Friction versus frictionless mechanics during maxillary en-masse retraction in adult patients with Class I bimaxillary dentoalveolar protrusion: a randomized clinical trial.

BACKGROUND: Extraction space closure is a challenging phase during orthodontic treatment that affects not only the total treatment duration but also the whole treatment outcome. OBJECTIVE: To compare the efficiency of friction and frictionless mechanics during en-masse retraction of maxillary anterior teeth in adult patients with bimaxillary dentoalveolar protrusion. TRIAL DESIGN: Two-arm parallel group, single-center randomized clinical trial. MATERIALS AND METHODS: Thirty-two adult patients with bimaxillary protrusion were recruited and randomly allocated to two different retraction mechanics. A friction group, using NiTi coil springs and a frictionless group using closing T-loops for en-masse retraction. Randomization in a 1:1 ratio was generated by Microsoft Excel. The randomization numbers were secured in opaque sealed envelopes for allocation concealment. Retraction started in all patients following first premolars extraction using miniscrews as a source of indirect anchorage. Activation was done on a monthly basis until complete retraction of anterior segment. The rate of retraction, amount of anchorage loss, the dental, and soft tissue changes were analyzed on digital models and lateral cephalograms taken before retraction and after space closure. BLINDING: The outcome assessor was blinded through data concealment during assessment. RESULTS: Two patients were lost to follow up, so 30 patients completed the trial. The rate of anterior segment retraction was 0.88 ±â€…0.66 mm/month in the frictionless group compared to 0.72 ±â€…0.36 mm/month in the friction group which was statistically significant. Anchorage loss of 1.18 ±â€…0.72 mm in the friction group compared to 1.29 ±â€…0.55 mm in the frictionless group with no significant difference. Comparable dental and soft tissue changes following en-masse retraction were reported in both groups, with no statistically significant difference. HARM: one patient complained of soft tissue swelling following miniscrew insertion, but the swelling disappeared after one week of using mouth wash. LIMITATION: The study focused only on the maxillary arch. CONCLUSION: Both mechanics have successfully achieved the required treatment objectives in patients with bimaxillary dentoalveolar protrusion. Frictionless group showed a faster rate of retraction than the friction group, which was statistically but not clinically significant. TRIAL REGISTRATION: Clinicaltrials.gov with the identifier NCT03261024.

Morphometric analysis of sella turcica in growing patients: an observational study on shape and dimensions in different sagittal craniofacial patterns.

The aim of this study was to evaluate the differences in sella dimensions and shape between growing patients with Class I, Class II, and Class III skeletal malocclusions, evaluated through morphometric analysis. Seventy-eight subjects aged between 9 and 13 years were selected and assigned to either the Class I, Class II, or Class III groups according to the measured ANB angle (the angle between the Nasion, skeletal A-point and skeletal B-point). Six landmarks were digitised to outline the shape of the sella turcica. Linear measurements of the sella length and depth were also performed. Procrustes superimposition, principal component analysis, and canonical variate analysis were used to evaluate the differences in sella shape between the three groups. A one-way MANOVA and Tukey's or Games-Howell tests were used to evaluate the presence of differences in sella dimensions between the three groups, gender, and age. The canonical variate analysis revealed a statistically significant difference in sella shape between the Class I and the Class II groups, mostly explained by the CV1 axis and related to the posterior clinoidal process and the floor of the sella. No differences were found regarding linear measurements, except between subjects with different age. These differences in sella shape, that are present in the earlier developmental stages, could be used as a predictor of facial growth, but further studies are needed.

Occlusal traits of 4-5-year-old Estonians. Parents' perception of orthodontic treatment need and satisfaction with dental appearance.

This study aims to evaluate the prevalence of occlusal traits and to assess parents'/caregivers' satisfaction with child's dental appearance and perception of orthodontic treatment need in 4-5-year-old Estonians. Clinical records and plaster casts of 390 children (190 girls and 200 boys, mean age 4.7 years, range 4 - 5 years) were analyzed. Assessed occlusal traits included deciduous canine and second molar sagittal relationship, overjet, overbite, crowding, midline diastema, crossbite, and scissor bite. Parents'/caregivers' opinions regarding their child's teeth were determined with a questionnaire. The most prevalent occlusal traits were symmetrical sagittal relationship in deciduous canines (78.2%) and molars (75.1%), Class I sagittal relationship in deciduous canines (69.7%) and midline diastema (67.7%). Asymmetrical sagittal canine relationship was registered in 21.8% deciduous canines and in 24.9% second deciduous molars. Parents'/caregivers' perceived orthodontic treatment need was related to Class III sagittal relationship in canines, increased overjet and overbite, negative overbite, and crossbite. Prevalence of most occlusal traits in Estonian children were in line with those reported in neighboring countries. Parents/caregivers were well able to observe occlusal traits that deviated from acceptable occlusion.

