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.

Temperature changes of pulp chamber during in vitro laser welding of orthodontic attachments.

The use of lasers has been suggested for orthodontists to fabricate or repair orthodontic appliances by welding metals directly in the mouth. This work aimed to evaluate the temperature changes in the pulp chamber during welding of an orthodontic wire to an orthodontic molar band using Nd : YAG laser in vitro. A freshly extracted human third molar with eliminated pulpal tissues was used. J-type thermocouple wire was positioned in the pulp chamber. A conductor gel was used in the transferring of outside temperature changes to the thermocouple wire. An orthodontic band was applied to the molar tooth and bonded using light cured orthodontic cement. Twenty five mm length of 0.6 mm diameter orthodontic stainless steel wires was welded to the orthodontic band using Nd : YAG laser operated at 9.4 watt. Temperature variation was determined as the change from baseline temperature to the highest temperature was recorded during welding. The recorded temperature changes were between 1.8 and 6.8°C (mean: 3.3±1.1°C). The reported critical 5.5°C level was exceeded in only one sample. The results of this study suggest that intraoral use of lasers holds great potential for the future of orthodontics and does not present a thermal risk. Further studies with larger samples and structural analysis are required.

Effects of edentulism on mandibular morphology: evaluation of panoramic radiographs.

PURPOSE: The objective of this study was to evaluate morphological changes of the mandible in edentulous and dentate subjects using panoramic radiographs. MATERIALS AND METHODS: Panoramic radiographs were divided into the following three groups: Group I (completely edentulous group), Group II (old dentate group) and Group III (young dentate group). The research parameters of gonial angle, condylar height, ramus height, ramus notch depth, and antegonial notch depth were measured on panoramic radiographs. The Kruskal-Wallis statistical test was used to determine significant differences in mandibular morphological parameters among the three groups. The Mann-Whitney U test was used to compare the subgroups. RESULTS: Significant differences were found only in ramus height between three groups. According to the Mann-Whitney U test, a significant difference was exhibited among Groups I and II in the ramus height parameter. No significant differences were found in the gonial angle, condylar height, ramus notch depth, or antegonial notch depth when comparing the young dentate, old dentate, and completely edentulous subjects. CONCLUSIONS: Significant differences were found only in ramus height between the groups. Ramus height may be an indicator that changed by years and tooth loss. It must be considered that ramus height can be decreased in edentulism.

PAX9 polymorphisms and susceptibility with sporadic tooth agenesis in Turkish populations: a case-control study.

BACKGROUND: Hypodontia, the congenital absence of one or a few teeth is one of the most common alterations of the human dentition. Familial hypodontia is caused by mutations in PAX9, Msx1 and Axin2 genes. Limited numbers of studies are present to show etiological factors beyond this anomaly in Turkish community belonging to Caucasian racial family. The purpose of this study is to investigate the relationships between the two different single nucleotide polymorphisms that are G-1031A and T-912C with hypodontia in Caucasians. 200 individuals having hypodontia and 114 normal individuals having all 32 teeth present were selected for the study. Blood samples were collected from each individual and DNA was extracted. To determine the polymorphisms, PCR-RFLP method was used. RESULTS: The outcomes suggest that the individuals having AC haplotype carry less risk in having hypodontia compared with the rest of the haplotype groups (OR = 3.88; CI = 95%; p = 0.001). The ratio of GT haplotype is less in the hypodontia group meaning that the GT carriers are in risk group in terms of hypodontia risk. CONCLUSION: These results indicate that polymorphisms in the promoter region of PAX9 gene may have an influence on the transcriptional factors and activity of this gene and are associated with hypodontia in Caucasian individuals.

Identification of various orthodontic materials as foreign bodies via panoramic radiography, cone beam computed tomography, magnetic resonance imaging, and ultrasonography: an in vitro study.

