Evaluation of temporomandibular fossa and mandibular condyle in adolescent patients affected by bilateral cleft lip and palate using cone beam computed tomography.

The purposes of this study were to investigate the position of the mandibular condyle and temporomandibular fossa between the adolescent patients affected by bilateral cleft lip and palate (BCLP) and well-matched controls without any cleft by using cone-beam computed tomography (CBCT). The study sample consisted of 17 patients (7 females and 10 males; mean age, 14.27 ± 2.83 years) affected by BCLP and 17 patients (6 females and 11 males; mean age, 14.27 ± 2.12 years) as age-and sex-matched control group without any cleft. Using cone-beam computed tomography segmented three-dimensional temporomandibular fossa and mandibular condyle images were reconstructed and angular, linear, and volumetric measurements of the patients in both sides of the groups were examined using Paired and Student's t-tests. Comparison of the sides showed that both sides were found to be similar in BCLP and control groups, except the condylar angulation of the right side was found to be higher compared to that of the left side in both groups (p < 0.05). Comparison of the groups showed that the patients affected by BCLP and non-cleft patients had similar values for all parameters, except for the condylar angulation in the right side (BCLP group had less angulation compared to controls; p < 0.05). The condylar volume was found to be slightly less in the BCLP group in both sides compared to the controls (p > 0.05). The positions of the mandibular condyle and temporomandibular fossa were found to be similar in patients affected by BCLP and control group of without any cleft. SCANNING 38:720-726, 2016. © 2016 Wiley Periodicals, Inc.

Evaluation of the mandibular volume and correlating variables in patients affected by unilateral and bilateral cleft lip and palate: a cone-beam computed tomography study.

OBJECTIVES: The aims of the present study were to evaluate the mandibular volume in patients affected by unilateral (UCLP) and bilateral cleft lip and palate (BCLP) and to compare the findings with a well-matched normal occlusion sample without cleft. MATERIALS AND METHODS: The study sample consisted of 66 patients divided into UCLP (24 patients; mean age, 14.46 ± 3.24 years), BCLP (17 patients; mean age, 14.28 ± 2.85 years), and control (25 patients; mean age, 14.40 ± 2.81 years) groups. The volume of the mandible including the condyle and the roots of the teeth and craniofacial measurements were performed using cone-beam computed tomography and analyzed using the one-way variance analysis and post hoc Tukey's tests. Regression analyses were used to evaluate the relationships of the measurements and the mandibular volume. RESULTS: Patients affected by UCLP and BCLP had similar craniofacial features (p > 0.05), including decreased SNB, Co-A, Co-Gn, Co-Go, and Go-Gn and increased ANB and SN-MP measurements compared to the control group. Both UCLP and BCLP groups had decreased values of mandibular volume compared to the normal occlusion group, while these differences were found to be statistically insignificant (p > 0.05). Co-Go (Beta = 0.420; p = 0.014) and Co-Gn variables (Beta = 0.708; p = 0.045) were positively correlated with mandibular volume, while SNB (Beta = -0.669; p = 0.044) and SN-MP (Beta = -0.358; p = 0.049) variables were negatively correlated (R (2) = 60.3 and p = 0.000). CONCLUSION: Mandibular volume insignificantly differs in cleft patients (p > 0.05), and the variables of Co-Go, Co-Gn, SNB, and SN-MP significantly correlate with the volume. CLINICAL RELEVANCE: This article investigates mandibular volume in patients affected by UCLP and BCLP that has never been investigated in the literature. The present study showed that both UCLP and BCLP groups had insignificantly decreased values of mandibular volume compared to the normal occlusion group.

Microshear bond strength of preheated silorane- and methacrylate-based composite resins to dentin.

