Stability and failure rate during 3 years of fixed retention: A follow-up of an randomized clinical trial on adolescents with four different lingual retainers.

OBJECTIVE: To evaluate stability outcomes and failure rates associated with four types of lingual retainers: (1) dead-soft wire, (2) multistrand stainless steel (SS) wire, (3) CAD/CAM nitinol, and (4) connected bonding pads (CBPs) after 3 years of retention. METHODS: This study enrolled 96 patients (66 females, 30 males) with a median age of 19 years with four types of lingual retainers: (1) 0.016 × 0.022-inch dead-soft wire, (2) 0.0215-inch five-strand SS wire, (3) 0.014 × 0.014-inch CAD/CAM nitinol wire, and (4) CBPs. The irregularity index, intercanine distances, and arch lengths were obtained and used to evaluate mandibular stability. Failure rates were also assessed during this study. Data were statistically analysed. RESULTS: Irregularity increased, whereas intercanine width and arch length decreased after 3 years of retention. The greatest irregularity was associated with the CBPs and the least with the CAD/CAM retainers. Changes in stability measurements were significantly higher in the dead-soft wire and CBPs than those in the CAD/CAM nitinol and multistrand SS wires. Parallel to these changes, the frequency of failure yielded similar results with the same significance between the groups. The failure rate of CBPs, in contrast to the CAD/CAM nitinol and multistrand SS wires, was significantly higher in the right quadrant (P < .05). CONCLUSION: After taking the 3-year results into consideration, CAD/CAM nitinol and multistrand SS wires were found to be more successful than the others in maintaining mandibular stability. The most failures were observed with CBPs after 3 years of retention.

Micro-CT evaluation of microleakage under orthodontic ceramic brackets bonded with different bonding techniques and adhesives.

AIM: The aim of this study was to evaluate microleakage under orthodontic ceramic brackets bonded with direct and different indirect bonding techniques and adhesives using micro-computed tomography. MATERIALS AND METHODS: A total of 30 human maxillary premolars were randomly separated into five groups with six teeth in each group. In group I, teeth were bonded directly with Transbond XT (3M Unitek). In group II, group III, group IV, and group V, teeth were bonded through an indirect technique with Custom I.Q. (Reliance Orthodontic Products), Sondhi Rapid-Set (3M Unitek), RMbond (RMO), and Transbond IDB (3M Unitek), respectively, following the manufacturer's instructions. Micro-CT system model 1172 of Skyscan (Kontich, Belgium) was used to scan all samples. NRecon (Skyscan) version 1.6, CT-Analyser V.1.11 (Skyscan), and TView (SkyScan, Bvba) software programs were used for microleakage evaluation. Microleakage values between the test groups were assessed using the Kruskal-Wallis test, while the Wilcoxon signed rank test was used for within-group comparisons. The level of significance was set at P < 0.05. RESULTS: According to the Kruskal-Wallis analysis of variance test, there were no significant differences among the tested groups, with regard to volume and percentage (microleakage/region of interest × 100) of microleakage values (P < 0.05). The Wilcoxon signed rank test showed that coronal microleakage volume and percentage values significantly differed for RMbond and Transbond IDB groups. LIMITATIONS: In the study, only ceramic brackets were used and microleakage into mini gaps did not show up on the micro-CT image because 50% silver nitrate solution could not penetrate into mini gaps which are smaller than silver nitrate particles. CONCLUSION: Use of direct and indirect bonding techniques with different adhesives did not significantly affect the amount of microleakage.

Effects of low-intensity pulsed ultrasound on bone formation after the expansion of the inter-premaxillary suture in rats: a histologic and immunohistochemical study.