OBJECTIVES: We evaluated the in vitro detection sensitivity of orthodontic materials (serving as foreign bodies) using panoramic radiography, cone beam computed tomography (CBCT), magnetic resonance imaging (MRI), and ultrasonography. METHODS: Five different orthodontic materials served as foreign bodies: titanium-molybdenum alloy wire (TMA; ORMCO, Orange, CA, USA; 0.017 × 0.025 in in cross-sectional dimensions and 1 cm long); stainless steel bracket tooth #34 (American Orthodontics, Sheboygan, WI, USA); a monocrystalline, sapphire ceramic bracket tooth #34 (Skyortho Dental Supplies Medical, China); a polycrystalline alumina clear bracket, Damon clear bracket tooth #34 (ORMCO); and a 1 × 1 × 0.1 cm polyurethane-based thermoplastic material, Invisalign clear aligner (Align Technology, San Jose, CA, USA). Panoramic radiography, CBCT, MRI, and ultrasonography were used, and four observers scored all findings independently. RESULTS: The TMA and stainless steel bracket were visualised in all fields by panoramic radiography and CBCT. The sapphire and Damon brackets were very clear on CBCT. The Invisalign in air was evident only on CBCT. MRI was unable to identify any material in muscle. Ultrasonography detected the TMA, sapphire bracket, and the Invisalign in muscle but only the TMA on bone. CONCLUSIONS: Panoramic radiography does not reveal nonmetallic orthodontic equipment in air and reveals them only poorly in muscle. CBCT was the optimal imaging modality for all materials in all fields except for the Invisalign in muscle and bone. CBCT was the only method that revealed the Invisalign in air. MRI and ultrasonography should be used to detect orthodontic materials in muscle.

In-vitro assessment of temperature rise in the pulp during orthodontic bonding.

INTRODUCTION: In this in-vitro study, we evaluated the temperature changes in the pulp chamber during bracket bonding using 4 different light sources. METHODS: Eighty intact extracted maxillary central incisors were used. The teeth were divided into 4 groups of 20 teeth each. Brackets (Mini Twin, Dentaurum, Ispringen, Germany) were bonded with Transbond XT (3M Unitek, Monrovia, Calif) adhesive and light cured with low-intensity halogen light for 40 seconds, high-intensity halogen light for 40 seconds, light-emitting diode (LED) light for 20 seconds, and plasma arc light (PAC) for 6 seconds. Light curing was performed 5 mm from tooth surfaces. A J-type thermocouple wire was positioned in the center of the pulp chamber. The results were analyzed with analysis of variance (ANOVA) and the Tukey HSD test. RESULTS: ANOVA and the Tukey HSD test showed that pulp chamber temperature changes were influenced by the type of light source. All groups showed significant differences between each other (P <0.001). The intrapulpal temperature changes induced by different light sources were the following: high-intensity halogen (6.84 degrees C +/- 2.44 degrees C), low-intensity halogen (4.71 degrees C +/- 0.96 degrees C), LED (2.95 degrees C +/- 1.12 degrees C), and PAC (0.96 degrees C +/- 0.83 degrees C). CONCLUSIONS: High- and low-intensity halogen light induced significantly higher intrapulpal temperature changes than did the LED and PAC. Except for the high intensity halogen light, orthodontic bonding with light-curing units did not exceed the critical 5.5 degrees C rise in temperature reported to produce pulpal damage.

Shear Bond Strength of Intraoral Laser Welding and its Effect on Intrapulpal Temperature Rise in Primary Teeth: An in Vitro Study.

