Histomorphometric evaluation of the effects of mandibular advancement appliance and low level laser therapy (LLLT) with different doses on condylar cartilage and subchondral bone in rats / Evaluación histomorfométrica de los efectos del aparato de avance mandibular y la terapia con láser de bajo nivel (TLBN) con diferentes dosis en cartílago condilar y hueso subcondral en ratas

The aim of this study was to evaluate the effects of mandibular advancement appliance and low level laser therapy (LLLT) with different doses on cellular hypertrophic changes in the mandibular condyle of rats. Forty-eight 8-week-old male Wistar albino rats weighing between 260 and 280 g were randomly divided into four experimental and control groups. Group I was the control group; group II was the mandibular advancement appliance group; group III was the 8 J/cm2 (0.25 W, 20 s) laser irradiation with mandibular advancement appliance group; and group IV was the 10 J/cm2 (0.25 W, 25 s) laser irradiation with mandibular advancement appliance group. Mandibular condyle cartilage and subchondral bone changes with different LLLT dose and mandibular advancement appliance were evaluated by histomorphometrical analysis. Subchondral bone fraction results showed that there were no significant differences between groups (p<0.05). The statistically significant differences found between control group and experimental groups in anterior and posterior cartilage layers thickness (p<0.05) and (p<0.01). Posterior and anterior condylar cartilage layers of rats react differentially to LLLT and mandibular advancement application. Maximum changes in condylar cartilage layers were found in 8 J/cm2 laser irradiation with mandibular appliance group.

El objetivo de este estudio fue evaluar los efectos del aparato de avance mandibular y la terapia con láser de bajo nivel (TLBN) con diferentes dosis sobre los cambios hipertróficos celulares, en el cóndilo mandibular de ratas. Cuarenta y ocho ratas albinas macho Wistar de 8 semanas de edad con un peso de 260 y 280 g se dividieron aleatoriamente en cuatro grupos experimentales y control. El grupo I control; grupo II, dispositivos de avance mandibular; grupo III de irradiación con láser de 8 J / cm2 (0.25 W, 20 s) con el grupo dispositivos de avance mandibular; y grupo IV con irradiación láser de 10 J / cm2 (0,25 W, 25 s) con el grupo de dispositivos de avance mandibular. El cartílago del cóndilo mandibular y los cambios en el hueso subcondral con diferentes dosis de TLBN y dispositivo de avance mandibular, se evaluaron mediante análisis histomorfométrico. Los resultados de la fracción ósea subcondral indicaron que no hubo diferencias significativas entre los grupos (p <0,05). Las diferencias estadísticamente significativas encontradas entre el grupo control y los grupos experimentales, en el grosor del cartílago anterior y posterior (p<0,05) y (p<0,01). Las capas de cartílago condilar posterior y anterior de las ratas reaccionan de manera diferencial a la aplicación de TLBN y avance mandibular. Se encontraron cambios significativos en las capas de cartílago condilar con irradiación láser de 8 J /cm2 con el grupo de dispositivos mandibulares.

The Effects of Using Plaque-Disclosing Tablets on the Removal of Plaque and Gingival Status of Orthodontic Patients.

OBJECTIVE: The aim of this study was to investigate the effects of using plaque-disclosing tablets (PDTs) on the plaque and gingival index scores of patients wearing fixed orthodontic appliances. METHODS: In group A (n=16), the subjects were motivated by conventional oral hygiene instructions, including verbal information about tooth brushing. The patients in group B (n=17) were motivated using PDTs used in the dentists' office to show the locations of biofilms in addition to the instructions given to group A. Both the chairside demonstration performed in group B and the at-home use of disclosing tablets were undertaken by those in group C (n=15). The periodontal parameters were recorded before applying the fixed appliance (T0) and after the first (T1) and third (T2) months. RESULTS: The plaque index (PI) scores of group C were significantly lower (p<0.05), when compared to groups A and B, after the first (T1) and third months (T2); however, no significant differences (p>0.05) were found between groups A and B. The gingival status of group C did not change significantly (p>0.05) over the three months and was statistically lower when compared to groups A and B. CONCLUSION: The use of PDTs at home may enhance the plaque removal efficiency and gingival health stability, by facilitating self-examination.