The aim of this study was to investigate the effect of preheating on microshear bond strength (MSBS) of silorane and methacrylate-based composite resins to human dentin. The teeth were randomly divided into three main groups: (1) composite resins were heated upto 68 °C; (2) cooled to 4 °C; and (3) control [room temperature (RT)]. Each group was then randomly subdivided into four subgroups according to adhesive system used [Solobond M (Voco), All Bond SE (Bisco), Clearfil SE Bond (CSE) (Kuraray), Silorane adhesive system (SAS) (3M ESPE)]. Resin composite cylinders were formed (0.9 mm diameter × 0.7 mm length) and MSBS of each specimen was tested. The preheated groups exhibited the highest MSBS (p < 0.001) and the groups cooled to 4 °C exhibited the lowest MSBS (p < 0.001). The CSE showed higher MSBS than the other adhesives (p < 0.001). This study concludes that preheating of composite resins may be an alternative way to increase the MSBS of composites on dentin.

Effects of chincup or facemask therapies on the orofacial airway and hyoid position in Class III subjects.

OBJECTIVE: The purpose of this work was to evaluate orofacial airway dimensions and the position of the hyoid bone related to changes induced by facemask therapy (combined with rapid palatal expansion) or by chincup therapy as compared to an untreated Class III control group. METHODS: In all, 67 patients with skeletal Class III malocclusion were divided into a facemask group (n = 25; 15 girls and 10 boys), a chincup group (n = 15; 16 girls and 9 boys), and a control group (n=17; 9 girls and 8 boys). Hard- and soft-tissue parameters were analyzed on lateral cephalograms, which were available for all patients and included a baseline radiograph (T1) obtained before treatment and a follow-up radiograph (T2) taken upon completion of active treatment or, in the control group, after a 6-month interval. Statistical analysis was performed at the p ≤ 0.05 level and included a paired-sample t-test, a generalized linear mixed model (GLMM), and a post hoc Tukey test. RESULTS: In the chincup group, significant changes in the perpendicular distance from the hyoid (H) to the C3-Me line were found compared to the control group (p < 0.05). The facemask group, by contrast, showed significant anteroposterior width increases of the pharynx--as measured at the level of the soft palate (p < 0.001)--as well as significant area increases of the nasopharynx based on its anterior portion (p < 0.001) and on its total area (p < 0.001). Both the chincup and the facemask (combined with rapid palatal expansion) therapies were found to induce clockwise rotational effects on the mandible. CONCLUSION: Orofacial airway dimensions were enlarged significantly by facemask treatment in comparison with both chincup treatment and with the control group.

Maxillary sinus volumes of patients with unilateral cleft lip and palate.

BACKGROUND AND OBJECTIVE: Studies about maxillary sinuses of cleft lip-palate patients have increased since sinusitis is commonly observed in these patients. It is evident that maxillary sinus will be morphologically affected in these patients. And anatomic differences may be a cause or at least a contributor of sinusitis. The aim of this study was to compare maxillary sinus volumes of the non-syndromic patients with unilateral cleft lip-palate and control group by using Cone-Beam computed tomography. METHODS: Tomography scans of 44 unilateral cleft lip-palate patients (18 right and 26 left) with age and gender matched 45 control patients were evaluated for the study. The images used in the study were part of the diagnostic records collected due to dental treatment needs. All tomographs were obtained in supine position by using Cone-Beam computed tomography (NewTom 5G, QR, Verona, Italy). The patient-specific Hounsfield values were set to include the largest amount of voxels in the sinuses volume calculation individually. All data were measured in mm(3). RESULTS: There was no statistically difference between the gender and age distributions of the groups. No statistically significant difference was found on the cleft and non-cleft side, the right and left side of the unilateral cleft lip-palate patients and the control group (P>0.05). For the inter group comparison, mean maxillary sinus volumes volume of unilateral cleft lip-palate patients (9894.55±4171.44mm(3)) was statistically smaller than the control group (11,977.90±4484.93mm(3)) (P<0.05). CONCLUSION: Maxillary sinus volumes were effected negatively in unilateral cleft lip-palate patients when compared with the healthy control group. No difference was found on the cleft, non-cleft side and the right-left side of the unilateral cleft lip-palate patients.

Cone-beam computed tomography evaluation of dentoskeletal changes after asymmetric rapid maxillary expansion.

