Quintessence International, 09/1991

Many clinicians advocate etching the teeth before vital bleaching as a way to enhance the permeability of the tooth surface to hydrogen peroxide and thus to enhance the bleaching effect. However, no studies have been published to date to document the effect of etching on vital bleaching. In this study, ten patients received a bleaching treatment regimen of several appointments. Half of the teeth in one arch of each patient were etched with phosphoric acid for 20 seconds before they were bleached with 35% hydrogen peroxide. The teeth in the other half of the same arch were treated with tap water prior to bleaching. Evaluations of the patients after 3 and 6 weeks failed to confirm any enhanced lightening effect from etchin

One hundred sixteen cervical abrasion/erosion lesions were restored with one of the following techniques: (1) glass-ionomer cement, (2) composite resin with a dentinal bonding agent, or (3) composite resin with a glass-ionomer cement liner and a dentinal bonding agent. The restorations were assessed at baseline and at 6 months and 1 year postrestoration for retention, caries, color match, marginal staining, and surface texture. No statistically significant differences were found in retention, caries, color match, or marginal staining. A statistically significant difference was found with regard to surface texture: glass-ionomer cement restorations demonstrated a rougher surface than did the composite resin restorations. A substantial number of restorations composed of composite resin with a dentinal bonding agent demonstrated a color shift towards mismatch when evaluated at 6 months. This difference was not significant at the 1-year followup.

This paper describes the clinical and laboratory stages necessary to ensure the occlusal precision of fixed restorations. The important diagnostic stages, including elimination of mandibular dysfunction, the occlusal analysis and waxing of diagnostic casts, and the diagnostic use of provisional restorations, are outlined. The importance of having the clinician control all stages of laboratory work, including die trimming, mounting working casts on an articulator, the determination of both anterior and posterior tooth form, and the final occlusal adjustment of the restorations, is emphasized.

Visible light-curing interpenetrating networks are newly developed materials suitable for several dental applications. These materials have several advantages, including versatility and good physicomechanical properties, but also present some weaknesses, such as increased water sorption and poor adhesion to plastic teeth. The suitability of a visible light-curing resin as a repair material, ie, its bending strength, was examined. Results were compared to those obtained with a self-curing acrylic resin. The visible light-curing resin led to repairs with lower strength.

Vertical root fracture presents a diagnostic problem, and treatment is not usually successful. This case report demonstrates use of calcium hydroxide paste to induce healing of fractured roots. Glass-ionomer cement was used as a root canal sealer and then condensed into the root canals to bind the segments together.

A review of aging of dental components is followed by a clinical radiographic study. Patients received radiographs at 5-year intervals with a 10-year minimum followup. Data obtained were age, gender, tooth, and systemic diseases. Measurements taken were tooth length, coronal length, apical length, cervical width, midroot width, and apical width. Root canal shrinkage was caluclated vertically, horizontally, and as a combination (vertical and horizontal). Results showed statistically significantly more shrinkage in men, the elderly, and people with calcification-related diseases. Shrinkage increased with advancing age. With further studies, radiographically determin ed root canal measurements could prove useful in anthropology, forensics, and as a biomarker of aging.

The efficacy of a dental unit equipped with a system that disinfects and sterilizes the water tubing by flushing with glutaraldehyde was evaluated by inserting Bacillus megaterium spores and Pseudomonas and Moraxella species into the water tubing. Up to 10 to the 8th power Pseudomonas a nd Moraxella organisms were killed during the disinfection cycle, but Bacillus megaterium spores were not. Up to 10 to the 5th power spores were eradicated by the sterilization cycle, although the system did not consistently kill 10 to the 8th power spores. The water tubing of the new unti was not naturally colonized by water bacteria during an 8-month period prior to the study. Evidence suggested that this was due to antimicrobial activity associated with the plastic tubing: therefore, microbial contamination of new dental units, irrespective of their design, would not be expected, until the inhibitory factor in the plastic tubing has leached out.

Control of bacterial plaque on tooth surfaces i the most important method of controlling dental disease. The patient's ability to achieve good plaque control is of utmost importance in preventing the occurrence of periodontal disease and in maintaining periodontal health. The search for better methods that enable earier and more effective plaque control has led to the development of the chewing wheel. A clinical trial was conducted to compare the plaque-removing efficiency of the chewing wheel to that of a manual toothbursh. The tested device removed 18% to 37% of the accumulated dental deposits. In spite of its limited efficiency, the wheel can be used as part of an oral hygiene program for individuals with perceptomotor dysfunctions.

The purpose of the present study was to evaluate the color stability of selected indirect composite ersins. Twenty-six specimens each of Dentocolor, VisioGem, Brilliant D. I., and Concept were fabricated and immersed in chlorhexidine, coffee, and tea. The modifying effect of saliva on staining was also studied. Coffee and tea both stained the tested materials, but tea stained more than coffee. The addition of chlorhexidine and saliva increased staining when used with tea. Most staining was superficial and could be removed with regular oral hygiene; however, residual staining, which might become cumulative, was recorded. Brilliant D. I. samples exhibited the most discoloration and Concept samples the least.

The purpose of this study was to examine the effectiveness of glycerine gels in preventing the formation of an oxygen-inhibition layer during the polymerization of composite resin materials. Sixteen glass-ceramic inlays were adhesively luted with and without the application of glycerine gels on the inlay margins before the polymerization of the luting composite resin material. To remove the oxygen-inhibition layer, the inlays were brushed with acetone. Replicas were obtained before and after acetone brushing, and a computerized quantitative marginal analysis was carried out under the scanning electron microscope. Statistical analysis revealed significant differences between the polymerization with and the polymerization without the use of a glycerine gel. The inlay margins polymerized after the application of a glycerine gel showed better marginal adaptation than did the inlay margins polymerized without it, suggesting that oxygen inhibition during polymerization can be prevented by the application of glycerine gels to the surface of composite resin materials.

The purpose of this investigation was to evaluate the effects of time of storage and thermocycling on the shear bond strength of three dentinal adhesives. The shear bond strength of Mirage Bond was signficantly greater than that of Scotchbond 2, which was significantly greater than that of Scotschbond Dual Cure (P - .05). Thermocycling signficantly lowered the shear bond strength of Scotchbond Dual Cure and Scotchbond 2, but not that of Mirage Bond (P - .05). Time of storage did not affect the shear bond strength of the other adhesives, but Mirage Bond had a significantly greater shear bond strength after 1 month of storage (P - .05). Scanning electron microscopic observations showed that the fracture patterns were all at the smear layer-adhesive interface for scotchbond Dual Cure, the majority of the fractures were at the primer-adhesive interface for Scotchbond 2, and most of the fractures were cohesive in the bonding agent for Mirage Bond.

To ascertain the role of Candida in denture stomatitis, the practitioner must conduct a mycologic examination of the acrylic resin denture surface, because it acts as a reservoir for continuous reinfection of the palate. Twenty-two patients were examined to compare the sensitivity of the standard technique of swabbing the denture to that of a newly developed cast agar replica technique for detecting Candida albicans. The dentures were swabbed and cast replicas of the tissue-fitting surface of the dentures were made of both study populations. The majority of cultures obtained by swabbing failed to detect the presence of Candida albicans, while all cast agar replicas grew Candida albicans. The replica mthod for the detection of Candida albicans in edentulous patients seemed to be a more sensitive method than currently available mycologic methods.