Effects of laser irradiation at different wavelengths (660, 810, 980, and 1064 nm) on transient receptor potential melastatin channels in an animal model of wound healing.

The aim of the present study was to compare the effectiveness of four different laser wavelengths used for low-level laser therapy(LLLT) on healing of mucositis in an animal model of wound healing, by investigating expression of transient receptor potential melastatin(TRPM) ion channels. Forty-five rats were intraperitoneally injected with 100 mg/kg 5-fluorouracil on day 1 and 65 mg/kg on day 3. Superficial scratching on left cheek pouch mucosa was performed on days 3 and 5. After ulcerative mucositis was clinically detected, LLLT was started (660 nm, HELBO; 810 nm, Fotona-XD; 980 nm, ARC-Fox; and 1064 nm, Fidelis-Plus3) at 8 J/cm(2)/day from days 1 to 4. Oval excisional biopsy was performed at the wound site, and expression of TRPM2 to TRPM8 was evaluated. Student's t test was used for evaluation of significance of TRPM gene expression according to "0" value (α = 0.05). In 980-nm group, TRPM4, TRPM6, and TRPM7 were significantly higher than in the control group (p < 0.005). In 660, 810, and 1064 nm groups, only TRPM6 was significantly higher than in control group (p < 0.005). There were no significant differences between control and sham groups (p > 0.05). These findings suggest that expression of TRPM6 gene was significantly affected by irradiation with lasers at different wavelengths, whereas the TRPM4 and TRPM7 genes were only expressed in the 980-nm diode laser group. TRPM6 gene was highly expressed during LLLT, which may lead to accelerated wound healing and tissue repair. In contrast, there was some evidence that the 980-nm diode laser caused increased expression of TRPM4, TRPM6, and TRPM7 which are responsible for stimulation of Ca(2+) and Mg(2+) metabolism, as well as apoptotic pathways of controlled cell death.

Evaluation of the effects of different surface configurations on stability of miniscrews.

INTRODUCTION: The aim of this study was to analyze the effects of screw design and force application on the stability of miniscrews, using RTT, SEM, and histomorphometric analyses. MATERIALS AND METHODS: Eighty cylindrical, self-drilling, and Ti6Al4V alloy miniscrews (1,6 × 6 mm) were used. Four mini-screws were inserted in fibulas of each rabbit, and 115 G of force was immediately applied. Four miniscrews were inserted in the other fibula, on which no force was applied. Eight weeks after insertion, osseointegration between miniscrew and the surrounding bone was evaluated by the histomorphometric analyses, SEM, and RTT. Kruskal-Wallis and the paired t-tests were used for statistical analysis. RESULTS: Values obtained from Group I were significantly higher than those of the other loaded groups (P < .05). There were no differences in RTT scores among Groups II, III, and IV. Similar findings were also observed for unloaded mini-screws. There was no significant difference between Groups I and I(C), while the differences between loaded and unloaded controls for each miniscrew were statistically significant. CONCLUSIONS: Immediate loading of miniscrews does not impair screw stability. Also, the diameter of miniscrew and more frequent thread pitches have a positive effect on stability; however, length of miniscrews does not have a significant effect on the stability.

Effects of impacted maxillary canines on root resorption of lateral incisors : A cone beam computed tomography study.

OBJECTIVES: The aim of this study was to analyze the amount of root resorption of maxillary lateral incisors by relating the position, location, and angulation of the impacted canine using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: The study sample consisted of panoramic and CBCT radiographs of 46 patients with a unilateral impacted canine (16 males and 30 females; mean age: 19.53 ± 6.66 and 19.44 ± 5.77 years, respectively). Sector location and canine angulation were measured in panoramics. All tomographs were obtained using CBCT (NewTom 5G, QR, Verona, Italy) and three-dimensional (3D) reconstructions of the maxillary laterals assessed by Mimics 14.01 image analysis software. RESULTS: Upper lateral incisor volume was smaller on the impacted side (401.95 ± 83.69 mm3) than on the nonimpacted side (433.54 ± 92.6 mm3, P < 0.05). There were no significant differences of lateral root resorption volume when comparing the impacted canines being on the labial or palatal sides (P > 0.05), but impacted canine angulation was significantly steeper on the labial side (70.85°) than on the palatal side (46.09°, P < 0.05). The volume of root resorption of laterals when comparing the various positions of the canine in different sectors or canine angulation in 30o intervals was not statistically significantly different (P > 0.05). CONCLUSIONS: The impacted canines caused root resorption of lateral incisors. The angulation of the canine was steeper on the labial side than on the palatal side but root resorption of adjacent laterals was not different. There were no statistically significant differences in the amount of root resorption of the laterals when the canine was evaluated according to localization and angulation.