INTRODUCTION: The aims of this study were to quantitatively evaluate the changes in arch widths and buccolingual inclinations of the posterior teeth after asymmetric rapid maxillary expansion (ARME) and to compare the measurements between the crossbite and the noncrossbite sides with cone-beam computed tomography (CBCT). METHODS: From our clinic archives, we selected the CBCT records of 30 patients with unilateral skeletal crossbite (13 boys, 14.2 ± 1.3 years old; 17 girls, 13.8 ± 1.3 years old) who underwent ARME treatment. A modified acrylic bonded rapid maxillary expansion appliance including an occlusal locking mechanism was used in all patients. CBCT records had been taken before ARME treatment and after a 3-month retention period. Fourteen angular and 80 linear measurements were taken for the maxilla and the mandible. Frontally clipped CBCT images were used for the evaluation. Paired sample and independent sample t tests were used for statistical comparisons. RESULTS: Comparisons of the before-treatment and after-retention measurements showed that the arch widths and buccolingual inclinations of the posterior teeth increased significantly on the crossbite side of the maxilla and on the noncrossbite side of the mandible (P <0.05). Comparison of the 2 sides showed statistically significant differences in both the maxilla and the mandible (P <0.05). CONCLUSIONS: After ARME treatment, the crossbite side of the maxilla and the noncrossbite side of the mandible were more affected than were the opposite sides.

Prevalence of dental anomalies in the permanent dentition of children with Down syndrome.

PURPOSE: The purpose of this study was to evaluate the prevalence of various congenital dental anomalies in the permanent dentition of Turkish children with Down syndrome. METHODS: The sample consisted of 216 diagnostic records of children diagnosed with Down syndrome. All subjects had a clinical examination as well as radiographs and photographs taken. Anomalies in the permanent dentition were documented. RESULTS: There was a high incidence of dental anomalies, the most frequent being taurodontism (81 percent), rotation (28 percent), hypodontia (26 percent), tooth impaction (18 percent), ectopic eruption (14 percent), microdontia (13 percent), and hyperdontia (9 percent). Differences in prevalence of congenitally missing teeth, structural anomalies, and positional anomalies reached a statistically significant level regarding gender (P<.05). CONCLUSION: Turkish children with Down syndrome presented a high incidence of anomalies affecting the permanent dentition, and, in most cases, individuals presented with more than one anomaly.

Three-dimensional evaluation of the mandibular third molars' development in unilateral crossbite patients: A cone beam computed tomography study.

OBJECTIVES: The aim was to investigate mandibular third molar (3M)'s maturation in the crossbite and normal sides by two- and three-dimensional analyses using cone beam computed tomography (CBCT). MATERIALS AND METHODS: A retrospective study was performed using CBCT of 25 patients (16 females and 9 males; mean age: 16.8 ± 2.9 years) with unilateral posterior crossbite. The formation stages and the volume of the mandibular 3Ms were evaluated by means of CBCT data of the patients without knowing the crossbite side of the patients. RESULTS: Statistically no significant differences were found in the development of the 3Ms between the crossbite and the control sides, whereas the volume of 3M was found to be less in the crossbite side than in the normal side (P = 0.021). CONCLUSIONS: A volume of 3M was found to be less in the crossbite side than in the normal side.

Three-dimensional evaluation of the pharyngeal airway volumes in patients affected by unilateral cleft lip and palate.

