Effect of different protective base materials on hydrogen peroxide leakage during intracoronal bleaching in vitro.

External root resorption may develop following intracoronal bleaching with hydrogen peroxide. The preventive effect of different base materials on the radicular penetration of H2O2 during intracoronal bleaching was assessed. Seventy-two bovine teeth and 20 human teeth were bleached with 30% H2O2. The bovine teeth were divided into four groups and the root canals filled with either IRM, zinc oxide-eugenol, composite resin, or glass ionomer. The radicular H2O2 penetration of each group at different layer thickness was compared. The experiment with the human teeth was performed in three stages. In the first stage no protective base was used. In the second stage IRM was placed to the cementoenamel junction level. In the third stage the IRM layer was removed 0.5 mm below the cementoenamel junction. None of the materials tested in the bovine teeth showed H2O2 penetration with a base thickness of 2 mm. When the base thickness was reduced to 1 mm, several teeth showed H2O2 penetration; however, there was no significant difference among the materials tested. When the base thickness was reduced to 0.5 mm, the H2O2 penetration in each group increased. A statistical difference was found between the composite and the glass ionomer (p < 0.05). The results for the human teeth showed that IRM layer placed at the cementoenamel junction level significantly reduced the radicular H2O2 penetration as compared with teeth where the IRM was either placed 0.5 mm below the cementoenamel junction or not placed at all (p < 0.01). It is therefore recommended that a protective base be placed to the cementoenamel junction level before intracoronal bleaching to prevent possible H2O2 hazards.

Marginal leakage around V-shaped cavities restored with glass-ionomer cements: an in vitro study.

The object of this investigation was to assess the degree of marginal leakage around V-shaped cervical glass-ionomer cement restorations and compare it to that around composite resin restorations. Three different glass-ionomer cements and one composite resin control were assessed by means of dye penetration. Severe microleakage at the occlusal margins was found in 70% of the glass-ionomer cement restorations, but in only 10% of the composite resin restorations. A considerable amount of dye penetration was observed at the cervical margins of all restorations, including the controls. None of the glass-ionomer cements tested showed superiority in preventing marginal leakage occlusally or gingivally.

Orthodontic forced eruption: case report of an alternative treatment for subgingivally fractured young permanent incisors.

Subgingivally fractured incisors are still a challenge to treat. A case report is used as a basis for reviewing the different treatment options, which involve either extraction or preservation of the root. A multidisciplinary approach, using orthodontic forced eruption, is presented in detail.

One-year clinical evaluation of an anterior composite resin.

An anterior composite resin was evaluated in a clinical study of 93 Class III and Class IV restorations placed in patients aged 12 to 50 years. The restorations were evaluated at baseline, 6 months, and 1 year. Sixty-four (79%) of the 81 restorations examined at the 1-year recall were unchanged. Marginal discoloration and changes in surface appearance and marginal adaptation accounted for most of the changes. All changes appeared in patients younger than 14 years, which may indicate that the patients had problems in oral hygiene. Replicas of randomly selected restorations showed smooth surfaces and well-sealed margins with a smooth transition from restoration to enamel. Some restorations showed marginal breakdown and a pitted irregular surface.

Effect of etching on leakage of sealants placed after air abrasion.

PURPOSE: The aim of the present study was to assess the microleakage of pit and fissure sealants in: 1) air-abraded molars with and without etching and 2) in preventive resin restorations (PRR) prepared with air abrasion or mechanically with a bur. METHODS: Forty molars with no or minimal occlusal caries were cleaned with pumice, washed, and assigned to four groups of 10 teeth each. In group A, the teeth were air-abraded and Helioseal was applied directly to the fissures without previous treatment. Group B was air-abraded and etched for 20 s prior to sealant application. In group C, caries was excavated with air abrasion, etched, and restored with Scotchbond Multipurpose, Z-100 and Helioseal. Group D was similar to C except that the fissures were prepared mechanically with a carbide bur at high speed. RESULTS: Group A was significantly different in both Y1 and Y2 measurements from all the other groups. No differences were observed between all the other groups. Acid etching should be a precondition before sealant application. Air abrasion and mechanical preparation resulted in the same amount of microleakage following acid etch.

