3D Evaluation of the Relationship between Different Vertical Growth Patterns and Cranial Base Angulations.

Objective This study aimed to compare cranial base angulations in subjects with high-angle, low-angle, and normal-angle vertical growth patterns using cone beam computed tomography (CBCT). Design This study is a retrospective clinical research. Settings This study was carried out at the Dentistry Faculty of Eskisehir Osmangazi University. Participants According to skeletal vertical face growth patterns, 78 subjects (48 females and 30 males, average age: 13.19 ± 1.73 years) were divided equally into three groups: high angle, low angle, and normal angle groups. Main Outcome Measures Cephalometric images were derived from CBCT, and patients were classified according to the SN-GoGn angle (sella-nasion, gonion gnathion angle). Sagittal, axial, and coronal cranial base angulations were measured in three-dimensional (3D) CBCT images. Data were analyzed using the Kolmogorov-Smirnov normality, Kruskal-Wallis, and Mann-Whitney U statistical tests. Results There were statistically significant differences between the low-angle and high-angle groups according to sagittal cranial base angulation parameters ( p = 0.01). Conversely, there were no statistically significant differences between vertical facial growth patterns according to coronal and axial cranial angle variables ( p > 0.05). Conclusion According to the study results, there were no effects of cranial base angulations in two planes (coronal and axial) on different vertical skeletal growth patterns. In the sagittal cranial base angulation parameter, the high-angle group showed greater angulation values than the low-angle group. CBCT may be helpful for evaluating, diagnosing, and predicting 3D cranial base differences.

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.

Evaluation of the relationship between impacted canines and three-dimensional sella morphology.

PURPOSE: The purpose of this study was to assess the three-dimensional morphometric features of the sella turcica using cone beam computed tomography (CBCT) in subjects with unilateral and bilateral maxillary impacted canines and normal controls. METHODS: In this retrospective study, CBCT images captured with ultra-low dose protocol of 73 subjects (21 males, 52 females; mean age 20.01 ± 6.53 years) with unilateral or bilateral maxillary impacted canines (29 unilateral and 29 bilateral) and 15 controls were evaluated. Nineteen different measurements of the pituitary fossa were made on CBCT images. To evaluate the normality, the Kolmogorov-Smirnov test was used. The nonparametric statistical Kruskal-Wallis and Mann-Whitney U tests were applied to analyze the significant differences among and between the groups. Statistical significance was set at 5%. RESULTS: No measurement differed significantly among the groups (all p > 0.05) other than the right sella length, which differed between the unilateral and bilateral test groups and the unilateral test group and controls (both p < 0.05). The bilateral test group and control group did not differ significantly, but both exhibited greater right sella length than did the unilateral test group (p > 0.05). CONCLUSIONS: Other than the right sella length, there were no among-group differences in the mean pituitary fossa measurements of subjects with impacted unilateral and bilateral canines and normally erupted canines. The right sella length was lower in subjects with impacted unilateral canines than in those with bilateral impacted canines and normal controls.

Three-dimensional evaluation of angular, linear, and resorption features of maxillary impacted canines on cone-beam computed tomography.

OBJECTIVES: The aim of this study was to evaluate the localization, angulation, and resorption features of maxillary impacted canines on cone-beam computed tomography (CBCT). METHODS: This retrospective study examined the CBCT scans of 140 maxillary impacted canines in 102 patients (43 males, 59 females; mean age: 16.25 ± 6.31 years). The following impacted canine-related parameters were analyzed on the CBCT images: impaction side; location; root resorption levels of adjacent teeth; occlusal plane and midline distances of impacted canines; and angulations of impacted canines to midline, lateral incisor, and occlusal plane. RESULTS: Bilateral canine impaction was found in 38 subjects, and unilateral canine impaction was present in 64 subjects. Severe resorption was found in 14 canines. There were no significant differences between the occlusal plane and midline distances to the impacted canine cusp tip and root apex (p > 0.05). The midline angulation of right maxillary impacted canines was significantly higher than that of left maxillary impacted canines (p < 0.05), while the occlusal plane angulation of left maxillary impacted canines was significantly higher than that of right maxillary impacted canines (p < 0.05). CONCLUSIONS: Maxillary canine impaction was more frequently seen in female subjects than in male subjects. Lateral incisors were more frequently affected than first premolars, and slight resorption was more frequently seen in adjacent teeth. CBCT assessment of maxillary impacted canines can provide accurate measurements of angular, linear, and resorption parameters.

The Relationship between Dental Follicle Width and Maxillary Impacted Canines' Descriptive and Resorptive Features Using Cone-Beam Computed Tomography.

OBJECTIVES: To assess the relationship between dental follicle width and maxillary impacted canines' descriptive and resorptive features with three-dimensional (3D) cone-beam computed tomography (CBCT). METHODS: The study comprised 102 patients with cone-beam computed tomography 3D images and a total of 140 impacted canines. The association between maxillary impacted canine dental follicle width and the variables of gender, impaction side (right and left), localization of impacted canine (buccal, central, and palatal), and resorption of the adjacent laterals was compared. Measurements were analyzed with Student's t-test, Kruskal-Wallis test, and Mann-Whitney U statistical test. RESULTS: According to gender, no statistically significant differences were found in the follicle size of the maxillary impacted canine between males and females (p > 0.05). Widths of the follicles were determined for the right and left impaction sides, and no statistically significant relation was found (p > 0.05). There were statistically significant differences between root resorption degrees of lateral incisors and maxillary impacted canine follicle width (p < 0.05). Statistically significant higher follicle width values were present in degree 2 (mild) resorption than in degree 1 (no) and degree 3 (moderate) resorption samples (p < 0.05). CONCLUSIONS: No significant correlation was found between follicle width and the variables of gender, impaction side, and localization of maxillary impacted canines. Our study could not confirm that increased dental follicle width of the maxillary impacted canines exhibited more resorption risk for the adjacent lateral incisors.

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.

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.

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.

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.

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.

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.

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.