[Effect of incisor retraction on three-dimensional morphology of upper airway and fluid dynamics in adult class â patients with bimaxillary protrusion].

Objective: To investigate the effect of incisor retraction on three-dimensional morphology of upper airway and fluid dynamics in class Ⅰ adult patients with bimaxillary protrusion. Methods: Thirty class Ⅰ patients with bimaxillary protrusion that received fixed orthodontic treatment in Department of Stomatology, The First Affiliated Hospital of Wenzhou Medical University from January 2011 to September 2014 were selected using random number table. All the patients were treated with extraction of four first premolars and retraction of anterior teeth using implant anchorage. Cone-beam CT (CBCT) scans were performed before and after incisor retraction for all patients. The CBCT data of the upper airway were constructed using Mimics 16.0, and the flow field characteristics inside the upper airway were simulated using Ansys 14.0. The changes of volume (V), mean cross-sectional area (mCSA), maximum lateral diameters/maximum anteroposterior diameters (LP/AP) of cross section, the maximum pressure of airflow (P(max)), the minimum pressure of airflow (P(min)) and pressure drop (△P) of nasopharynx, oropharynx and hypopharynx before and after incisor retraction were measured and compared using paired t test. The correlation between the variation of △P in the most significant pharyngeal part and the morphological variables after incisor retraction was analyzed using Pearson correlation test. Results: No statistical differences were observed in the morphology and flow field in nasopharynx before and after incisor retraction (P>0.05). Before incisor retraction, the oropharyngeal volume and mCSA were (7 580±622) mm(3) and (217±40) mm(2), respectively, and the hypopharyngeal volume and mCSA were (2 564±162) mm(3), and (239±43) mm(2), respectively. After incisor retraction, the volumes of oropharynx and hypopharynx were (6 885±601) mm(3) and (2 535±156) mm(3), respectively, and mCSA of oropharynx and hypopharynx were (197±37) mm(2) and (236±42) mm(2), respectively. The volume and mCSA of oropharynx and hypopharynx were significantly decreased after incisor retraction (P<0.05). The greatest changes in pharyngeal volume and mCSA occurred in the oropharynx. In addition, the LP/AP of oropharynx after incisor retraction was changed from 1.9±0.6 to 2.1±0.7, which was significantly increased compared with the levels before incisor retraction (P<0.05). After simulation of pharyngeal airflow, the oropharyngeal P(min), hypopharyngeal P(max) and P(min) were (-13.7±4.3), (-8.3±3.8) and (-42.8±9.5) Pa, respectively, whereas the values turned to (-16.4±6.5), (-11.9±3.6) and (-46.0±11.0) Pa, respectively after incisor retraction, which was significantly reduced (P<0.05). △P of oropharynx was significantly increased from (42.7±10.1) Pa to (45.2±13.0) Pa after incisor retraction (P<0.05) and the variation of oropharyngeal △P was negatively correlated with the variation of V and mCSA in oropharynx before and after incisor retraction (r=-0.681, P=0.001; r=-0.844, P=0.000). Conclusions: The oropharynx was constricted and the pharyngeal resistance was increased after incisor retraction in adult class Ⅰ patients with bimaxillary protrusion. A comprehensive and systematic evaluation of the pharyngeal morphology and ventilatory function were very important for making a scientific and rational clinical treatment plan.

Root resorption due to orthodontic treatment using self-ligating and conventional brackets : A cone-beam computed tomography study.