INTRODUCTION: Patients affected by cleft lip and palate often have complaints of snoring and respiratory difficulties during sleep. The purposes of this study were to evaluate nasopharyngeal, oropharyngeal, and total airway volumes of patients affected by unilateral cleft lip and palate and to compare them with a well-matched control group without unilateral cleft lip and palate using cone-beam computed tomography. METHODS: The study sample consisted of 60 patients (26 girls, 34 boys) divided into 2 groups: unilateral cleft lip and palate (20 boys, 10 girls; 8 right sided, 22 left sided; mean age, 14.6 ± 3.2 years) and no cleft (control group; 14 boys, 16 girls; mean age, 14.8 ± 2.8 years). Nasopharyngeal, oropharyngeal, and total airway volumes of the subjects in both groups were calculated 3 dimensionally with cone-beam computed tomography. Group differences in relation to cleft side, sex, and cleft presence were statistically tested at P <0.05. RESULTS: Patients affected by unilateral cleft lip and palate had similar airway volumes regardless of the side of the cleft. In addition, no statistically significant differences were found between the sexes in the 2 groups. Patients affected by unilateral cleft lip and palate had smaller nasopharyngeal, oropharyngeal, and total airway volumes when compared with the control group. The difference for oropharyngeal airway volume (-4036.7 mm(3)) was statistically significant (P <0.05), whereas nasopharyngeal volume (-21.6 mm(3)) and total airway volume (-4057.3 mm(3)) differences were not significant (P >0.05). CONCLUSIONS: Patients affected by unilateral cleft lip and palate had decreased volumes of oropharyngeal (P <0.05) and total (P >0.05) airways compared with the well-matched control group without unilateral cleft lip and palate.

OPG and RANKL levels around miniscrew implants during orthodontic tooth movement.

INTRODUCTION: The aim of this study was to determine the peri-miniscrew implant crevicular fluid receptor activator of nuclear factor-кB ligand (RANKL) and osteoprotegerin (OPG) levels around loaded and unloaded miniscrew implants at different time intervals. METHODS: Twenty loaded and 16 unloaded miniscrew implants were included in this study. All miniscrew implants were placed bilaterally between the maxillary second premolars and first molars as anchorage units for canine distalization. Peri-miniscrew implant crevicular fluid was taken from the mesiobuccal aspects of the loaded and unloaded miniscrew implants before loading; at 24, 48, and 168 hours; and on day 30 after force application. Enzyme-linked immunosorbent assay kits were used to determine RANKL and OPG levels in the peri-miniscrew implant crevicular fluid samples. Wilcoxon, Mann-Whitney U, and Spearman correlation tests were used for statistical evaluations at the P <0.05 level. RESULTS: Although the total amount of OPG was not different between the groups, the total amount of RANKL was significantly elevated in the loaded miniscrew implant group (P <0.05) at all time periods. Peri-miniscrew implant crevicular fluid volume was the highest at 48 hours in the loaded group. Also, the OPG/RANKL ratio in the peri-miniscrew implant crevicular fluid was significantly decreased in the loaded miniscrew implant group. CONCLUSIONS: The OPG and RANKL levels vary around loaded and unloaded miniscrew implants as a result of force application.

Alveolar bone thickness and lower incisor position in skeletal Class I and Class II malocclusions assessed with cone-beam computed tomography.

OBJECTIVE: To evaluate lower incisor position and bony support between patients with Class II average- and high-angle malocclusions and compare with the patients presenting Class I malocclusions. METHODS: CBCT records of 79 patients were divided into 2 groups according to sagittal jaw relationships: Class I and II. Each group was further divided into average- and high-angle subgroups. Six angular and 6 linear measurements were performed. Independent samples t-test, Kruskal-Wallis, and Dunn post-hoc tests were performed for statistical comparisons. RESULTS: Labial alveolar bone thickness was significantly higher in Class I group compared to Class II group (p = 0.003). Lingual alveolar bone angle (p = 0.004), lower incisor protrusion (p = 0.007) and proclination (p = 0.046) were greatest in Class II average-angle patients. Spongious bone was thinner (p = 0.016) and root apex was closer to the labial cortex in high-angle subgroups when compared to the Class II average-angle subgroup (p = 0.004). CONCLUSIONS: Mandibular anterior bony support and lower incisor position were different between average- and high-angle Class II patients. Clinicians should be aware that the range of lower incisor movement in high-angle Class II patients is limited compared to average- angle Class II patients.

Cone-beam computed tomography evaluation of relationship between tongue volume and lower incisor irregularity.

