Histological Evaluation of Single and Double-visit Direct Pulp Capping with Different Materials on Sound Human Premolars: A Randomized Controlled Clinical Trial.

INTRODUCTION: The aim of this study was to evaluate the clinical and histological status of the pulp in sound human premolars after direct pulp capping (DPC) with four different DPC methods/materials. METHODS AND MATERIALS: This study was conducted on eight volunteers who had to extract four first premolars due to orthodontic treatment. Subsequent to tooth isolation, standardized class I occlusal cavities were prepared and the buccal pulp horns were exposed. Then four different protocols of DPC were applied randomly: group A (control); calcium hydroxide lining paste (Dycal), group B; ProRoot MTA (standard double-visit method), group C; ProRoot MTA (single-visit method) and group D; calcium hydroxide injectable paste (Multi-Cal). The cavities were then restored and the patients were put on a six-week clinical follow-up and by the end of this period the teeth were extracted for histological evaluation. Data were analyzed with the Kruskal Wallis test and the level of significance was set at 0.05. RESULTS: In terms of clinical symptoms and formation of hard tissue bridge (HTB), no significant differences were found between groups A, B and C (P>0.05); however, group D's results were significantly different as they exhibited minimal HTB formation and excessive sensitivity (P<0.05). Inflammation was significantly lower in group B (P>0.05). CONCLUSION: Application of MTA during a single-visit protocol of DPC was clinically and histologically as successful as the standard double-visit method but the routine use of Multi-Cal as pulp capping material is questionable and should be reconsidered.

The effect of recommending a CPP-ACPF product on salivary and plaque pH levels in orthodontic patients: a randomized cross-over clinical trial.

OBJECTIVE: Along with their re-mineralizing capacity, calcium phosphopeptide-amorphous calcium phosphate products combined with fluoride (CPP-ACPF) could also be beneficial by neutralizing acidic salivary and plaque pH. The purpose was to evaluate the effect of CPP-ACPF on salivary and plaque pH in orthodontic patients. MATERIALS AND METHODS: As a triple-blind, cross-over randomized trial, 30 orthodontic patients with fixed appliances (age range = 15.70 ± 4.08 years) were recruited and randomly assigned to two groups. A CPP-ACPF paste (MI Paste Plus, GC America, Alsip, IL) was used by group 1 (n = 15) and a placebo by group 2 (n = 15) for 1 month. After a 1 month washout period, patients used the alternative paste for another month. Plaque and salivary pH levels were measured at all before and after periods. RESULTS: By applying MI Paste Plus, the plaque pH increased from 5.81 ± 0.45 to 6.60 ± 0.38 (p < 0.05), whereas the before and after salivary pH recordings, which were 6.72 ± 0.43 and 6.71 ± 0.38, respectively, remained statistically unchanged (p > 0.05). CONCLUSION: MI Paste Plus can be clinically beneficial in increasing plaque pH levels, but has no effect on the salivary pH.

Measuring the reliability of sagittal facial anthropometric measurements under soft tissue displacement using a modified ruler.

OBJECTIVE: Despite the current use of radiography for quantifying sagittal skeletal measurements, it is an unsuitable way for screening or epidemiologic purposes. Although not fully approved, anthropometric measurements have been suggested as a substitute, and considering displacement of soft tissues, could possibly lead to more consistent results. The purpose of this study was to evaluate the reliability of anthropometric anteroposterior facial measurements under soft tissue compression using a special ruler. MATERIAL AND METHODS: Anthropometric measurements were done with a specifically designed sliding ruler twice on 36 adult patients with a 14 day lag between two measurements. The ruler measured the distance between the external acoustic meatus and the nasion (Na), subnasal (Sn) point and the soft tissue pogonion (Pog). The soft tissue was displaced during measurements only to the extent that the underlying hard tissue resistance was felt subjectively by each assessor. The intraclass correlation coefficient (ICC) was calculated for both inter- and intra- rater measurements using SPSS software. RESULTS: All measurements had inter- and intrarater agreements above 0.9, with only a few parameters having lower bound confidence intervals below 0.9, but more than 0.8. CONCLUSION: Sagittal facial anthropometric measurements under soft tissue displacement using the specific ruler are valid and reliable and could possibly aid orthodontists in chairside craniofacial assessments.

Investigating the effect of incorporating nanosilver/nanohydroxyapatite particles on the shear bond strength of orthodontic adhesives.

INTRODUCTION: Development of clinically acceptable orthodontic adhesives with additional anti-microbial and remineralizing features could be undertaken only if their mechanical properties have also been considered. The purpose of this study was to investigate the effect of incorporating Silver and Hydroxyapatite (HA) nanoparticles on the shear bond strength (SBS) of an orthodontic adhesive. METHODS: Silver and HA nanoparticles were prepared and inspected by scanning electron microscopy and EDAX analysis. The nanoparticles were added to the primer of Transbond XT in 1%, 5% and 10% silver concentrations. Each compound (along with a control) was used for bonding stainless steel brackets to 12 human premolars (48 in total) and the SBS of all samples, along with their ARI scores were measured. RESULTS: The SBS of the control, 1%, 5% and 10% nanoparticle groups were 12.06 ± 5.48, 20.66 ± 5.72, 10.77 ± 8.16 and 5.40 ± 2.00 MPa, respectively. A significant difference existed between all study groups (p < 0.05), except for the control-5% and 5%-10% study groups (p = 0.99 and p = 0.35). There was no statistically significant difference in distribution of ARI scores across the study groups (p = 0.44). CONCLUSIONS: Incorporation of silver/HA nanoparticles containing 5% and 1% silver maintains and increases the SBS of orthodontic adhesives, respectively, whereas increasing the amount of particles to 10% has an undesirable effect when compared to the control group.

Comparison of wire loop and shear blade as the 2 most common methods for testing orthodontic shear bond strength.

INTRODUCTION: The purpose of this study was to compare 2 common methods of measuring orthodontic shear bond strength. METHODS: Brackets were bonded to 40 bovine incisors, and the teeth were mounted in a jig. The teeth were paired for symmetry, and the pairs were divided into 2 groups for debonding. In group 1, the shear force was applied with a rectangular wire under the tie wings. In group 2, a shearing blade applied force to the junction between the bracket base and the adhesive. RESULTS: Debonding with the shear blade produced higher (24.86 +/- 7.44 MPa) and more dispersed (coefficient of variation = 29.91%) bond strengths compared with the wire loop (17.12 +/- 3.16 MPa, coefficient of variation = 18.44%). Adhesive remnant index (ARI) scores showed a tendency for cohesive failure in the enamel in the shear-blade group (ARI = 5) compared with adhesive failure (ARI = 3) in the wire group. CONCLUSIONS: There is a need to standardize bond strength tests. The results of this study favor the wire-loop method, which might have more similarity to clinical loads. The regression formula might make comparison of previous studies easier.