Cephalometric comparison of cesarean and normal births.

OBJECTIVE: The aim of this study was to compare cephalometric variables of subjects with normal and cesarean births. MATERIALS AND METHODS: Ninety age- and gender-matched patients, who were treated in Gaziantep University, Faculty of Dentistry Orthodontics Department were equally divided into normal and cesarean groups according to the birth methods reported by their mothers. To eliminate the negative effects of being different in terms of age and gender among parameters, control, and patient groups were matched in the present study. Pretreatment cephalometrics radiographs were used. Six measurements representing sagittal and vertical relationships were evaluated from pretreatment cephalograms using Dolphin Imaging Orthodontics Software was used in this issue by an orthodontist. Kolmogorov-Smirnov test, Student's t-test, and Mann-Whitney U-test were used for statistical comparisons. RESULTS: A point-nasion-B point angle (ANB) and Wits values were higher in the normal group, while sella-nasion-A point angle, sella-nasion-B point angle, Frankfort horizontal-mandibular plane angle, and gonion-gnathion-SN plane angle values were higher in the cesarean group. However, the groups showed no significant differences (P > 0.05). ANB angle and Wits values showed high correlation. CONCLUSIONS: Within the study limitations, the results suggest that the birth method may not have a considerable effect on the development of the craniofacial skeletal system.

Effect of different temporary crown materials and surface roughening methods on the shear bond strengths of orthodontic brackets.

OBJECTIVE: The aim of this study was to evaluate the effect of different temporary crown materials (TCMs) and surface roughening methods on the shear bond strength (SBS) of orthodontic brackets. BACKGROUND DATA: TCMs are widely used during orthodontic treatment in teeth in need of prosthetic treatment, to prevent damage to the final restoration. However, there is no consensus considering the best method for roughening of the surface of TCMs. METHODS: Five different TCMs [Dentalon Plus-(D), Basworth Trim II-(B), Voco Structure Premium-(V), 3M ESPE Protempt 4-(P), and Revotek LC-(R)] were used in this study. Different surface roughening methods (37% phosphoric acid, sandblasting, and Er:YAG laser) were employed in three subgroups (n=20). The SBS test was used to assess the durability of all groups. Scanning electron microscopy (SEM) analysis was performed on a representative specimen in each group. RESULTS: The highest mean SBS value was observed in group V, followed by groups D and P, regardless of the surface treatment. The lowest SBS values were observed in group B. The laser-irradiated groups had higher SBS values than the sandblasted and acid-etched groups. Furthermore, a significant difference in SBS values was observed between the laser-irradiated group V and all other groups (p<0.005). CONCLUSIONS: The effects of the chemical nature of TCMs on the SBS values appeared to be clinically negligible, whereas the type of surface treatments had a significant influence on bond strengths. Er:YAG laser irradiation caused a significant increase in bond strength between the TCMs and orthodontic brackets.

Comparison of Bolton analysis and tooth size measurements obtained using conventional and three-dimensional orthodontic models.

OBJECTIVES: The aim of this study was to compare the accuracy, reproducibility, efficacy and effectiveness of measurements obtained using digital models with those obtained using plaster models. MATERIALS AND METHODS: A total of 20 digital models were produced by the Ortho Three-dimensional Models (O3DM) Laboratory and their software (O3DM version 2) was used to obtain measurements. Identical plaster models were used to obtain measurements of teeth with a vernier caliper. The maximum mesiodistal width of each study model, from first molar to first molar, was measured. All measurements were repeated at least 1 month later by the same operator for both digital and manual methods. The data were analyzed using Cronbach α, Wilcoxon signed rank test and the McNemar test. RESULTS: Cronbach α value of the data at T1 and T2 for 6 anterior and 12 overall teeth measured using the two methods was very close to the ideal value of 1, indicating high intra-observer reliability. The Wilcoxon signed rank test showed statistically significant differences between the two methods (P = 0.000, P < 0.001). The measurements obtained using the digital models were lower than those obtained using the plaster models. No statistically significant differences were found between the two methods for anterior Bolton discrepancies (P = 0.375) or overall Bolton discrepancies (P = 0.00). Paired comparisons of repeated measurements for Bolton ratios showed no statistically significant differences for anterior or overall Bolton discrepancies (P = 0.688 and P = 0.375, respectively). CONCLUSIONS: Use of O3DM software is an acceptable alternative to the traditional vernier caliper method in orthodontic practice.