The aim of this study was to evaluate the relationship between the tongue volume and lower incisor irregularity, using cone-beam computed tomography (CBCT), and to identify the possible gender differences. CBCT images of 60 patients between 16 and 36 years of age were selected from 1400 sets of images in the database. Tomography was carried out using iCAT® (Imaging Sciences International, Hatfield, Pennsylvania, USA) and segmentation was carried out by using Mimics 10.1 software (Materialise NV, Leuven, Belgium). The tongue volume was calculated by using the volume of the voxels from the scan and the number of voxels selected for a given mask. Lower incisor crowding was measured with the Little's irregularity index and divided into three groups: mild, moderate, and severe. Independent samples t-test, analysis of variance (ANOVA), and Tukey test were used at P < 0.05 level. Pearson correlation coefficients and linear regression model were calculated to determine the correlation between tongue volume and incisor irregularity. No significant gender dimorphism was found for the tongue volume (females: 28.13 ± 8.54 cm(3) and males: 31.02 ± 9.75 cm(3)). According to ANOVA, there was statistically significant difference in the tongue volume measurements among subjects with different levels of irregularity. Tukey analysis indicated that mild irregularity group (33.97 cm(3)) showed higher values for tongue volume than severe irregularity group (26.60 cm(3); P = 0.025). The relationship between incisor irregularity and tongue volume was evaluated for both genders and significant inverse correlation (r = -0.429; P = 0.029) was determined between lower incisor irregularity and tongue volume in males. In female group, no significant correlation was determined between tongue volume and incisor irregularity.

Solitary median maxillary central incisor: a report of 2 cases.

A single median maxillary central incisor (SMMCI) is a rare dental anomaly that may occur alone or be associated with growth deficiency or other systemic abnormalities. The best known association is with holoprosencephaly (HPE). HPE is a complex brain malformation that affects both the forebrain and the face. Early diagnosis of SMMCI is important, since it may be a sign of other severe congenital or developmental abnormalities. Therefore, systematic follow-up and close monitoring of the growth and development of SMMCI patients is crucial. The purpose of this paper was to report the cases of 2 children, each with a single median maxillary central incisor, and describe important symptoms of this syndrome that have not yet been reported.

Dehiscence and fenestration in patients with different vertical growth patterns assessed with cone-beam computed tomography.

OBJECTIVE: To test the null hypothesis that the presence of alveolar defects (dehiscence and fenestration) was not different among patients with different vertical growth patterns. MATERIALS AND METHODS: A total of 1872 teeth in 26 hyper-divergent (mean age: 24.4 ± 4.8 years), 27 hypo-divergent (mean age: 25.1 ± 4.5 years), and 25 normo-divergent (mean age: 23.6 ± 4.1 years) patients with no previous orthodontic treatment were evaluated using cone-beam computed tomography. Axial and cross-sectional views were evaluated with regard to whether dehiscence and/or fenestration on buccal and lingual surfaces existed or not. For statistical analysis, the Pearson chi-square test was used at a P < .05 significance level. RESULTS: According to the statistical analysis, the hypo-divergent group (6.56%) had lower dehiscence prevalence than the hyper-divergent (8.35%) and normo-divergent (8.18%) groups (P  =  .004). Higher prevalences of dehiscence and fenestration were found on buccal sides in all vertical growth patterns. While fenestration was a common finding for the maxillary alveolar region, dehiscence was a common finding in the mandible in all groups. CONCLUSION: The null hypothesis was rejected. Although the prevalence of fenestrations was not different, significant differences for dehiscences were found in patients with different vertical growth patterns.

Comparison of craniofacial morphology, head posture and hyoid bone position with different breathing patterns.