Evaluation of maxillary sinus volume and dimensions in different vertical face growth patterns: a study of cone-beam computed tomography.

OBJECTIVE: This study aimed to compare sinus volume and dimensions in patients with high-, low-, and normal-angle vertical growth patterns using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: According to skeletal vertical face growth patterns, 60 adults (31 female, 29 male, average age: 29.90 ± 10.91 years) were divided into three groups equally: high-angle, low-angle, and normal-angle groups. Cephalometric tracings were obtained from CBCT images and SN-GoGn (angle between Sella-Nasion line and Gonion-Gnathion line) cephalometric angular measurements used for the classification of skeletal vertical pattern evaluations. Morphological and dimensional changes in the maxillary sinuses were evaluated on CBCT images. Data were analyzed using the one-way ANOVA, Kruskall-Wallis, and Mann-Whitney U statistical tests. RESULTS: There were no statistically significant differences among the groups in terms of age (p > .05). The low-angle vertical growth pattern group showed significantly better results than the high-angle group in the right maxillary sinus length parameter (p < .05). CONCLUSION: According to the results, the high-angle subjects showed statistically lower values in terms of maxillary sinus length and width than the low-angle subjects. There were no effects of vertical face development on right and left maxillary sinus volumes. The results of this study may be useful in maxillary sinus evaluation when planning for orthognathic surgery and orthodontic mini screw application in various vertical face patterns.

Relationship between head posture and the severity of obstructive sleep apnea.

INTRODUCTION: The objective of this study was to compare the head posture of patients with obstructive sleep apnea (OSA) having different levels of severity with that of control subjects. METHODS: One hundred subjects participated in this study. Seventy-five subjects underwent overnight polysomnography in a sleep laboratory and were allocated into "mild," "moderate," or "severe" OSA groups, and 25 subjects with no complaints regarding OSA were allocated into 1 group and served as the controls. Cephalometric radiographs were obtained from all participants in natural head position. Craniocervical, craniovertical, and cervicovertical angles were measured in the groups. Data were analyzed using the least significant difference. RESULTS: The results showed significant differences between the OSA groups and the control group, and among the test groups, in all craniocervical, craniovertical, and cervicovertical angles (P <0.05), except for 1 craniovertical measurement (P >0.05). There were no significant differences in this measurement among the test groups and in any measurement between the mild and moderate OSA groups (P >0.05). CONCLUSIONS: Head posture showed significant differences in patients with OSA. In general, the more severe the OSA, the more extended the natural head position as indicated by increases in the craniocervical angles. The cervical posture parameters may indicate existing OSA.

The effect of fixed appliances on oral malodor from beginning of treatment till 1 year.

BACKGROUND: Orthodontic appliances can enhance plaque accumulation, and this can cause gingival inflammation. Halitosis of oral origin is associated with microbial metabolism on the tongue and in the saliva, dental plaque, and the amount of volatile sulfide-containing compounds. This study used a Halimeter to investigate fixed orthodontic therapy-associated increases in the oral malodor over a year. METHODS: Thirteen orthodontic patients with Angle Class I malocclusions receiving fixed orthodontic therapy formed the study group, and 12 dental students without any dental treatment formed the control group. The Halimeter was used to examine oral malodor by detecting volatile sulfur compounds (VSC). Plaque index (PI), gingival index (GI), and probing pocket depth (PPD) were also measured in both groups. The subjects in the study group had one visit before the orthodontic treatment started and seven visits during orthodontic therapy (1, 3, 5, 7, 9, 11, and 13 months after bonding), while the subjects in the control group had three visits, once per subsequent month. RESULTS: Oral malodor was significantly increased in the fixed orthodontic treatment group during treatment (p < .05). Increases were also observed in the PI, GI, and PPD measures (p < .05). The results of the control group were stable (p > .05). CONCLUSION: Oral malodor increased during fixed orthodontic treatments and reached a critical level 7 months later.