OBJECTIVES: Purpose of the present study was to compare external root resorption (ERR) volumetrically in maxillary incisors induced by orthodontic treatment using self-ligating brackets (Damon Q, DQ) or conventional brackets (Titanium Orthos, TO) with the help of cone-beam computed tomography (CBCT). PATIENTS AND METHODS: A sample of 32 subjects, with Angle Class I malocclusion and anterior crowding of 4-10 mm, was divided randomly into two groups: a DQ group, in which self-ligating DQ brackets with Damon archwires were used; and a TO group, in which conventional TO brackets with large Orthos archwires were applied. The study was conducted using CBCT scans taken before (T1), and near the end (9 months after the initiation of treatment; T2) of the orthodontic treatment. The extent of ERR was determined volumetrically using Mimics software. Changes in root volume were evaluated by repeated-measures analysis of variance as well as by paired and independent t-tests. RESULTS: While significant differences were found between T1 and T2 for root volume in both groups (p < 0.05), there was no difference between the groups regarding the amount (mm3 or relative change) of ERR (p > 0.05). Maxillary central and lateral incisors showed similar volume loss (p > 0.05). Furthermore, the TO group showed a higher prevalence of palatinal and proximal slanted RR compared with the DQ group (p < 0.05). CONCLUSIONS: It is not possible to suggest superiority of one bracket system over the other only considering root resorption pattern or amount. Higher incidence of slanted RR found in patients treated with the TO system warrants further research to identify possible specific causes.

The electrical activity of the masticatory muscles in children with cleft lip and palate.

BACKGROUND: Information regarding masticatory muscle function in children with cleft lip and palate (CLP) is limited. As a consequence, research on masticatory muscle activity in cleft subjects is needed. AIM: To assess masticatory muscle activity in children surgically treated for CLP as well as identify the possible factors associated with this activity. DESIGN: The sample comprised 82 children with mixed dentition and Class I occlusions (25 children with unilateral CLP and 57 subjects with no cleft abnormalities). A DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) was used to take electromyographical (EMG) recordings of the temporal and masseter muscles both in the mandibular rest position and during maximum voluntary contraction (MVC). RESULTS: Patients with clefts showed a significant increase in temporal muscle activity at rest compared with the controls. The presence of clefts and unilateral posterior crossbites are factors strongly associated with increased temporal muscle EMG potentials during rest position. CONCLUSIONS: Children with clefts have altered temporal muscle function. The presence of posterior crossbites affects the temporal muscle activity in cleft subjects. Early diagnosis and orthodontic treatment of malocclusions are necessary to achieve functional improvement in these patients.

Three-dimensional mandibular motion in skeletal Class III patients.

OBJECTIVE: The aim of the study was to analyze the characteristics and changes in mandibular condylar motion in patients with skeletal Class III malocclusion. METHODS: Using a 3D motion analyzer, mandibular movements were recorded in 9 patients with skeletal Class III malocclusion and 22 control subjects with Angle Class I jaw relationships. RESULTS: Class III patients had a similar interincisor point displacement but a significantly reduced displacement of both condyles on the sagittal and frontal planes, with smaller translation paths than control subjects (right -9.4 mm; left -4.8 mm). The overall condylar rotation component was larger in Class III patients (right +8.8%; left +7.3%). The largest inter-group significant differences were observed in the first 10% of mouth opening, in which Class III patients had a larger rotating component than control subjects (+20%, p < 0.01). CONCLUSIONS: Condylar motion was reduced in skeletal Class III patients, in particular in the translational path.

Evaluation of lip force in patients with unilateral and bilateral cleft lip.

Our aim was to investigate the differences in the dynamics of lip force between a group of participants with repaired cleft lips and a group of patients the same age but without clefts. We evaluated 101 children between the ages of 10 to 15 years (unilateral clefts n=35, bilateral clefts n=15, class I malocclusion n=25, and class III malocclusion n=26). Maximum and minimum forces required to close the lips were evaluated with the Lip De Cum® device (Cosmos Instruments Co Ltd, Tokyo, Japan) for the all groups. We found no significant differences between the maximum and minimum values between boys and girls within the groups, whereas the mean maximum and minimum lip force of the boys was higher than those of the girls in all the groups. This study showed that maximum and minimum lip closing force values were statistically similar in all groups. We conclude, therefore, that patients with bilateral cleft lip have reduced maximum and minimum lip force.

The relationship between lip-closing force and dental arch morphology in patient with Angle Class I malocclusion.

