Nd:YAG laser effects on the occlusal surface of premolars

PURPOSE

To evaluate with the scanning electron microscope (SEM) the effects of a pulsed Nd: YAG laser on the occlusal surface of human premolars in vitro.

MATERIALS AND METHODS

Twenty normal premolars extracted for orthodontic reasons were used and separated in two groups. Group 1 received the irradiation at 2.0 watts, repetition rate of 20 Hz and 124.3 J/cm2 of energy density during 3 minutes, on the occlusal fissure. Group 2 received the laser irradiation in only half of the fissure.

RESULTS

The SEM analysis revealed that in the case of shallow fissures the sealing was total but in narrow and deep fissure the sealing was partial or was in complete.

A comparison of three resin bonding agents to primary tooth dentin

This study determined the shear bond strength of resin composites to primary dentin using three dentin adhesives and the presence or absence of a hybrid zone. The buccal and lingual surfaces of 40 recently extracted noncarious primary teeth were ground flat with SiC paper ending with the 600 grit. The teeth were divided at randomly into eight groups of five teeth (10 surfaces) each: 1) Unetched dentin, dry dentin, All-Bond 2/Bis-Fil P; 2) Unetched dentin, moist dentin, All-Bond 2/Bis-Fil P; 3) Dentin etched for 15 sec with 10% phosphoric acid, dry dentin, All-Bond 2/Bis-Fil P; 4) Dentin etched for 15 sec with 10% phosphoric acid, moist dentin, All-Bond 2/Bis-Fil P; 5) Dentin etched with 10% maleic acid for 15 sec, dry dentin, Scotchbond Multi-Purpose/Z100; 6) Dentin etched with 10% maleic acid for 15 sec, moist dentin, Scotchbond Multi-Purpose/Z100; 7) Dentin etched with 10 citric acid/3% ferric chloride, dry dentin, Amalgambond Plus/Z100; 8) Dentin etched with 10 citric acid/3% ferric chloride, moist dentin, Amalgambond Plus/Z100. All teeth were thermocycled 1000x (5 and 55 degrees C, 30-sec dwell time), and shear bond strength testing was conducted using an Instron (crosshead speed 0.5 mm/min). Failure sites after debonding were examined with the SEM. For each group, one additional tooth was used to prepare two class V cavities (one facial and one lingual) restored according to the specification in each group, sectioned buccolingually and examined with the SEM. The results, in MPa, were: 1) 12.55 +/- 5.97; 2) 10.41 +/- 6.16; 3) 9.94 +/- 7.26; 4) 12.25 +/- 4.70; 5) 13.02 +/- 8.01; 6) 16.51 +/- 8.62; 7) 12.51 +/- 8.95; 8) 17.93 +/- 6.44. ANOVA and Student-Newman-Keuls tests showed no statistically significant differences. SEM evaluation showed that the smear layer was removed in all groups exposing primary dentin tubules infiltrated by resin. A resin-reinforced hybrid layer was readily seen in all specimens.

The effect of training on the ability of children to use dental floss

The effect of training on the ability to use dental floss was evaluated in a study involving forty-eight children in the 6.5 to 7.5 age-group. Using a dental plaque index for the proximal surfaces, we observed significantly superior average results for the trained group (five weekly sessions) relative to the group with no training. We also observed a significant average difference favoring the male trained group relative to the female trained group.