OBJECTIVES: The aim of this study was to evaluate differences in craniofacial morphology, head posture and hyoid bone position between mouth breathing (MB) and nasal breathing (NB) patients. METHODS: Mouth breathing patients comprised 34 skeletal Class I subjects with a mean age of 12.8 ± 1.5 years (range: 12.0-15.2 years). Thirty-two subjects with skeletal Class I relationship were included in the NB group (mean 13.5 ± 1.3 years; range: 12.2-14.8 years). Twenty-seven measurements (15 angular and 12 linear) were used for the craniofacial analysis. Additionally, 12 measurements were evaluated for head posture (eight measurements) and hyoid bone position (four measurements). Student's t-test was used for the statistical analysis. Probability values <0.05 were accepted as significant. RESULTS: Statistical comparisons showed that sagittal measurements including SNA (p < 0.01), ANB (p < 0.01), A to N perp (p < 0.05), convexity (p < 0.05), IMPA (p < 0.05) and overbite (p < 0.05) measurements were found to be lower in MB patients compared to NB. Vertical measurements including SN-MP (p < 0.01) and PP-GoGn (p < 0.01), S-N (p <0.05) and anterior facial height (p < 0.05) were significantly higher in MB patients, while the odontoid proses and palatal plane angle (OPT-PP) was greater and true vertical line and palatal plane angle (Vert-PP) was smaller in MB patients compared to NB group (p < 0.05 for both). No statistically significant differences were found regarding the hyoid bone position between both groups. CONCLUSIONS: The maxilla was more retrognathic in MB patients. Additionally, the palatal plane had a posterior rotation in MB patients. However, no significant differences were found in the hyoid bone position between MB and NB patients.

Dehiscence and fenestration in skeletal Class I, II, and III malocclusions assessed with cone-beam computed tomography.

OBJECTIVE: To test the null hypothesis that the presence of dehiscence and fenestration was not different among patients with skeletal Class I, II, and III malocclusions. MATERIALS AND METHODS: In this retrospective study, a total of 123 cone-beam computed tomography (CBCT) images were obtained with an iCAT scanner (Imaging Sciences International, Hatfield, Pa). Patients with normal vertical patterns were classified according to dental malocclusion and ANB angle. Class I comprised 41 patients-21 girls and 20 boys (mean age, 22.4 ± 4.5 years); Class II comprised 42 patients-22 girls and 20 boys (mean age, 21.5 ± 4.2 years); and Class III comprised 40 subjects-22 girls and 18 boys (mean age, 22.1 ± 4.5 years). A total of 3444 teeth were evaluated. Analysis of variance and Tukey's test were used for statistical comparisons at the P < .05 level. RESULTS: Statistical analysis indicated that the Class II group had a greater prevalence of fenestration than the other groups (P < .001). No difference was found in the prevalence of dehiscence among the three groups. Although fenestration had greater prevalence in the maxilla, more dehiscence was found in the mandible for all groups. In Class I, alveolar defects (dehiscence, fenestration) were matched relatively in both jaws. Furthermore, Class II and Class III subjects had more alveolar defects (41.11% and 45.02%, respectively) in the mandible. Dehiscences were seen with greater frequency in the mandibular incisors of all groups. CONCLUSION: The null hypothesis was rejected. Significant differences in the presence of fenestration were found among subjects with skeletal Class I, Class II, and Class III malocclusions. Fenestrations had greater prevalence in the maxilla, but more dehiscences were found in the mandible.

Mandibular asymmetry in unilateral and bilateral posterior crossbite patients using cone-beam computed tomography.

OBJECTIVE: To test the hypotheses that (1) there is no difference in mandibular asymmetry between the crossbite and normal side in a unilateral crossbite group (UCG) and between the right and left sides in a bilateral crossbite group (BCG) and a control group (CG); and (2) there is no significant difference in mandibular asymmetry among crossbite groups and control group. MATERIALS AND METHODS: The cone-beam computed tomography scans of three groups were studied: (1) 15 patients (6 male, 9 female; mean age: 13.51 ± 2.03 years) with unilateral posterior crossbite; (2) 15 patients (8 male, 7 female; mean age: 13.36 ± 2.12 years) with bilateral posterior crossbite; and (3) 15 patients (8 male, 7 female; mean age: 13.46 ± 1.53 years) as a control group. Fourteen parameters (eight linear, three surface, and three volumetric) were measured. Side comparisons were analyzed with paired samples t-test, and for the intergroup comparison, analysis of variance (ANOVA) and Tukey tests were used at the P < .05 level. RESULTS: According to side comparisons, no statistically significant difference was found in the UCG. There were statistically significant differences in hemimandibular (P = .008) and ramal (P = .004) volumes for the BCG and in ramal height (P = .024) and body length (P = .021) for the CG. Intergroup comparisons revealed significant differences in hemimandibular (P = .002) and body volume (P < .001) for the normal side of the UCG and left sides of the other groups, and in angular unit length (P = .025) and condylar width (P = .007) for the crossbite side of the UCG and the right sides of the other groups. CONCLUSIONS: Contrary to UCG, CG and BCG were found to have side-specific asymmetry. Skeletal components of the mandible have significant asymmetry among the crossbite groups and the CG.

