Ca(OH)2 application modes: in vitro alkalinity and clinical effect on bacteria.

AIM: To compare five calcium hydroxide (CH) products, CH-gutta-percha Plus points(®) (CHGP) and conventional CH paste, for their ability to maintain alkalinity and to assess the clinical antimicrobial effect of CHGP. METHODOLOGY: Calcium hydroxide products were tested in the presence of standardized dentine powder or by titrating them with 1 mol HCl, expressed in mL (±SD). In a clinical trial, 21 single-rooted teeth with primary apical periodontitis were medicated with CHGP or with conventional CH paste. Bacterial samples were taken before and after chemo-mechanical preparation, after dressing and after leaving canals empty but sealed. To compare groups, anova with Tukey's test was used in the laboratory study and Fisher's exact test in the clinical study. Significance level was set at 5%. RESULTS: Pure CH with water (8.5 ± 0.1) and Calasept (9.3 ± 0.1) maintained the highest alkalinity, followed by the gel-like products DS CaOH gel (7.3 ± 0.3) and Ultracal XS (6.8 ± 0.2) and then Biokalkki (6.3 ± 0.3) and Calxyl blue (5.1 ± 0.2). All CH paste products had higher values compared with CHGP (1.6 ± 0.1) (P < 0.05). Saturated solutions of the products were all neutralized to pH 8.6 within 24 h by dentine powder addition. Clinically, culture-negative results were obtained in 5/10 canals in the CHGP group and 7/11 with conventional CH (P > 0.05). CONCLUSIONS: Aqueous CH mixtures kept high pH better than viscous gel products or CHGP. Dentine powder had equal buffering effect on each product tested. CHGP and traditional CH paste both had an antimicrobial effect in the clinical setting, but there was no significant difference between the groups.

A 13-year follow-up of a comprehensive program of fissure sealing and resealing in Varkaus, Finland.

The objective of the study was to examine the coverage of the sealing program on first permanent molars (FPMs) and second permanent molars (SPMs) and first and second premolars (FSPMs), as well as to monitor the fate of the sealed teeth over time. All patients born in 1977 who had had regular check-ups in the Varkaus Health Center, Finland (n = 166) were included in the 1996 study. Data on the annual state of each tooth had been collected retrospectively since 1983. The coverage for the sealant program was 95%, 92%, and 6% of the FPMs, SPMs, and FSPMs, respectively. Out of the FPMs sealed at age 6 years, 28% were subjected to resealing, 13% developed occlusal, and 15% proximal caries during a 13-year follow-up period. From the SPMs sealed at age 11 years, 24% were subjected to resealing, 4% developed occlusal caries, and less than 2% proximal caries during the 9-year follow-up. None of the sealed FSPMs and only 1% of the non-sealed ones developed occlusal caries during the 9-year period. The mean DMF in the study population (n = 160) at age 12 years was 0.8 (n = 124), compared to a nation-wide mean value of 1.2. A large percentage of the FPMs and SPMs were sealed and then resealed during the study period. Although the study design lacked a control group for comparison, the lower caries rates of this study compared to the results of other studies with only a single application of sealants suggest a major role for resealing.

Can Glass ionomer sealants be cost-effective?

Glass ionomer (GI), applied as a pit and fissure sealant, has been shown to be a promising method for caries prevention. It has also been suggested that when GI is used as a sealant material, it can prevent caries, even if partly or totally lost. As there is no need for resealing GI, it may be more cost-effective when compared to a resin-based (RB) sealant. This study evaluated the factors influencing the time needed to apply a sealant as a factor in determining the possible costs of the effectiveness of RB compared to GI sealants. To study this, children born between 1980 and 1983, who had their appropriate second molars sealed between 1993 and 1997, were assessed. The study was then based on a random sub-sample of this group, comprising 140 teeth: 86 sealed with RB (Delton) and 54 with GI (Fuji III). For a hygienist working alone, the whole procedure of applying a sealant, beginning with the cleaning of the tooth and ending with the finished sealant, took, on average, 344 (+/- 59) seconds with RB, and 599 seconds (+/- 89) with GI. This difference in time was found to be statistically significant at p < 0.01. No statistically significant difference existed in the mean time required to apply a sealant between the left (410 +/- 140 seconds) and the right (448 +/- 149 seconds) sides; however, the mandibular teeth required longer for application of the sealant than did the maxillary teeth (447 +/- 161 seconds vs. 408 +/- 125 seconds, respectively; p < 0.01). It was also found that a dentist, working with chairside assistance, took 20% less time to apply either sealant material than did the hygienist working alone. It was concluded that GI sealants, whether resealed or not, cannot be as cost-effective as RB sealants, when the expense of placement in time (and thus costs) is used as the basis of efficacy.

Occlusal restorative decisions based on visual inspection--calibration and comparison of different methods.

The purpose of this in vitro study was to calibrate occlusal restorative decision-making based on visual inspection (VI), and to compare it with visual inspection with magnifying (x1.25) lenses (VIM), and fibre-optic transillumination (VIF). Sixty extracted human third molars mounted in plaster were examined using VI by ten dentists three times during the calibration process. After wash-out periods, the teeth were re-examined by the same dentists using VI, VIM and VIF. The inter-examiner reproducibility for VI, expressed as Kappa (kappa) statistics (kappa +/- SD), was 0.46 +/- 0.10 before and 0.59 +/- 0.11 after the calibration process and remained at the same level after the wash-out period. Intra-examiner reproducibility was substantially higher for VI (kappa -0.68 +/- 0.15) before and after the wash-out period. There were no significant changes in restorative treatment decisions based on VIM and VIF when compared to VI. The reproducibility between the methods was good for VI vs. VIM (kappa = 0.64) and moderate for VI vs. VIF (kappa = 0.56). In contrast, the inter-examiner reproducibilities expressed as Kappa were considerably lower for VIM (kappa = 0.46 +/- 0.17) and VIF (K = 0.42 +/- 0.19). It was concluded that the inter-examiner reproducibility can be improved with a calibration process based on a simple feedback method and that inter-examiner variation, especially without calibration, may be as important a factor for restorative treatment decisions as the diagnostic method itself.

SEM observations on stress corrosion cracking of commercially pure titanium in a topical fluoride solution.

UNLABELLED: OBJECTIVES. The purpose of the present study was to determine whether commercially pure titanium is susceptible to stress corrosion cracking/hydrogen embrittlement in a topical fluoride solution used in preventive dentistry. METHODS: Thin electropolished titanium test specimens were previously cold-rolled or cold-rolled and annealed before testing. For the stress corrosion tests, the U-shaped specimens of both treatment types were stressed into a radius of curvature of 30 mm. Then, the bent part was placed in the fluoride solution at 37 degrees C for 1, 5, 10, and 20 d. The effects of the fluoride solution on cold-rolled and annealed titanium were studied using a scanning electron microscope. In addition, mechanically fractured surfaces of cold-rolled titanium specimens exposed and not exposed to the fluoride solution were examined by SEM. A qualitative evaluation of the surfaces was conducted. RESULTS: Narrow cracks were observed in cold-rolled specimens following exposure to the fluoride solution for 5 d. The cracks were associated with branching, a characteristic of stress corrosion cracking. The cold-rolled specimen exposed to the fluoride solution exhibited a brittle fracture. In contrast, the fracture mode of the unexposed specimen was ductile in nature. SIGNIFICANCE: Topical fluoride solutions can cause stress corrosion cracking of commercially pure titanium.