Does the Seating Force Affect the Shear Bond Strength of Brackets? An InVitro Study.

OBJECTIVE: The purpose of this study was to observe two different seating forces on conventional and self-ligating brackets using shear bond strength (SBS). METHODS: The study material consisted of 48 recently extracted human premolars divided into four groups: Group I, conventional bracket (Master series, AO) 100 g seating force applied; Group II, conventional bracket (Master series, AO) 200 g seating force applied; Group III, self-ligating bracket (Empower, AO) 100 g seating force applied; and Group IV, self-ligating bracket (Empower, AO) 200 g seating force applied. All teeth were bonded with Transbond XT by the same operator. Following the bonding procedure, all teeth were stored in deionized water at 37°C for 30 days, and they were thermal cycled. A universal testing machine was used to obtain the SBS records. The Kruskal-Wallis statistical test was used to determine the significant differences in SBS between the four groups, and the Mann-Whitney U test with Bonferroni correction was used to compare the subgroups. RESULTS: The mean shear bond strength was 15.70 MPa for Group I, 13.97 MPa for Group II, 8.38 MPa for Group III, and 8.31 MPa for Group IV. Significant differences in the SBS values were recorded between the self-ligating groups and conventional bracket groups. Seating forces on the brackets did not show any differences among the groups. CONCLUSION: Within the limitations in this study, 100 g and 200 g forces can be applied because both seating forces showed acceptable SBS results.

Evaluation of Patients with Cleft Lip and Palate in Southeastern Anatolian Region.

OBJECTIVE: Our study included patients with cleft lip and palate who applied to Gaziantep University Dentistry Faculty Orthodontics Department between 2010 and 2014. The aim of this study was to reveal the characteristics of these patients with demographic values. METHODS: In total, 118 patients were included in this study. The patients were pursued by phone calls, and the study was conducted with only 64 patients. The demographic map was created with a statistical expert as a questionnaire. RESULTS: It was thought that the reason for not being able to include the remaining 54 patients was a change in phone number, designation, or others. One patient who was to be interviewed died because of heart failure. The results revealed that the place of birth of 18.75% patients was a metropolitan region that of 54.68% was a province, that of 21.87% was a district, and that of 4.69% was a village. The majority of patients (93.25%) had a low family income level. The average number of children was 3.28, and readership was 1.47. The rate of working mothers was 1.56%. CONCLUSION: It was concluded that the cleft lip and palate patient group had lower economic and sociocultural levels. For this purpose, raising awareness of parents and providing financial support to families are required because of the long-term treatment process. It was thought that the long-term treatment process of these patients in a single-unit authority with the guidance of universities would be appropriate for better patient follow-up and inventory. Otherwise, as seen in this study, contact cannot be established after a while and some problems can arise with regard to follow-up. Lack of communication can lead to the formation of more difficult patients with growth and development.

Dental technician pneumoconiosis mimicking lung cancer.

A 47-year-old man was referred for assessment of bilateral lymph node enlargement identified on a routine chest radiograph. Positron emission tomography showed high standardized uptake values (SUVmax: 20.5) in right supraclavicular, right intercostal, and multiple mediastinal lymph nodes. Biopsy samples obtained from the right upper and left lower paratracheal nodes by mediastinoscopy revealed granulomatous inflammation. Clinical and laboratory findings indicated a diagnosis of dental technician pneumoconiosis. The patient is alive and well 3 years after diagnosis. This case highlights the importance of obtaining an occupational history.

The effects of low-level laser therapy on condylar growth with a mandibular advancement appliance in rats.

