G. Lynn Powell

The accuracy and efficacy of disinfection by spray atomization on elastomeric impressions.

Five disinfectants applied by spray atomization were examined for possible dimensional distortion of elastomeric impression materials, polyether, polysulfide, and addition silicone, and the associated improved, type IV gypsum casts. The disinfectants did not affect, in a clinically significant manner, the three dimensions measured with an instrument accurate to 1 micron on improved gypsum casts that reproduced a stainless steel standard. The master cast represented two teeth of a fixed partial denture prepared for complete veneer retainers. The use of control casts from elastomeric impressions that were not treated with the disinfectants further supported previous investigations reporting the accuracy of dental casts as the function of the impression material. The use of a spray disinfectant will not appreciably alter the dimensional accuracy of improved stone casts made within elastomeric impressions. The most accurate stone cast system was produced by addition silicone impressions disinfected by a surface spray. It was also shown that four of the disinfectants applied by spray atomization were effective in disinfecting the surface of an elastomeric impression material contaminated with selected test organisms.

Enamel caries initiation and progression after argon laser irradiation: In vitro argon laser systems comparison

OBJECTIVE The purpose of this in vitro laboratory study was to determine the effect of low-fluence argon laser (AL) irradiation delivered from two different argon laser systems on enamel caries-like lesion initiation and progression. BACKGROUND DATA Previous in vitro investigations and a recent in vivo pilot study have shown that AL irradiation of enamel provided a protective effect against in vitro and in vivo cariogenic challenges. MATERIALS AND METHODS Twenty extracted human molars were selected, and 10 teeth were assigned to the HGM argon laser group and 10 were assigned to the LaserMed argon laser group. The exposed buccal windows of sound enamel were exposed to low-fluence irradiation, while the lingual windows of enamel were not exposed to laser irradiation and served as the no-treatment (control) group. Enamel caries-like lesions were created using an acidified gel. Two longitudinal sections were taken per sample (n = 20 lesions per group) and evaluated by polarized light microscopy for body of the lesion depths after lesion initiation (8 weeks) and progression (12 weeks) periods. RESULTS After lesion initiation and progression, the body of lesion depths were similar for both argon-irradiated groups (p > 0.05). With the no-treatment (control) group, there were significant increases in lesion depth with a 61-78% increase for the lesion initiation period and a 50-69% increase for the lesion progression period when compared with the argon laser-treated groups. CONCLUSION Argon laser irradiation provides a certain degree of protection against in vitro enamel caries initiation and progression. Resistance to a continuous caries challenge was similar with either argon laser delivery systems (HGM and LaserMed). Argon laser irradiation may prove to be beneficial in reducing the caries susceptibility of sound enamel and white spot lesions in the clinical environment.

Laser dental decay prevention: does it have a future?

Previous studies have recorded the reduction of caries-like lesions or demineralization in extracted human teeth that have been irradiated using CO2, Nd:YAG and Argon lasers, with CO2 or Argon showing up to 40 - 50% reduction. By adding a chemical inhibitor, such as DAC or fluoride to lasing procedures, the demineralization can be reduced 60 - 80%. Studies have demonstrated the laser safety for Argon and CO2 laser in these procedures. Clinical trials are being initiated to evaluate acid resistance of enamel exposed to laser radiation. This presentation will review prior results and present our current findings.

Brain abscess of odontogenic origin: report of case

Advanced dental infection rarely causes brain abscess resulting in death. Good dental hygiene and removing abscessed teeth are advised for prevention of any such occurrence. An intercranial infection is described in a 29-year-old male who also had a dental phobia.

Comparison of three lasers on demineralization of human enamel

Previous studies have recorded the reduction of caries-like lesions or demineralization in extracted human teeth that had been irradiated with CO2 laser, Nd:YAG laser, and Argon laser. This study was conducted to evaluate the effects of three different cw lasers on acid resistance and demineralization of dental enamel. Human enamel was laser irradiated with either Argon, CO2, or Nd:YAG energy densities of 60 - 65 J/cm2 or 120 - 130 J/cm2. The amount of demineralization was determined in a rotating disk assembly (0.1 M acetate buffer, pH - 4.5) for 24 hours and the results determined and plotted against the non-lased control using microradiographs and computerized imaging. The amount of dissolution of tooth structure lost to demineralization in 4.5 pH acid bath in a 24 hour period was reduced from approximately 140 microns for the unlased control to approximately 90 microns for the Argon laser and 70 microns for the CO2 laser at 60 - 65 J/cm2. At 120 - 130 J/cm2 the results were: 120 microns for the Nd:YAG, 70 microns for the Argon, and 45 microns for the CO2 laser. This study shows that demineralization is reduced significantly in vitro when human enamel is exposed to Argon and CO2 laser irradiation.

Er:YAG clinical results on hard tissue: phase II

Objective: This study was performed in order to establish that the pulpal and dentinal tissue are safe when exposed to the 2.94 micron pulsed Er:YAG laser radiation for the procedures of caries removal, cavity preparation, and etching prior to acid etching. This presentation discusses the histological results of a double-blind study comparing a pulsed Er:YAG with a standard dental drill. Methods: A double-blind histological evaluation of the pulpal and dentinal tissue changes induced by the Erbium laser and the dental drill was conducted on teeth extracted immediately following the dental procedure and at various intervals up to 1 year post-treatment. A statistical analysis was used to determine if any statistically significant clinical differences in dental tissue response could be observed between the Er:YAG laser and the standard dental drill. Conclusions: Analysis of the results indicated there were no significant differences observed between the laser and control groups in this study.