BACKGROUND: Orthodontic maxillary expansion is a commonly-performed treatment approach to correct transverse maxillary deficiencies by separating the mid-palatal suture. To obtain a successful treatment result and prevent relapse, the expanded maxillary sutures require maintenance by means of qualified bone reorganisation. AIM: To assess the effects of low-intensity pulsed ultrasound (LIPUS) on sutural bone formation after the expansion of the interpremaxillary suture in rats. METHODS: Sixteen male Wistar rats, 6 to 8-week old, were used. The expansion appliance comprised a helical spring fabricated from 0.014 inch stainless steel wire (Dentaurum, Ispringen, Germany). The rats were divided into two equal groups and randomly assigned to the LIPUS treatment group or a sham-operation group. LIPUS was delivered via a 2.5 cm diameter ultrasound transducer (Exogen, Smith and Nephews, Inc., Memphis, TN, USA) for 20 minutes per day during 7 days of post-expansion retention. Following retention, the rats' maxillae were surgically removed and histologic and immunohistochemical specimens were prepared and examined. RESULTS: The number of osteoblasts and blood vessel dimensions in the ultrasound group increased but was not significant, compared with the control group. A statistically significant difference in osteocalcin, VEGF and TGF-ß immunoreactivities (p < 0.01) was found in the area of the mineralising tissue. Only VEGF immunoreactivity was significant between two groups (p < 0.01) in the fibrous tissue area. CONCLUSIONS: The area of mineralising tissue in the LIPUS-applied group expressed activity markers for osteocalcin, VEGF and TGF-ß compared with a surrounding area of fibrous tissue. Cellular activation in the LIPUS group was greater than that of controls. Therefore, LIPUS may be accepted as a useful approach to enhance sutural bone formation.

The Determination, Monitoring, Molecular Mechanisms and Formation of Biofilm in E. coli.

Biofilms are cell assemblies embedded in an exopolysaccharide matrix formed by microorganisms of a single or many different species. This matrix in which they are embedded protects the bacteria from external influences and antimicrobial effects. The biofilm structure that microorganisms form to protect themselves from harsh environmental conditions and survive is found in nature in many different environments. These environments where biofilm formation occurs have in common that they are in contact with fluids. The gene expression of bacteria in complex biofilm differs from that of bacteria in the planktonic state. The differences in biofilm cell expression are one of the effects of community life. Means of quorum sensing, bacteria can act in coordination with each other. At the same time, while biofilm formation provides many benefits to bacteria, it has positive and negative effects in many different areas. Depending on where they occur, biofilms can cause serious health problems, contamination risks, corrosion, and heat and efficiency losses. However, they can also be used in water treatment plants, bioremediation, and energy production with microbial fuel cells. In this review, the basic steps of biofilm formation and biofilm regulation in the model organism Escherichia coli were discussed. Finally, the methods by which biofilm formation can be detected and monitored were briefly discussed.

The relationship of orthodontic treatment need with periodontal status, dental caries, and sociodemographic factors.

The aim of this study was to determine the relationship of orthodontic malocclusion with periodontal status, dental caries, and sociodemographic status. Our study population consisted of a sample of 836 school children (384 male and 452 female, aged 11-14 years). Four experienced orthodontists and two experienced periodontists performed the clinical examinations. The Treatment Priority Index (TPI), Community Periodontal Index of Treatment Needs (CPITN), decayed, missing, filled teeth (DMFT) scores, and a questionnaire that surveyed socio-demographic status of students were used. Spearman's rank correlation coefficients were used to measure the association between variables. TPI scores showed that 36.4% of the students had normal occlusion, while 41.2% had slight, 15.7% had definite, 4% had severe, and 2.7% had very severe malocclusion. TPI values did not show any significant differences between pupils in different age, gender, socioeconomic status groups, and CPITN scores, whereas there was a significant relationship between TPI and DMFT scores. The orthodontic treatment need was not significantly correlated with CPITN or socio-demographic status; however, the correlation coefficient showed a significant relationship between TPI and DMFT scores.

Orthodontic treatment of a patient with oral-facial-digital syndrome.