OBJECTIVE: The aim of this study was to evaluate the effects of low-level laser therapy (LLLT) on condylar growth with a mandibular advancement appliance in rats. BACKGROUND DATA: Researchers studied new methods such as laser, for mandibular condyle growth stimulation and acceleration with or without functional appliances in experimental animals, but the specific mechanism and laser energy density values for condylar biostimulation and bone cell activities are still unknown. METHODS: Forty-eight 8-week-old male Wistar albino rats weighing between 260 and 280 g were randomly divided into four groups. Group I was the control group; group II was the mandibular advancement appliance group; group III was the 8 J/cm(2) (0.25 W, 20 sec) laser irradiation with mandibular advancement appliance group; and group IV was the 10 J/cm(2) (0.25 W, 25 sec) laser irradiation with mandibular advancement appliance group. Experimental rats in groups III and IV were stimulated with a low-level laser in the temporomandibular joint region bilaterally 15 times over 30 days. Morphological changes in the mandible were evaluated with lateral radiographs before and after the study with selected linear and angular measurements. Pearson correlation test, Friedman, Kruskal-Wallis, and Mann-Whitney U tests were used for statistical analysis. RESULTS: According the lateral radiograph results, the growth of mandibles in the experimental groups was significantly more than that of the control group (p<0.05). Group III also showed greater mandibular growth than the other groups (p<0.05). CONCLUSIONS: We concluded that an intraoral appliance with LLLT, including chosen parameters, can stimulate condylar growth and increase mandibular advancement.

Effects of low-level laser therapy on changes in inflammation and in the activity of osteoblasts in the expanded premaxillary suture in an ovariectomized rat model.

BACKGROUND AND OBJECTIVE: Osteoporosis is a progressive systemic skeletal disease characterized by reduced bone mass/density and microarchitectural deterioration of bone tissue. Bone formation initially exceeds bone resorption, but by the third decade, such formation is reversed, resulting in a net loss of bone mass. This resorption, in turn, increases bone fragility and susceptibility to fracture. This study aimed to evaluate the effects of low-level laser therapy (LLLT) on bone regeneration in the expanded premaxillary suture in an ovariectomized rat model. METHODS: Thirty-two 12-week-old female Wistar albino rats were used in the experiment. All of the animals underwent ovariectomy 3 months before the experiment. Expansion appliances were affixed to the maxillary incisors for the expansion of premaxillary sutures. The premaxillary sutures of the laser group were exposed to 5 J/cm(2) laser energy, and no treatment was performed for the controls. All the rats in both groups were euthanized on either the 7th day (n=8) [end of expansion period; Laser Group 1(LG1) and Control Group 1 (CG1)] or the 17th day (n=8) [end of retention period; Laser Group 2 (LG2) and Control Group 2 (CG2)], respectively, for histological assessment. RESULTS: Histological findings indicated that the LG1 group showed a significantly higher number of osteoblasts than did the CG1 group (p=0.028). The CG1 and CG2 groups showed a significantly higher number of osteoclasts than did the LG1 and LG2 groups, respectively (p=0.005), (p=0.032). The LG2 group exhibited a capillary increase similar to that of the other groups, without statistically significant differences. CONCLUSIONS: On the basis of our methodology and results, we conclude that low-level laser associated with rapid maxillary expansion influences bone regeneration in sutures, thereby accelerating healing, even in ovariectomized rats. We found that LLLT decreased osteoclastic activity in the ovariectomized rats. Therefore, preventing osteoporosis necessitates further investigations to clarify the effect of LLLT on postmenopausal patients.

Effects of bite-jumping appliances on mandibular advancement in growing rats: A radiographic study.

OBJECTIVE: The aim was to evaluate the effects of the use of mandibular advancement appliances on mandibular growth in growing rats. MATERIALS AND METHODS: Twenty-four 8-week-old male Wistar albino rats were randomly divided into two experimental groups (12 rats each): Group I was a control group, and Group II was the mandibular advancement appliance group. A functional bite-jumping appliance was used in Group II to promote mandibular advancement. Anatomical changes in the condyle and mandible were evaluated by comparing radiographic results from before and after the study, with angular and linear measurements. Friedman and Mann-Whitney U-tests were used in statistical analysis. RESULTS: According to the radiographic results, the growth of mandibles and condyles in Group II was significantly greater than with the length of the condylar process (A-B) and distance from condyle to menton (A-D) variables (P < 0.05). In addition, Group I showed greater mandibular base growth than did Group II (P < 0.05). CONCLUSIONS: We conclude that the use of an intraoral bite-jumping appliance can stimulate condylar growth and increase sagittal mandibular advancement in growing rats.