OBJECTIVE: This study compared the shear bond strength (SBS) of conventional welding (CW) and intraoral laser welding (LW) on fixed space maintainers (SMs), and investigated the intrapulpal temperature change (ITC) during LW. BACKGROUND DATA: Lasers have been used for intraoral welding. MATERIALS AND METHODS: The SBS test used 26 molar bands divided into two groups, CW and LW. Stainless steel wires were welded to the middle of the buccal and lingual aspects of all the bands, using an Nd:YAG laser for the LW group and silver solder and flux soldering media for the CW group. The samples, fixed to acrylic resin blocks, were subjected to shear testing. In the ITC test, 25 exfoliated primary second molar teeth were used to adapt molar bands. J-type thermocouple wire was positioned in the pulp chamber. ITCs were determined during Nd:YAG laser welding of stainless steel wires to the bands. Mann-Whitney U test was used to determine differences in SBS between the groups. ITCs were analyzed by paired t test. RESULTS: The SBS between groups showed significant differences (LW: 489.47 ± 135.70; CW: 49.71 ± 17.76; p < 0.001). The mean ITC during LW was 3.64 ± 0.79 (min: 2.4; max: 5.10). None of the samples' ITCs exceeded the critical threshold value (5.5 °C). CONCLUSIONS: LW obtained a higher-strength joint than CW. ITCs during LW do not present a thermal risk to primary teeth. The intraoral use of LW for SMs in primary teeth is recommended in terms of strength and ITCs.

Histomorphometric evaluation of the effects of various diode lasers and force levels on orthodontic mini screw stability.

OBJECTIVE: The purpose of this study was to evaluate the effects of different laser dose and force levels on the stability of orthodontic mini screws used for anchorage, by histomorphometric analyses. BACKGROUND DATA: Low-level laser therapy speeds up blood flow, improves the mechanism of the revitalization processes, reduces the risk of infection, boosts metabolic activities, and accelerates the healing of the damaged tissue. Although there are many research studies about low-level laser therapy applications in a variety of areas, no investigations were found concerning mini screw stability using various laser dose levels with different force level applications. METHODS: Seventeen New Zealand white rabbits were used. A total of 68 cylindrical, self-drilling orthodontic mini screws were threaded at the fibula. Experimental subjects were divided into six groups; force application was not performed in the first three groups, whereas 150 g of force was applied via nickel-titanium closed-coil springs placed between two mini screws in the other three groups. Measurements of the initial torque values (10 Ncm) were manipulated by a digital portable torque gauge. Various low-level laser doses were applied to the groups during the postoperative 10 days. After 4 weeks, bone-to-implant contact and cortical bone thickness were histomorphometrically analyzed. RESULTS: In the 150 g force plus 20 J/cm(2) dosage group, the highest bone-to-implant contact values were observed. (p<0.05) There were no statistically significant correlations between cortical bone thickness and bone-to-implant contact values; on the other hand, no significant difference was found among the same groups in terms of cortical bone thickness values (p>0.05). CONCLUSIONS: Low-level laser therapy was noticed to induce the mini screw-bone contact area. Low-level laser therapy may be a supplementary treatment method to increase the stability of the orthodontic mini screw.

Inadequate shear bond strengths of self-etch, self-adhesive systems for secure orthodontic bonding.

This study evaluated the shear bond strength (SBS) of a traditional orthodontic bracket bonding agent (Transbond XT) against two self-etch, self-adhesive systems (Maxcem Elite and Vertise Flow). Sixty premolar teeth and sixty brackets were randomly and equally divided into five groups: Transbond XT (TXT) as the control, Maxcem Elite (ME) without etching, ME with etching (ME/ Etch), Vertise Flow (VF) without etching, and VF with etching (VF/Etch). Respective SBS results of the five groups were 9.86±3.20, 4.67±2.94, 7.82±2.56, 2.55±0.77, and 7.89±1.17 MPa. SBS values of the new self-etch adhesive systems were significantly lower than the traditional etch-and-rinse control (p<0.005). However, no significant differences were found between TXT and the self-adhesives applied with etching (p>0.005). After debonding, ARI scores "0" and "1" were predominant in non-etched ME and VF groups. It was concluded that new self-etch, self-adhesive bonding systems require additional phosphoric acid application to achieve comparable SBS values as the traditional orthodontic bonding agent.

Unusual cases of the transmigrated mandibular canines: report of 4 cases.

The canine impaction is not uncommon in dental literature, but the transmigration of mandibular canine is a rare phenomenon, and some of them are far more extreme than others. In this study, we aimed to present the more extreme cases of the four transmigrated mandibular canine cases with special emphasis on their classification.