In vitro tooth color change with repeated bleaching.

The interest of patients in vital tooth bleaching has created a demand for treatment. However, few objective data are available to help determine the number of bleaching appointments necessary and the lightening that can be expected. The purpose of this study was to measure color changes in bleached extracted teeth and compare these to control groups. Group A was etched and bleached with 35% stabilized hydrogen peroxide. Group B was treated the same as group A, but the bleaching solution was replaced with distilled water. Group C was not treated, but was stored in water. Mean color difference after one treatment was 3.33 for group A, 1.67 for group B, and 0.48 for group C. After six treatments, the overall color difference was 3.82, 2.41, and 1.38 for groups A, B, and C, respectively (P less than .01). Color changes beyond those found after the first treatment were small, suggesting that there was little benefit in repeated bleachings under the conditions of this study.     

Enhanced osseointegration of hydroxylapatite implant material.

This study was undertaken to determine whether the addition of calcium sulfate to hydroxylapatite (HA) implant material would improve its working properties without adversely affecting its osseointegration. The clinical and histologic examinations of bone response of three implant materials, hard tissue replacement (HTR), HA, and HA composite (HA plus calcium sulfate), were performed after 2-, 4-, and 6-week implantation in tibia and mandible of rabbits. No sign of extensive chronic inflammatory response was detected. The highest rate of bone ingrowth occurred with the HA composite, followed by HA, with HTR showing the least ingrowth. Bone was deposited directly on the surface of HA and HA composite implant materials. In contrast, HTR particles had a thin layer of fibrous tissue encapsulation with the normal bony investment.     

KVP meter errors induced by plastic wrap

The purpose of this study was to determine whether erroneous kVp meter readings, induced by plastic wrap, affected the actual kVp (output) of a dental X-ray machine. To evaluate the effect of plastic wrap on dental X-ray machine kVp meters, a radiation output device was used to measure output in mR/ma.s. An intraoral dental X-ray unit (S.S. White Model #90W) was used to make the exposures. First, the kVp meter was not covered with plastic wrap and output readings were recorded at various kVp settings with the milliamperage and time held constant. Secondly, the same kVp settings were selected before the plastic wrap was placed. Milliamperage and time were again held to the same constant. The X-ray console was then covered with plastic wrap prior to measuring the output for each kVp. The wrap possessed a static charge. This charge induced erroneous kVp meter readings. Out-put readings at the various induced kVp settings were then recorded. A kVp of 50 with no wrap present resulted in the same output as a kVp of 50 induced to read 40 or 60 kVp by the presence of wrap. Similar results were obtained at other kVp settings. This indicates that the plastic wrap influences only the kVp meter needle and not the actual kilovoltage of the X-ray machine. Dental X-ray machine operators should select kVp meter readings prior to placing plastic wrap and should not adjust initial settings if the meter is deflected later by the presence of wrap. The use of such a procedure will result in proper exposures, fewer retakes, and less patient radiation. If plastic wrap leads to consistent exposure errors, clinicians may wish to use a 0.5% sodium hypochlorite disinfectant as an alternative to the barrier technique.     

Diagnosis of alveolar bone changes with digital subtraction images and conventional radiographs. An in vitro study

The purpose of the present study was to compare the diagnostic properties of radiographs obtained with Ultra-Speed and Ektaspeed films when analyzed conventionally radiographs and after conversion in digital subtraction images. Artificial lesions, measuring 0.5, 0.7, 0.9, and 1.1 mm in diameter, were drilled in a dry skull with slow-speed burs. Standardized radiographs were obtained by means of acrylic bite blocks and a modification of the Rinn system. The results of this study demonstrated that sensitivity in the detection of the lesions was doubled after digitizing and displaying subtraction images compared with the conventional radiographic interpretation, independent of the use of Ektaspeed or Ultra-Speed films for the original radiographs. The diagnostic information seemed to be equal in radiographs obtained from Ultra-Speed and Ektaspeed films after digitization and image processing procedures.     

Effect of mouthrinsing after toothbrushing with a fluoride dentifrice on human salivary fluoride levels

In a recent clinical trial of sodium monofluorophosphate dentifrices, oral rinsing habits were found to influence dental caries. Thus an oral fluoride clearance study has been undertaken which was designed to test a possible mechanism for the observed effects. Eight subjects brushed with one of the trial dentifrices and then rinsed using 1 of 8 procedures of varying thoroughness. The salivary fluoride concentration measured 5 min after dentifrice application decreased significantly with increasing rinse volume, rinse duration, and rinse frequency (p less than 0.01, analysis of variance). The area under the clearance curve determined over a further 3 h was significantly higher (300%; p less than 0.01) following use of the least thorough rinsing procedure (5 ml x 2 s once) as compared with the corresponding area under the clearance curve following the most thorough procedure (20 ml x 10 s twice). These findings indicate that rinsing habits may play an important role in the oral retention of fluoride from dentifrices which may, in turn, affect their clinical efficacy.     