Oral-facial-digital syndrome is characterized by heterogeneous clinical features involving malformations of the face, oral cavity, and digits. The syndrome has been reported only in women, suggesting that it is lethal in males. Affected females have malformations of the oral cavity (cleft palate, lip and tongue, abnormal dentition, and hamartomas), face (hypertelorism and milia), and digits (syndactyly, brachydactyly, and polydactyly). In this article, we report the orthodontic treatment of a 21-year-old woman with oral-facial-digital syndrome.

Real-time cell analysis of the cytotoxicity of orthodontic mini-implants on human gingival fibroblasts and mouse osteoblasts.

INTRODUCTION: The aim of this study was to evaluate the cytotoxic effects of orthodontic mini-implants on gingival fibroblasts and osteoblasts. METHODS: The orthodontic mini-implants used in this study were Orthodontic Mini Implant (Leone, Florence, Italy), MTN (MTN, Istanbul, Turkey), AbsoAnchor (Dentos, Daegu, South Korea), IMTEC Ortho (3M Unitek, IMTEC, Ardmore, Okla), VectorTAS (Ormco, Glendora, Calif). The materials were incubated in Dulbecco's modified eagle's culture medium for 72 hours according to ISO 10993-5 standards (surface area-to-volume ratio of the specimen to cell-culture medium, 3 cm(2)/mL). A real-time cell analyzer (xCELLigence, Roche Applied Science, Mannheim, Germany; ACEA Biosciences, San Diego, Calif) was used to evaluate cell survival. After seeding 200 µL of the cell suspensions into the wells of the E-plate 96, gingival fibroblasts were treated with bioactive components released by the metallic materials and monitored every 15 minutes for 190 hours. For the proliferation experiments, the statistical analyses used were 1-way analysis of variance and Tukey-Kramer multiple comparisons tests. RESULTS: There was no significant differences between the human gingival fibroblast cell indexes of the control and study groups (P >0.05). When evaluated at 27 and 96 hours, only the VectorTAS mini-implants showed statistically significant decreases in the M3T3 cell index (P <0.001) compared with the control group. No significant differences were found among the control and all study groups (P >0.05). Furthermore, the Leone and MTN mini-implants showed statistically significant decreases (P <0.001) at 190 hours. Also, the VectorTAS mini-implants demonstrated a significant decline (P <0.05) at the same time in the M3T3 cell index. CONCLUSIONS: These findings provide fundamental knowledge and new insights for future design and development of new biocompatible titanium alloys for orthodontic mini-implants and temporary anchorage devices.

Effects of zoledronic acid on sutural bone formation: a computed tomography study.

The aim of this study was to investigate the effects of systemically applied zoledronic acid (ZA) on osteoblastic bone formation and relapse in the rat sagittal suture after expansion. Eighteen 12-week-old male Wistar rats were divided into three groups. In groups 1 and 2, a saline solution was given subcutaneously after expansion and the retention period lasted for 14 and 7 days, respectively. In group 3, 0.1 mg of ZA was diluted with saline and given subcutaneously after expansion: the retention period lasted for 7 days. Computed tomography (CT) measurements were obtained at the start of the study (T1), after expansion (T2), after the retention period (T3), and after the follow-up period (T4). The amount of expansion and relapse and the density of the newly formed bone in the expansion area were measured. The mean bone density values in hounsfield unit (HU) of the newly formed bone were recorded using MX View Workstation. Data were analysed using the Kruskal-Wallis, Friedman, Wilcoxon, and Mann-Whitney U-tests. The results showed that there were significant differences between the groups in the density of newly formed bone after the retention period (P < 0.05). Statistically significant differences were observed when the relapse percentages were compared between the groups (P < 0.05). ZA stimulated bone formation and decreased the relapse ratio after expansion in the rat sagittal suture.

Effects of bisphosphonates on sutural bone formation and relapse: A histologic and immunohistochemical study.