Effect of Er:YAG laser pulse duration on shear bond strength of metal brackets bonded to a porcelain surface.

OBJECTIVE: The aim of this study was to compare the effect of different Er:YAG laser pulse durations on the shear bond strength (SBS) of metal brackets bonded to porcelain with two different adhesive systems. BACKGROUND DATA: Orthodontic brackets do not bond well to feldspathic porcelain surfaces, using resin cement. Various treatment methods have been suggested for the porcelain surface to improve bond strength. Thus far, no orthodontic study has evaluated the effect of different Er-YAG laser pulse durations on porcelain surfaces with or without sandblasting. METHODS: In the present study, 150 porcelain crowns were assigned to 10 groups differing in adhesive system and surface treatment. In five groups, the adhesive system was RelyX(™) U 200 and in the other five, Transbond XT was used. For each adhesive system, the porcelain surfaces were treated in one of five different ways: sandblasted, Er:YAG laser short pulse (SP), Er:YAG laser super short pulse (SSP), sandblasted+SP, or sandblasted+SSP. The sandblasted group with Transbond XT served as the control. SBS test was conducted for each group. Samples were examined by scanning electron microscopy. ANOVA and independent t test were used for statistical analysis. RESULTS: The control group had increased roughness and the highest SBS. Er:YAG laser application to the sandblasted porcelain flattened the roughness, and the effects of SP and SSP were similar. CONCLUSIONS: Er:YAG laser application did not allow for elimination of the hydrofluoric acid step. RelyX U 200 is a viable alternative to Transbond XT on sandblasted porcelain.

Effects of water flow rate on shear bond strength of orthodontic bracket bonded to enamel surface after Er:YAG laser ablation.

OBJECTIVE: The aim of present study was to evaluate the effect of water flow rate on enamel surface roughness and shear bond strength (SBS) of orthodontic brackets after Er:YAG laser ablation. BACKGROUND DATA: It is well known that external water supply is a fundamental requirement for Er:YAG laser efficiency on dental hard tissues. However, there is no consensus considering the water flow rate used during Er:YAG laser ablation. METHODS: Eighty sound human upper premolar teeth were used in the present study. Seventy-six teeth were assigned into four groups according to surface treatments. The 37% phosphoric acid-etched group served as the control. Er:YAG laser irradiation was performed in three subgroups with water flow rates of 25, 36, and 48 mL/min, respectively. All specimens were subjected to a SBS test. One specimen from each different surface treatment modality was examined by scanning electron microscopy. Kruskal-Wallis test was used to compare the SBS value of each group. RESULTS: Although the control group had the highest SBS value, statistically no significant differences were found among groups. CONCLUSIONS: Er:YAG laser application with a water flow rate of 48 mL/min produced better enamel surface alterations without any thermal damage to yield higher SBS values.

Comparison of retention characteristics of Essix and Hawley retainers.

OBJECTIVE: We aimed to compare the retention characteristics of Essix and Hawley retainers. METHODS: Adolescents undergoing fixed appliance treatment at 2 centers were recruited for this study. Twenty-two patients (16 women and 6 men) wore Essix retainers (Essix group) while 20 (14 women and 6 men) wore Hawley retainers (Hawley group). The mean retention time was 1 year, and the mean follow-up recall time for both groups was 2 years. Two qualified dental examiners evaluated the blind patient data. Maxillary and mandibular dental casts and lateral cephalograms were analyzed at 4 stages: pretreatment (T1), post-treatment (T2), post-retention (T3), and follow-up (T4). RESULTS: The results revealed that Essix appliances were more efficient in retaining the anterior teeth in the mandible during a 1-year retention period. The irregularity index increased in both arches in both groups after a 2-year post-retention period. The mandibular arch lengths increased during treatment and tended to return to their original value after retention in both groups; however, these changes were statistically significant only in the Hawley group. Cephalometric variables did not show any significant differences. CONCLUSIONS: The retention characteristics of both Essix and Hawley retainers are similar.