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.

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.

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.

Metrical and histological investigation of the effects of low-level laser therapy on orthodontic tooth movement.

The aim of this study was to evaluate the effects of 820-nm diode laser on osteoclastic and osteoblastic cell proliferation-activity and RANKL/OPG release during orthodontic tooth movement. Thirty-eight albino Wistar rats were used for this experiment. Maxillary incisors of the subjects were moved orthodontically by a helical spring with force of 20 g. An 820-nm Ga-Al-As diode laser with an output power of 100 mW and a fiber probe with spot size of 2 mm in diameter were used for laser treatment and irradiations were performed on 5 points at the distal side of the tooth root on the first, second, and 3rd days of the experiment. Total laser energy of 54 J (100 mW, 3.18 W/cm(2), 1717.2 J/cm(2)) was applied to group II and a total of 15 J (100 mW, 3.18 W/cm(2), 477 J/cm(2)) to group III. The experiment lasted for 8 days. The number of osteoclasts, osteoblasts, inflammatory cells and capillaries, and new bone formation were evaluated histologically. Besides immunohistochemical staining of PCNA, RANKL and OPG were also performed. No statistical difference was found for the amount of tooth movement in between the control and study groups (p > 0.05). The number of osteoclasts, osteoblasts, inflammatory cells, capillary vascularization, and new bone formation were found to be increased significantly in group II (p < 0.05). Immunohistochemical staining findings showed that RANKL immunoreactivity was stronger in group II than in the other groups. As to OPG immunoreactivity, no difference was found between the groups. Immunohistochemical parameters were higher in group III than in group I, while both were lower than group II. On the basis of these findings, low-level laser irradiation accelerates the bone remodeling process by stimulating osteoblastic and osteoclastic cell proliferation and function during orthodontic tooth movement.

Does the panoramic radiography have the power to identify the gonial angle in orthodontics?

PURPOSE: The objective of this study was to assess gonial angle under the angle classification by comparing panoramic radiograph and lateral cephalometric radiograph. MATERIALS AND METHODS: 49 patients (25 males, 24 females) with an age range of 12-29 years participated in the present study. Subjects were retrospectively selected among those categorised as skeletal and dental Class I, II, and III malocclusion group. Using lateral cephalometric radiograph, mandibular and ramal planes were drawn and based on these planes. Gonial angle was determined from two tangents which were drawn from the inferior border of the mandible and posterior borders of the condyle and ramus of both sides in the panoramic radiographs. Multiple comparison tests (ANOVA) were used to determine differences between the three angle groups. RESULTS: There were no significant differences between Class I, II, and III malocclusion group values of gonial angles determined by lateral cephalometric radiograph and panoramic radiographs (P > 0.05). CONCLUSION: Panoramic radiograph results were shown to be as reliable as lateral cephalometric radiograph in all angle classifications. Panoramic radiography can be used as an alternative radiographic technique to detect gonial angle in orthodontic patients.

Effect of fixed appliances on oral malodor.

INTRODUCTION: The objective of this study was to evaluate the effect of fixed appliances on oral malodor. METHODS: Forty-one patients participated in this study. They were randomized into 2 groups: treated with fixed orthodontic appliances and untreated controls. Oral malodor measurements and the gingival and plaque indexes were recorded in each group by same periodontist. Measurements were taken from the study group before bonding, 1 week after bonding, and 4 weeks after bonding. The control group's measurements were made at the same time. RESULTS: Oral malodor and the gingival and plaque indexes were significantly increased 1 week after bonding (P <0.05). Oral malodor was increased at 4 weeks after bonding (P >0.05). The comparison of the groups showed differences 1 week and 4 weeks after bonding. CONCLUSIONS: The oral malodor reached the critical level during fixed orthodontic treatment. Oral malodor could indicate a need to evaluate oral health and remind patients of the importance of maintaining ideal oral hygiene.

Effect of chlorhexidine gluconate, Clearfil Protect Bond, and KTP laser on microleakage under metal orthodontic brackets with thermocycling.