INTRODUCTION: The aim of this experimental study was to evaluate the effects of systemically applied zoledronic acid on bone regeneration in response to expansion of the sagittal suture and relapse in rats. METHODS: Thirty-six male Wistar rats were divided into 3 groups. In the first and second groups, saline solution was given subcutaneously after expansion, and the retention periods lasted 14 and 7 days, respectively. In the third group, 0.1 mg of zoledronic acid was diluted with saline solution and given subcutaneously after expansion; the retention period lasted for 7 days. Expansion and relapse amounts were measured by using computed tomography. After the retention period, 6 rats from each group were killed for histologic and immunohistochemical assessments. The other 6 rats from each group were used for observation of the relapse. RESULTS: The histologic evaluation showed that, in groups 1 and 2, the numbers of osteoblasts were less than observed in group 3. When scores of staining intensity were compared, immunoreactivities were statistically significantly increased in group 3 compared with groups 2 and 1. Statistically significant differences were found when the relapse percentages were compared between the groups (P <0.05). The smallest relapse occurred in group 3. CONCLUSIONS: Zoledronic acid has positive effects on bone formation in the sagittal suture in response to expansion and decreases the relapse ratio after expansion in rats.

Real-time cell analysis of the cytotoxicity of the components of orthodontic acrylic materials on gingival fibroblasts.

INTRODUCTION: The aim of this study was to evaluate the cytotoxicity of 3 orthodontic acrylic materials and 2 manipulation methods. METHODS: The orthodontic acrylic materials Orthocryl EQ (Dentaurum, Ispringen, Germany), Orthoplast (Vertex Dental, Zeist, The Netherlands), and O-80 (Imicryl, Konya, Turkey) were prepared with 2 polymerization methods (doughing and spray on). Totally, 60 cylinders (5 × 2 mm), fabricated by using a different acrylic and method, were divided into 6 groups. Gingival fibroblasts were isolated from gingival connective tissue of systemically healthy subjects. Materials were incubated in Dulbecco's modified eagle's medium culture medium (Biological Industries, Beit Haemek, Israel) for 72 hours according to ISO 10993-5 standards (surface area to volume ratio of the specimen to cell-culture medium: 3 cm(2)/mL). Gingival fibroblasts were maintained with Dulbecco's modified eagle medium containing 10% fetal bovine serum. A real-time cell analyzer (RT-CES, xCELLigence; Roche Applied Science, Mannheim, Germany, and ACEA Biosciences, San Diego, Calif) was used to evaluate cell survival. After seeding 200 µL of the cell suspensions into the wells (20,000 cells/well) of the E-plate 96, gingival fibroblasts were treated with bioactive components released by the acrylic materials (1/1 and 1/2 dilutions) and monitored every 15 minutes for 121 hours. For the proliferation experiments, the statistical analyses used were 1-way analysis of variance (ANOVA) and Tukey-Kramer multiple comparisons tests. RESULTS: There was no significant difference between the cell indexes of the control and study groups for the 1/1 and 1/2 dilutions at 21 and 32 hours. When evaluated at 68 hours, all 1/2 dilutions of acrylic materials showed statistically insignificant differences (P >0.05) except for Orthoplast (P <0.05). But all acrylic materials were different from the control group in the 1/1 dilutions (P <0.001). At 121 hours, all test groups were significantly different from the untreated control group (P <0.001). CONCLUSIONS: The results indicate that the long cycle increased the cytotoxicity of the tested materials, and there was no significant difference between the spray-on and doughing methods on cytotoxicity.

The short-term effects of manual and interactive powered toothbrushes on the periodontal status of orthodontic patients: A randomized clinical trial.

