of this clinical investigation was to evaluate the effectiveness of desensitizing agents in reducing the pre- and postcementation sensitivity for full coverage restorations and to compare the relative effcacy of three in offce applied desensitizing agents in relieving the postcementation sensitivity with the use of glass ionomer luting cement.

MATERIALS AND METHODS

This study consisted of 30 patients requiring either full coverage restoration or 3 unit fxed partial denture. Total of 40 restorations (n = 40) were made and were randomly assigned into four groups comprising 10 restoration (n = 10) in each group. Group C control where no desensitizer application was done, group BB applied with BisBlock dentin desensitizer (Bisco Inc.), group ST applied with Systemp desensitizer (Ivoclar Vivadent), group GC applied with GC Tooth Mousse desensitizer (GC Asia). Desensitizer application was done immediately after the tooth preparation. Sensitivity of the tested abutment was determined by the patient response to cold, hot and bite stimuli and were recorded on visual analog scale (VAS). Sensitivity level scores was evaluated at 4 time intervals, i.e. 1 week after desensitizer application at baseline precementation appointment and others at 5 minutes, 1 day and 1 week postcementation appointment. VAS score data was statistically analyzed using one-way ANOVA followed by post hoc Tukey's test.

RESULTS

BisBlock and GC Tooth Mousse desensitizer resulted in statistically signifcant (p < 0.01) reduction in postcementation sensitivity of glass ionomer cement in comparison to Systemp desensitizer at 5 minutes, 1 week postcementation time interval with no statistical difference was seen between all desensitizer groups at 1 day postcementation. Application of BisBlock and GC Tooth Mousse desensitizer resulted in highly signifcant (p < 0.01) reduction in sensitivity level at the end of 1 week.

CLINICAL SIGNIFICANCE

Desensitizer's application on the prepared abutment teeth is considerably effective in relieving both pre- and postcementation sensitivity for full coverage restoration over the short duration of time. Immediate reduction in postoperative sensitivity relatively in a short time period may be benefcial in terms of patient's comfort. Nonetheless, multicenter long-term clinical trials should be conducted to confrm the results.

CONCLUSION

Efficacy of BisBlock and GC Tooth Mousse desensitizer was more in relieving the postcementation sensitivity of glass ionomer cement at various time intervals in comparison to Systemp desensitizer. In conclusion, application of desensitizers was beneficial to reduce the pre- and postcementation abutment sensitivity.

Single-bottle adhesives behave as permeable membranes after polymerization. I. In vivo evidence

OBJECTIVES

This study tested the hypothesis that single-bottle total-etch adhesives are effective in reducing dentine permeability under in vivo conditions.

METHODS

Crown preparations on vital human teeth were performed under local analgesia as part of the treatment plan for prosthetic rehabilitation. Four single-bottle adhesives (Single Bond, 3M ESPE; Excite DSC, Ivoclar Vivadent; Prime and Bond NT Dual-Cure, Dentsply DeTrey and One-Step, Bisco Inc.) were applied to the cut dentine after acid-etching. Polyvinyl siloxane impressions were taken, using an ultra-low viscosity impression material, of the smear layer-covered dentine before applying the adhesives to deep vital dentine, and after adhesive placement. Additional impressions were taken of the adhesive-sealed dentine following the removal of the provisional prostheses after a 7-10 day period. Epoxy resin replicas of the crown preparations were examined with scanning electron microscopy to evaluate the extent of dentinal fluid transudation during pre-bonded, immediately bonded and post-bonded periods.

RESULTS

Dentinal fluid transudation from localised areas that were close to the dental pulp was universally observed from all epoxy resin replicas, irrespective of the adhesive employed. The transudation of dentinal fluid from the control smear layer-covered dentine of each crown preparation was comparatively mild when compared to the extent that was observed after total-etching and application of the single-bottle adhesive. Dentinal fluid droplets were specifically located over the surface of the adhesive layer. Continuous transudation of dentinal fluid occurred even after the removal of the provisional prostheses, and was considerably more profuse in subjects who opted for the fitting of the permanent prostheses without the use of a local anaesthetic solution.

CONCLUSION

Single-bottle adhesives, because of their lack of a comparatively more hydrophobic bonding resin layer, behave as permeable membranes after polymerisation. They permit the continuous transudation of dentinal fluid and do not provide a hermetic seal in vital deep dentine. Although the relatively slow rate of diffusion of dentinal fluid is unlikely to result in post-operative cold sensitivity, it may interfere with the optimal polymerisation of dual-cured or auto-cured composites or resin cements in both direct and indirect restorations.

Postcementation hypersensitivity: scientific data versus dentists' perceptions

PURPOSE

The purpose of this article was to obtain dentists' opinions via an Internet survey as to the prevalence, causes, and prevention of postcementation sensitivity and compare their responses with published data on the problem.

MATERIALS AND METHODS

Information as to respondents opinions of postcementation sensitivity was obtained from an Internet survey asking about their experience and for a ranking of the importance of each of 15 factors.

RESULTS

A total of 466 valid responses were received. The incidence of postcementation sensitivity was estimated to be less than 2% by more than 2/3 of the dentists. The factors considered "very important" in reducing sensitivity by more than 50% of the respondents were desiccation, luting agent, occlusion, provisional, and water spray.

CONCLUSIONS

Comparing respondents' opinions with published clinical studies, the incidence of postcementation sensitivity appears to be underestimated. There is little published evidence to support the importance of antimicrobials, desensitizing, or bonding agents, although these are considered effective by some dentists. Many respondents consider luting agent to be an important variable.

Micro-tensile bond testing of resin cements to dentin and an indirect resin composite

OBJECTIVES

Micro-tensile bond strength (microTBS) evaluation and fractographic analysis were used to compare four resin cement systems (AC: All-Bond 2/Choice; RX: Single Bond/RelyX ARC; SB: Super-Bond C & B; and PF: Panavia F) in indirect composite/dentin adhesive joints.

METHODS

Flat dentin surfaces were created on extracted human third molars. The resin cements were used according to the manufacturers' instructions for bonding silanized composite overlays to deep coronal dentin. 0.9x0.9 composite-dentin beams prepared from the luted specimens were stressed to failure in tension. Dentin sides of all fractured specimens were examined by scanning electron microscopy (SEM) to examine the failure modes. In group PF, morphologic features that could not be resolved at the SEM level were further validated by transmission electron microscopy (TEM) examination of the SEM specimens.

RESULTS

Statistical analyses revealed significant difference (p<0.05) among microTBS and failure modes in the resin cement groups. The two groups (AC and RX) with highest microTBS failed predominantly along the composite overlay/cement interface. Cohesive failure in resin cement was primarily observed in group SB that exhibited intermediate microTBS values. In group PF with the lowest microTBS, failure occurred mostly along the dentin surface. Globular resin agglomerates seen by SEM on PF-treated dentin were distinguished from silica fillers by TEM.

SIGNIFICANCE

The bond between the processed composite and the luting resin cement was the weak link in indirect composite restorations cemented with AC or RX. Super-Bond C&B exhibited intermediate tensile strength and Panavia F is less reliable when used in conjunction with a self-etching primer for bonding indirect restorations to dentin.