Orofacial airway dimensions in subjects with Class I malocclusion and different growth patterns.

OBJECTIVE: To test the null hypotheses that there are no significant differences in craniofacial structures and orofacial airway dimensions in subjects with Class I malocclusion and different growth patterns. MATERIALS AND METHODS: Lateral cephalometric radiographs of 31 low angle (mean age, 14.0 ± 2.0 years; range, 10.3-16.5 years), 40 high angle (mean age, 12.7 ± 1.6 years; range, 10.1-16.2 years), and 33 normal growth (mean age, 13.9 ± 1.3 years; range, 11.2-16.8 years) subjects with Class I malocclusion were examined. In total, 34 measurements (27 craniofacial and 7 orofacial airways) were evaluated. Groups were constituted according to the SN-MP angle. Group differences were analyzed with analysis of variance (ANOVA) and the Tukey test, at the P < .05 level. RESULTS: According to ANOVA, only 5 of the 27 craniofacial measurements showed no statistically significant differences among different growth patterns. For orofacial airway measurements, statistically significant differences were found in nasopharyngeal airway space (P < .01), palatal tongue space (P < .05), upper posterior airway space (PAS) (P < .05), and tongue gap (P < .001). No statistically significant orofacial airway differences were determined between low angle and normal growth subjects. High angle subjects had a larger tongue gap than those with normal and low angles (P < .01). Additionally, nasopharyngeal airway space (P < .01) and upper PAS (P < .05) measurements were larger and palatal tongue space (P < .05) was narrower in low angle than in high angle subjects. CONCLUSIONS: The null hypotheses were rejected. Significant differences in craniofacial morphology and orofacial airway dimensions of Class I subjects with different growth patterns were identified.

Bond strengths of an antibacterial monomer-containing adhesive system applied with and without acid etching for lingual retainer bonding.

The aim of this study was to test the null hypothesis that there is no significant difference in bond strength and failure site location of composite bonded to etched and unetched enamel with an antibacterial monomer-containing adhesive and a conventional lingual retainer adhesive system. The crowns of 60 extracted lower human incisors were mounted in acrylic resin leaving the lingual surface of the crowns parallel to the base of the moulds. The teeth were randomly divided into three equal groups: two experimental and a control. Conventional lingual retainer composite (Transbond LR) and antibacterial monomer-containing adhesive (Clearfil Protect Bond), with or without prior etching, were applied to the lingual surface of the teeth by packing the material into cylindrical plastic matrices (Ultradent) with an internal diameter of 2.34 mm and a height of 3 mm to simulate lingual retainer bonding. The shear bond data were analysed using analysis of variance and Tukey's tests. Fracture modes were analysed by chi-square test. Statistical analysis showed that the bond strengths of the control (Transbond LR, mean: 24.77 +/- 9.25 MPa) and Clearfil Protect Bond with etching, (mean: 20.24 +/- 8.5 MPa) were significantly higher than Clearfil Protect Bond without etching, (mean: 12.56 +/- 6.93 MPa). In general, a greater percentage of the fractures were adhesive, at the tooth-composite interface (60-65 per cent). No statistically significant difference was found among the groups. The hypothesis is thus rejected. Within the limits of this in vitro model, antibacterial monomer-containing self-etch adhesive with acid etching did not significantly affect shear bond strength when compared with the control. However, the same adhesive used without acid etching resulted in a significant decrease in bond strength.