OBJECTIVE: To compare the effects of manual and interactive powered toothbrushes on periodontal status of patients during fixed orthodontic treatment. MATERIALS AND METHODS: Thirty-six patients aged 12 to 18 years were included in this parallel design randomized clinical trial. Patients were randomly divided into two groups: manual toothbrushes (MT group) and interactive powered toothbrushes (PT group). The plaque index (PI), gingival index (GI), and bleeding on probing (BOP) scores were obtained before brushing (T0), 4 weeks (T1), 2 months (T2), and 4 months (T3) after brushing initiation. Periodontal measurements were performed by the same researcher that blinded to the groups' randomization. Data were analyzed with Mann-Whitney U and Friedman tests for the comparison of parameters between groups and times. RESULTS: Significant differences were found in PI values at all time intervals (P < 0.001), with one exception (T2-T3 in the MT group). The GI changes between timepoints were parallel to the BOP findings of the PT group. Both groups had significantly lower bleeding scores in both T0-T2 and T0-T3 time intervals (P < 0.001). There was a significant reduction in the bleeding score of PT group between T1-T3 time interval (P < 0.05); however, there were no significant differences between the groups at any timepoint. PI and GI scores were statistically decreased in the PT group compared with the MT group from baseline to 4 months (P < 0.05). CONCLUSION: All periodontal parameters decreased during the 4-month study period. The interactive powered toothbrushes may be an alternative to manual toothbrushes in terms of maintenance of periodontal health during fixed orthodontic treatment.

Effects of different lingual retainers on periodontal health and stability.

OBJECTIVES: To evaluate the effects of different lingual retainers on periodontal health and stability of mandibular anterior teeth at the 1-year follow-up. MATERIALS AND METHODS: One hundred thirty-two patients were randomly allocated to four groups using different lingual retainers: group 1, 0.016 × 0.022-in dead-soft wire; group 2, 0.0215-in 5-strand stainless steel wire; group 3, 0.014 × 0.014-in computer-aided design/computer-aided manufacturing nitinol retainer (Memotain); group 4, connected bonding pads. Plaque, gingival, and calculus indexes were used to evaluate periodontal health, and Little's irregularity index, intercanine width, and arch length measurements were performed to evaluate stability. All measurements were performed at each time point (debonding and 3, 6, 9, and 12 months). RESULTS: The mean value of the gingival index obtained in group 3 was lower than the mean value for all other groups. The mean value of the calculus index was the lowest in group 3, and there was a significant difference between group 3 and groups 1 and 2. No differences were found among the groups in terms of plaque index, intercanine width, and arch length. The least irregularity was obtained in groups 2 and 3. There were no significant differences between these groups and groups 1 and 4. CONCLUSIONS: Gingival inflammation and calculus accumulation were the lowest in group 3 (Memotain). The irregularity for Memotain and stainless steel retainers was less than or the other groups. However, no clinically significant worsening of periodontal health or relapse were seen in any groups after 1 year.

Identical unerupted maxillary incisors in monozygotic twins.

Mesiodens is the most common type of supernumerary tooth found in the premaxilla. It might be discovered by the orthodontist by chance on a radiograph or as the cause of an unerupted maxillary central incisor. The genetic transmission of supernumerary and impacted teeth is poorly understood. The occurrence of identical unerupted maxillary central incisors and mesiodentes in monozygotic twins suggests that genetic factors might influence the etiology of this problem. In this case report, we discuss the treatment of unerupted maxillary permanent incisors caused by mesiodentes in monozygotic twins.

Does rapid maxillary expansion affect the eruption of upper third molars?

OBJECTIVE: To test the hypothesis that there is no difference in the movement of the upper third molars between rapid maxillary expansion (RME) and non-RME patients. MATERIALS AND METHODS: This study was performed on 30 patients divided into two groups. The study group included 20 patients who had maxillary narrowness and bilateral maxillary third molars and who had undergone RME application. The control group of 10 patients had a bilateral crossbite, had bilateral maxillary third molars, and did not receive orthodontic treatment. The records included lateral and frontal cephalometric films and maxillary plaster models. In the study group, records were taken before expansion (T1), after expansion (T2), and at the retention period (T3). T2 records were not taken in the control group because this period was too short to observe any changes. Friedman tests were used to observe within groups, and the Mann-Whitney U-test was used to see the differences between groups on films and casts. RESULTS: Frontal films showed that vertical eruption occurred after the retention period in the RME cases. Cephalometric films revealed that the angular eruption occurred immediately after expansion. However, the results were not significant with respect to the control group. CONCLUSION: The hypothesis was rejected. Rapid maxillary expansion affects maxillary third molar movement during and after the RME procedure. RME may indicate upper third molar eruption, but the final position of third molar was not different compared to the normal growth pattern.