Treatment of severe chemomechanical erosion using castable ceramic restorations and a new dentin/enamel bonding system: a case report

Six maxillary anterior teeth demonstrating severe chemomechanical erosion were restored using a minimal preparation design and a castable ceramic. Facial and lingual erosion prevented the development of the opposing wall retention and resistance form needed for traditionally cemented ceramic or porcelain-fused-to-metal crowns. Therefore, a dentin/enamel bonding system was used to condition the enamel and dentin simultaneously prior to cementation of an etched and silanated castable ceramic restoration. A resin cement was used as the luting agent.     

Orthodontic considerations applied to craniofacial dysmorphology

The contemporary management of patients with craniofacial anomalies involves a team approach of multiple specialists. Interaction between the basic scientist, developmental biologist, and the clinician should be an important aspect of interdisciplinary research if clinically relevant questions are to be addressed under rigorous laboratory conditions. The clinical investigator may be unfamiliar with the terminology and methodology of basic biomedical research. As a result, there can be a lack of communication between the clinician and the basic scientist. The role of the orthodontist in a multidisciplinary craniofacial team has evolved largely from an interest in dysmorphology as applied to craniofacial growth and development. The predictability of orthognathic surgery has been derived from the close collaboration between the orthodontist and surgeon and may be applied to the more comprehensive management of patients with craniofacial anomalies. To determine the mechanisms underlying the pathogenesis and response to treatment will require a collaborative approach by the clinician and research scientist to elucidate causal and putative risk factors in the complex genetic and environmental associations involved in craniofacial anomalies.     

Connective tissue-associated proteins in crevicular fluid: potential markers for periodontal diseases

Tests for periodontal disease that are able to detect both ongoing and future loss of clinical attachment would be valuable assets in determining the diagnosis and treatment of periodontal diseases. We hypothesized that connective tissue-associated proteins could be detected in crevicular fluid and would reflect the biochemical activity of the periodontium in health and disease. To test this hypothesis, crevicular fluid samples obtained from patients with various states of periodontal disease were analyzed for the presence of several connective tissue-associated proteins using a dot blot assay. Two such proteins, osteonectin and N-propeptide alpha I type I collagen, were detected in crevicular fluid samples of patients with periodontal disease. Furthermore, the amount of these proteins detected in crevicular fluid appeared to increase with increased probing depth at the sampled site. These studies indicate that measurements of connective tissue-associated proteins in crevicular fluid may prove to be a valuable tool for diagnosing periodontal diseases.     

Clinical enhancement of post-periodontal surgical therapy by a 0.12% chlorhexidine gluconate mouthrinse

Previous studies have demonstrated the potential beneficial effects of post-surgical rinsing with 0.2% chlorhexidine. In the present investigation a new chlorhexidine formulation (Peridex) (CHx) and concentration (0.12%) was evaluated clinically to determine if similar effects could be detected from the use of the new product and treatment regimen. A double blind, randomized, placebo-controlled study was carried out in 40 patients during a 6 week period. Patients who had moderate periodontitis (AAP Class III) received osseous periodontal surgery in one quadrant. Each surgical site received periodontal dressing and patients were given a placebo or CHx mouthrinse to be used twice each day. Compared to placebo, CHx significantly reduced plaque at all examinations (54.4% reduction over placebo at 6 weeks, P less than 0.05). Visible plaque (PlI greater than 2) in the CHx group was reduced by 99% over the placebo group at 6 weeks and at 4 weeks post-surgical, gingival inflammation scores were significantly lower in the CHx group (17% reduction over the placebo at 4 weeks, P less than 0.05). Gingival bleeding scores (GI greater than 2) were significantly lower in the CHx group at 4 and 6 weeks (41% and 40% reduction over the placebo group, P less than 0.05). Probing pocket depth and attachment level changes were not significantly different between both groups. Epithelialization rates and pain assessment demonstrated consistently better results in the CHx group, although differences were not statistically significant. Use of 0.12% chlorhexidine immediately following periodontal surgery, for 6 weeks, has been shown to be a clinically effective adjunct providing enhancement of the post-surgical management of periodontal surgical patients.     

Bactericidal effect of a disinfectant dental stone on irreversible hydrocolloid impressions and stone casts

Infection control in dentistry focuses on the prevention of cross-contamination among patients, dentists, and dental auxilary personnel. This study evaluated the bactericidal effect of a dental gypsum material containing 0.25% chloramine-T on oral irreversible hydrocolloid impressions and dental casts. Eighty irreversible hydrocolloid impressions from 40 human volunteers were prepared. Forty impressions were poured with the disinfectant dental stone and a similar number were poured with a comparable, nondisinfectant stone. After setting for 60 minutes, the impressions and separated casts were sampled for bacterial contamination. The disinfectant stone inhibited bacterial growth in 39 of 40 impressions and casts, whereas all casts and impressions poured with the nondisinfectant stone were contaminated. The disinfectant dental stone containing chloramine-T was effective in eliminating bacterial contamination of both the irreversible hydrocolloid impression and stone cast.