Evaluation of the epithelial cells of lower lip mucosa after debonding of fixed orthodontic appliances.

BACKGROUND: Orthodontic appliances (ligatures, braces, wires, etc.), are one of the main sources of trauma in the oral cavity. Friction between brackets and mucosa is a kind of chronic trauma that may cause buccal mucosal proliferation and ulceration and is one of the most common complaints of patients during orthodontic treatment. The aim of this study was to evaluate the changes of the lower lip epithelial cells after the removal of orthodontic fixed appliances. METHODS: Cells of lower lip oral mucosa of 31 orthodontic patients were collected by exfoliative cytology in three times: immediately (T0), 30(T1) and 60 (T2) days after debonding. Nuclear (NA) and cytoplasmic (CA) areas, NA/CA ratio, cell morphology and cellularity of smears were evaluated using cytomorphometric and cytomorphologic methods. Friedman test followed by the Wilcoxon test was used to compare the NA, CA and NA/CA values in three different times. Cell morphology and cellularity were analyzed by the Chi-square test. All statistical tests were performed with SPSS version 20. RESULTS: The NA and CA values increased significantly (P<0.001) after the removal of friction and irritation of orthodontic appliances in T1 and T2 and reached their highest level in T2. The NA/CA values did not change significantly (P=0.25). Class I smears, according to Papanicolaou classification, were observed in T0, T1, and T2. Superficial epithelial cells were predominant cell types in the lower incisor region in all times without statistically significant difference in three intervals. CONCLUSIONS: Orthodontic appliances increase keratinization of lip mucosa which is considered an adaptive reaction to the mechanical stimulus, but after removing of the appliances cellular activity rapidly increases. Keratinization is the main change observed at the end of orthodontic treatment.

Sealing efficacy of mineral trioxide aggregate with and without nanosilver for root end filling: An in vitro bacterial leakage study.

BACKGROUND: Various materials have been added to mineral trioxide aggregate to enhance its properties. This study was aimed to compare the sealing efficacy of MTA with and without nanosilver using bacterial leakage approach. MATERIAL AND METHODS: Seventy canine teeth were prepared and obturated. Then, after apical resection, the root-end cavities were prepared by ultrasonic retrotips. Teeth were randomly divided into 4 groups containing two experimental groups (n=30) and two negative and positive controls (n=5). In group 1 and 2, root-end cavities were respectively filled with MTA and MTA with nanosilver (by 1% weight). Leakage assessment was carried out by bacterial leakage apparatus with Enterococcus faecalis species. Leakage comparison between experimental groups was done using Mann-Whitney test by Spss 16 software at significancy level of 0.05. RESULTS: The median bacterial leakages for MTA and MTA with nanosilver were 19 and 2, respectively. The mean bacterial leakages for MTA and MTA with nanosilver were 30.06±28.67 and 9.66±14.25, respectively. Mann-Whitney test indicated that there was a significant difference in bacterial leakage day between two experimental groups (P=0.002). CONCLUSIONS: Based on the findings of this in-vitro bacterial leakage study, adding nanosilver to MTA decreased its sealing ability. Key words:Root canal therapy, root canal obturation, root canal filling materials, nanosilver, MTA.

Arch width changes in patients with Class II division 1 malocclusion treated with maxillary first premolar extraction and non-extraction method.

BACKGROUND: The aim of this study was to determine arch width changes during maxillary first premolars extraction and non-extraction treatment in patients with Class II division 1 malocclusion. MATERIAL AND METHODS: Dental casts of 91 Class II division 1 patients (36 males and 55 females) were evaluated. The minimum age of the subjects at the beginning of treatment was above 16 years. 48 patients were treated with extraction of the maxillary first premolars and 43 patients were treated without extraction. Pre- and post-treatment maxillary and mandibular inter-canine and inter-molar arch widths were measured. RESULTS: At the end of treatment, maxillary and mandibular inter-canine widths of both groups increased significantly. The maxillary inter-molar width decreased in the extraction group and increased in the non-extraction group. The mandibular inter-molar width increased significantly in both groups. No significant differences were observed between males and females. CONCLUSIONS: The results of this study indicated that there was a tendency for an increase in arch width during both the extraction and non-extraction treatment except maxillary inter-molar width in the extraction cases. Key words:Dental arch, malocclusion, angle Class II, tooth movement, extraction.

Assessment of Factors Affecting Adolescent Patients' Compliance with Hawley and Vacuum Formed Retainers.

INTRODUCTION: Success of orthodontic retention with removable retainers almost entirely depends on patients' compliance. AIM: This study was carried out to investigate the relationship between adolescent orthodontic patients' compliance and various clinical and social factors. MATERIALS AND METHODS: The data were collected from 77 orthodontic patients aged 7-11 years old who had finished the full fixed appliance therapy. Hawley's retainers were used in 34 patients and 43 patients used Vacuum Formed Retainers (VFRs). The subjects completed a questionnaire including several identifiers allowing the respondents to be classified into subgroups. They were also asked to indicate how long they wore their retainers during the day, by writing the number of hours in the report-card for the next three months. Comparison of the results was performed by one-way ANOVA and independent sample-t tests. RESULTS: No significant differences were found between males and females. Type of the retainer, patients' grade of study, mothers' occupation, clinicians' and parents' attitudes and filling the report cards had significant effect on mean wear hours per day. When compliance of the patients was assessed according to treatment location, Living place, parents' educational degrees and ethnicity, no significant differences could be found. CONCLUSION: The adolescent patients' compliance was greater with VFRs than with Hawley's retainers. Parental attitude and doctor-patient relationship had a great impact on adolescent patients' compliance.

Shear bond strength and debonding characteristics of metal and ceramic brackets bonded with conventional acid-etch and self-etch primer systems: An in-vivo study.

BACKGROUND: Different in-vitro studies have reported various results regarding shear bond strength (SBS) of orthodontic brackets when SEP technique is compared to conventional system. This in-vivo study was designed to compare the effect of conventional acid-etching and self-etching primer adhesive (SEP) systems on SBS and debonding characteristics of metal and ceramic orthodontic brackets. MATERIAL AND METHODS: 120 intact first maxillary and mandibular premolars of 30 orthodontic patients were selected and bonded with metal and ceramic brackets using conventional acid-etch or self-etch primer system. The bonded brackets were incorporated into the wire during the study period to simulate the real orthodontic treatment condition. The teeth were extracted and debonded after 30 days. The SBS, debonding characteristics and adhesive remnant indices (ARI) were determined in all groups. RESULTS: The mean SBS of metal brackets was 10.63±1.42 MPa in conventional and 9.38±1.53 MPa in SEP system, (P=0.004). No statistically significant difference was noted between conventional and SEP systems in ceramic brackets. The frequency of 1, 2 and 3 ARI scores and debonding within the adhesive were the most common among all groups. No statistically significant difference was observed regarding ARI or failure mode of debonded specimens in different brackets or bonding systems. CONCLUSIONS: The SBS of metal brackets bonded using conventional system was significantly higher than SEP system, although the SBS of SEP system was clinically acceptable. No significant difference was found between conventional and SEP systems used with ceramic brackets. Total SBS of metal brackets was significantly higher than ceramic brackets. Due to adequate SBS of SEP system in bonding the metal brackets, it can be used as an alternative for conventional system. KEY WORDS: Shear bond strength, Orthodontic brackets, Adhesive remnant index, self-etch.