Effects of contemporary orthodontic composites on tooth color following short-term fixed orthodontic treatment: a controlled clinical study.

BACKGROUND/AIM: To determine the color alterations of natural teeth associated with different orthodontic composites used in comprehensive short-term treatment. MATERIALS AND METHODS: Twenty-two patients were treated with fixed appliances and 22 untreated subjects were also evaluated. Lower incisors were bonded with different orthodontic composites: 42 with Grengloo, 41 with Light Bond, 31 with Kurasper F, and 32 with Transbond XT. The color parameters of the Commission Internationale de l'Eclairage (CIE) were measured for each tooth with a spectrophotometer. Color assessment in relation to time, adhesive material, and their interaction was made with 2-way mixed analysis of variance (ANOVA) and 1-way ANOVA for the color differences (ΔE*). Further analyses were done using Tukey's honestly significant difference tests and paired-samples t-tests. RESULTS: The color of teeth was affected by treatment. The mean L* and a* values increased, whereas the mean b* values decreased. Total color differences of teeth demonstrated visible color changes clinically after treatment, ranging from 1.12 to 3.34 ΔE units. However, there were no significant differences for color of enamel. CONCLUSION: Teeth may be discolored with fixed appliances during treatment. Moreover, contemporary orthodontic composites have similar effects of enamel discoloration.

Evaluation of salivary total oxidant-antioxidant status and DNA damage of children undergoing fixed orthodontic therapy.

OBJECTIVE: To determine the total oxidant status (TOS), total antioxidant status (TAS), and the 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels and their interrelationship in the saliva of children undergoing fixed orthodontic therapy. MATERIALS AND METHODS: Thirty children were randomly divided into three groups. The attachments were bonded to all of the teeth using three different orthodontic composites: Transbond XT, Kurasper F, and GrenGloo. The salivary levels of TOS, TAS, and 8-OHdG were determined three times, as follows: before treatment (T1) and at 1 month (T2) and 3 months (T3) following appliance placement. All data were statistically analyzed. RESULTS: There were no significant differences in TOS, TAS, and 8-OHdG within the same time periods among the three different orthodontic composites (P > .05). TAS in all composite groups decreased over time. These decreases were found to be significant for Kurasper F and GrenGloo at the T1-T3 and T2-T3 time periods (P < .05). In all composite groups 8-OHdG decreased between T1 and T2 (P < .05). However, 8-OHdG in all composite groups increased from T2 to T3. These differences in 8-OHdG were significant in Kurasper F and GrenGloo (P < .05). CONCLUSIONS: Fixed orthodontic appliances bonded with the tested composites did not increase the cytotoxicity markers in saliva.

A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models.

OBJECTIVE: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. METHODS: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. RESULTS: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. CONCLUSIONS: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

Antibacterial and mechanical properties of propolis added to glass ionomer cement.