Acid-etched and erbium:yttrium aluminium garnet laser-treated enamel for fissure sealants: a comparison of microleakage.

OBJECTIVES: A pilot study aimed to compare the microleakage of pit and fissure sealants in acid-etched and Erbium:Yttrium Aluminium Garnet (Er:YAG)-treated enamel. METHODS: Forty permanent noncarious young molars and premolars, which were extracted for orthodontic reasons, were selected. The teeth were divided into four groups, with five molars and five premolars in each group. The groups were treated as follows: (1) group A--laser irradiation of the enamel of the occlusal surface without contact and in scanning mode was carried out using an Er:YAG laser, placement of sealant material, light curing, and thermocycling between 6 degrees and 55 degrees C; (2) group B--the same as group A, but with no thermocycling; (3) group C--acid etching of the enamel surface, placement of sealant material, light curing and thermocycling; and (4) group D--the same as group C, but with no thermocycling. After being immersed in 1% methylene blue solution, all teeth were sectioned in the mesio-distal dimension into four slices. Images of the slices were then scanned to a Macintosh G3 computer and examined for marginal leakage. Leakage was measured by the degree of dye penetration. Three independent examiners evaluated the dye penetration. RESULTS: No penetration of dye material was observed in any of the slices in any of the four groups by any of the examiners. CONCLUSIONS: No difference in microleakage was seen between lasing or acid etching, and therefore, the results of the present study would suggest that the technique may be efficacious.

Inhibition of plaque accumulation under periodontal dressing by sustained-release varnish of chlorhexidine.

Slow-release varnish containing chlorhexidine was applied prior to the application of a periodontal dressing. The ability of the slow-release varnish to inhibit accumulation of dental plaque under the dressing was compared to a placebo varnish. Seven volunteers were fitted with periodontal dressing on the lower and upper jaws. One jaw was pre-coated with slow-release varnish containing chlorhexidine, while the other was coated with a placebo. A week later the dressings were removed and the plaque under the dressing was scored. Significantly less plaque was found on teeth pre-coated with the slow-release varnish containing chlorhexidine as compared to the control. An increase in the amount of gingival fluid was observed in both the control and experimental groups after removing the periodontal dressing.

Marginal leakage of class II glass ionomer-composite resin restorations: an in vitro study.

This in vitro study assessed the sealing properties of two metal-reinforced glass ionomer cements, used as "extended bases" in glass ionomer-composite resin restorations. Two class II cavities were prepared in the proximal surfaces of 30 molars. The gingival margin of one was prepared in enamel and the other in cementum/dentin. Fifteen teeth (30 cavities) were restored with Ketac Silver material used as an extended base (group A). In the remaining 15 teeth (30 cavities), the extended base was in Miracle Mix material (group B). All occlusal surfaces were restored with Estilux Posterior Material. The restored teeth were thermocycled, immersed in fuchsin, washed in water, embedded, sectioned, and examined under a dissecting microscope. All restorations with margins in cementum/dentin of group A (Ketac Silver) leaked. No microleakage occurred in 12 of the 30 restorations with margins in cementum/dentin of group B (Miracle Mix). In addition, severe microleakage was present in 24 teeth of group A, as opposed to three in group B. It was concluded that the sealing properties of Miracle Mix material are superior to those of Ketac Silver material, in vitro.

The effect of sustained release application of chlorhexidine on salivary levels of Streptococcus mutans in partial denture wearers.

The effect of a slow-releasing dosage (SRD) coating of chlorhexidine on the salivary levels of Streptococcus mutans and on plaque index scores in patients with removable partial dentures (RPD) was tested. The SRD proved to be effective in maintaining a low level of S. mutans counts after mechanical cleaning, as compared to a baseline established during the control period. Plaque index scores were lower following the treatment and correlated with the microbiological results. Our findings indicate that a single application of sustained-release chlorhexidine to removable partial dentures effectively maintains S. mutans levels as well as reducing the plaque score for a minimum period of 1 week.