OBJECTIVE: The purpose of this study was to evaluate the effects of antimicrobial pretreatments [chlorhexidine gluconate (CHX), Clearfil Protect Bond (CPB), and potassium-titanyl-phosphate (KTP) laser] on microleakage under metal orthodontic brackets. MATERIALS AND METHODS: Sixty freshly-extracted human premolars were randomly assigned to four equal groups: group 1, 37% phosphoric acid; group 2, 37% phosphoric acid + 2% CHX; group 3, 37% phosphoric acid + KTP laser; and group 4, CPB. The teeth were kept in distilled water for 24 h, and thereafter subjected to 500 thermal cycles. Then specimens were sealed with nail varnish, stained with 0.5% basic fuchsin for 24 h, sectioned, and evaluated under a stereomicroscope. Microleakage was scored with regard to the adhesive-tooth interface and the bracket-adhesive interface at both incisal and gingival margins by the same person. Statistical analysis was accomplished by one-way ANOVA and the Kruskal-Wallis test, with significance set at p = 0.05. RESULTS: Microleakage was observed in all groups. No statistically significant difference was observed among all groups in terms of microleakage when bracket-adhesive and bracket-enamel interface along both gingival and incisal margins was evaluated (p > 0.05). CONCLUSIONS: The lowest microleakage scores were observed in the control group. CPB, KTP, and CHX groups did not show significant differences with the control group (p > 0.05), but the mean scores of the CHX group were higher than those of the other two experimental groups.

Shear Bond Strength of Orthodontic Brackets Cured with Different Light Sources under Thermocycling.

OBJECTIVES: The aim of this study was to compare the shear bond strength (SBS) of two different light sources under different thermal cycle frequencies. METHODS: Ninety human premolar teeth were divided into six groups, in which three groups consisted of halogen groups - Group I was cured with halogen without thermocycle, Group II cured with halogen with 500 thermocycles, and Group III cured with halogen with 10,000 thermocycles. The other three groups consisted of Plasma arc (PAC) group - Group IV was cured with PAC without thermocycle, Group V cured with PAC thermocycled 500 cycles, and Group VI cured with PAC thermocycled 10,000 cycles. Two way ANOVA was used to compare the SBS between the groups, and chi square-test was used to compare the bond failure of ARI scores among the groups. RESULTS: A significant difference was found for curing lights (P<.001) and thermocycling (P<.01). However, there was no interaction between light curing and thermocycling (P=.177). The halogen groups demonstrated higher mean SBS than the PAC groups. Both groups showed a significant reduction between no cycles and 10,000 cycles (P<.05). CONCLUSIONS: Both light sources showed favorable SBS performance without the thermocycle procedure. Thermocycling significantly decreased the SBS values of both groups.

Comparison of the effects of RME and fan-type RME on nasal airway by using acoustic rhinometry.

OBJECTIVE: To evaluate and compare the nasal airway changes following rapid maxillary expansion (RME) and fan-type RME using acoustic rhinometry (AR). MATERIALS AND METHODS: The study sample consisted of three groups. The RME group comprised 15 subjects with maxillary transverse discrepancies and posterior crossbites. The fan-type RME group comprised 15 subjects, who had an anteriorly constricted maxilla with a normal intermolar width. The third group included 15 patients who had an ideal occlusion and received no orthodontic treatment and served as the control group. AR was used to measure nasal volume and the minimal cross-sectional area (MCA) before expansion (T1), after expansion (T2), and 6 months after expansion (T3). Each AR recording was performed with and without the use of a decongestant. Two-way analysis of variance was used to determine differences among the groups and three-way analysis of variance was used for the differences between groups. If evidence of statistically significant differences was found, a Bonferroni test was used. RESULTS: The results showed that nasal volume and MCA were significantly increased with RME and fan-type RME immediately after expansion (P < .05). At the end of retention, nasal volume and MCA values of RME showed significant differences with both expansion fan-type RME and control groups (P < .05). CONCLUSIONS: RME and fan-type RME had similar effects on the nasal airway immediately after expansion. The increase in nasal volume and MCA was more stable in the RME group than in the fan-type RME group at the end of the retention period.