OBJECTIVE: To investigate whether adding ethanolic extracts of propolis (EEP) might influence the antibacterial and mechanical (shear-peel band strength [SPBS]) properties of conventional glass ionomer cement (GIC) used in orthodontic band cementation. MATERIALS AND METHODS: The cement was divided into four groups: one using the original composition and three with 10%, 25%, and 50% EEP added to the liquid and then manipulated. An antimicrobial assay, broth-dilution method was used to determine the antibacterial capacity of the GIC containing EEP. Eighty teeth were used for the mechanical assay, and an Instron testing machine was used to evaluate the SPBS. Kolmogorov-Smirnov and Kruskal-Wallis tests were used for statistical analyses. RESULTS: GIC with the addition of 25% and 50% EEP activated inhibition of Streptococcus mutans (ATCC 25175) growth, but this effect did not occur in the group to which 10% EEP was added or in the control GIC group. There was no significant difference between the groups in terms of SPBS (P > .05). CONCLUSIONS: The addition of EEP may increase antibacterial properties without negatively modifying the mechanical properties of conventional GIC.

Evaluation of the genotoxicity and cytotoxicity in the buccal epithelial cells of patients undergoing orthodontic treatment with three light-cured bonding composites by using micronucleus testing.

OBJECTIVE: This study evaluated the cytotoxicity and genotoxicity of fixed orthodontic treatment with three different light-cured orthodontic bonding composites by analyzing micronucleus (MN) formation in the buccal mucosa during a 6-month period. METHODS: Thirty healthy volunteers were selected from consecutive patients referred for orthodontic treatment. Equilibrium 2 brackets and molar tubes (Dentaurum) were bonded with three different light-cured orthodontic bonding composites-Transbond XT (3M Unitek), Kurasper F (Kuraray Europe), or GrenGloo (Ormco Corporation)- to all teeth in both arches. Exfoliated buccal epithelial cells were scraped from the middle part of the inner cheeks with sterile cement spatulas before treatment and at 1, 3, and 6 months after treatment. MNs and nuclear alterations, such as karyorrhexis (KR), karyolysis (KL), and binucleated cells (BNs), were scored under a light microscope. Repeated measure ANOVA was used to calculate statistical differences in degenerative nuclear abnormalities. RESULTS: MN rates did not significantly differ among different time points within the same cell type (p > 0.05). In contrast, the number of BNs in buccal epithelial cells significantly increased in all composite groups (p < 0.01, Transbond XT; p < 0.001, Kurasper F and GrenGloo). KL frequency significantly increased between the beginning and end of the study in the Kurasfer F (0.80 ± 0.79 to 1.90 ± 1.10; p < 0.05) and GrenGloo (1.30 ± 1.06 to 2.40 ± 1.08; p < 0.05) groups. CONCLUSIONS: After 6 months of fixed orthodontic treatment with different light-cured composites, morphological signs of cytotoxicity were observed but genotoxic effects were absent.

Level of residual monomer released from orthodontic acrylic materials.

OBJECTIVE: To quantify, with high-pressure liquid chromatography (HPLC), the amount of residual monomer leached from different orthodontic acrylic materials prepared with two different manipulation methods. MATERIALS AND METHODS: Eighty cylindrical specimens (5 × 25 mm) were divided into eight groups (n  =  10). The specimens were prepared with four acrylic materials-Orthocryl Neon Blue (Dentaurum), Orthocryl EQ (Dentaurum), Orthoplast (Vertex), and O-80 (Imicryl)-and with two different manipulation methods: doughing and spray-on. HPLC measurements were made at intervals of 2 hours, 6 hours, 1 day, 1 week, and 3 months. One-way analysis of variance (ANOVA) and Tukey's honestly significant difference multiple-comparison test were used to assess the amount of monomer eluted from the various groups. To assess the differences within each group over the various periods, repeated-measures ANOVA and paired t-tests were used. RESULTS: Statistically significant differences were found within the groups in the amount of residual monomer in the specimens at different time intervals (P < .001). HPLC showed statistically significant differences among the groups (P < .05) in the amount of eluted monomer. Evaluation of the manipulation techniques showed that the monomer release rate was higher in the specimens prepared with the doughing method. When the four acrylic materials were compared, the specimens made from Orthoplast (Vertex) showed the highest rate of monomer release with both manipulation techniques. CONCLUSION: The spray-on method can be recommended to clinicians for the preparation of orthodontic appliances.