Dental arch morphology and tooth position are affected by lip-closing force (LCF). This study aimed to quantitatively evaluate the relationships between the horizontal or vertical balance of the LCF generated during maximum voluntary pursing-like movements and dental arch length (DAL) or width (DAW) or the lingual inclination of the upper or lower 1st molars (LIUM, LILM) in patients with Angle Class I malocclusion. Sixteen subjects with Angle Class I malocclusion (median age: 23·4 ± 5·9 years) who had never undergone orthodontic treatment were randomly selected. LCF was measured in eight directions during maximum voluntary pursing-like lip-closing movements. Dental arch models were scanned and analysed to obtain DAW, DAL, LIUM and LILM measurements. Mandibular deviation was measured on posteroanterior cephalograms. A significant negative correlation was detected between maxillary DAL and upper LCF. Maxillary DAL, DAW and the DAL/DAW ratio displayed significant negative correlations with total LCF and upper LCF. However, no significant correlations were detected between any mandibular dental arch morphological parameter and LCF. The difference in the LIUM between the deviation and non-deviation sides exhibited a significant positive correlation with the difference in upper LCF between the deviation and non-deviation sides and was significantly negatively correlated with the difference in lower LCF between the deviation and non-deviation sides. These results suggest that upper LCF is related to maxillary DAL, and the horizontal balance of the LCF of the upper and lower lips is related to the LIUM during pursing-like lip-closing movements in patients with Angle Class I malocclusion.

The influence of occlusal morphology on occlusion time.

OBJECTIVES: The aim of the study was to assess how the morphology of the occlusal surfaces of premolars and molars influenced the occlusion time in a mixed gender group of young adults with full natural dentition. METHODS: Fifty healthy volunteers with Angle's Class I occlusion were included in the study. After clinical examination, the alginate impressions of both arches were taken, and plaster casts were prepared. To assess the morphology of lateral teeth, the digital models were measured. Occlusal analysis was performed with the T-Scan® III to assess occlusion time. RESULTS: A direct correlation was found between the cusp distance for the first upper premolar and occlusion time (r = -0.29, p<0.05) and the distance between distal buccal and distal lingual cusps of the first lower premolar and occlusion time (r = 0.33, p<0.05). The parameters that had their impact on occlusion time were the opening angle of lingual cusps for the lower molars and the furrow angle of aperture between cusps for first upper premolar. DISCUSSION: Occlusal surface morphologies of premolars may have direct impact on occlusion time. However, anterior guidance parameters and morphologies of molars could also influence the time teeth are in contact coming to maximal intercuspation.

Establishing the Cephalometric Values for Tetragon Analysis in Patients with Class I Occlusion: A Cephalometric Study.

OBJECTIVES: Proper application of the cephalometric norms for tetragon analysis for better understanding, diagnosis, and management of dentofacial deformities in the ethnic population. MATERIALS AND METHODS: A total of 204 subjects, inclusive of males (102) and females (102), were selected randomly from the outpatient department of Saveetha Dental College and Hospitals, in the age group ranging from 18 to 25 years, fulfilling the inclusion criteria. Assessment of each lateral cephalogram was done using tetragon analysis to evaluate the cephalometric values for individuals with class I occlusion using the FACAD(®) 3.4.0.3 A software. RESULTS: Statistically significant differences were found for all parameters between the ethnic population and the Caucasian norms. Four out of 14 parameters were found to be significantly different between male and female in the ethnic population. CONCLUSION: This study indicates that the local ethnic population have more prognathic maxillary and mandibular jaws, converging tendency of the jaw bases (resulting in reduced lower anterior facial height and horizontal growth pattern) as indicated by the analysis done in the tetragon and the trigon, and increased proclination of the upper and lower incisors.

Long-term outcomes of mandibular kinematics following class II malocclusion therapy with removable functional appliance therapy.

OBJECTIVE: To evaluate mandibular kinematics in class I adults following class II therapy with removable functional appliances (RFAs) during the growth period in comparison with orthodontically untreated class I and II individuals. METHODS: Condylar (CRoM) and incisal range of motion (InRoM), velocity during opening and closing, and the mandibular rotation angle were recorded using an ultrasound-based jaw-tracking system in 36 test patients (mean age = 28.03 ± 6.58 years). RESULTS: Significant group effects were found for CRoM towards the posterior in the right joint (p = 0.002) and InRoM towards the anterior (p = 0.043). The post hoc Tukey test indicates a significantly longer CRoM (posterior) for the right condyle in class II (p = 0.003) and RFA individuals (p = 0.023). DISCUSSION: The kinematic data imply greater dentoalveolar effects due to RFA therapy than adaptive remodeling of the temporomandibular joint. The class I relationship in the RFA group following treatment indicates stable long-term outcomes.

Comparison of craniofacial growth of untreated Class I and Class II girls from ages 9 to 18 years: a longitudinal study.

INTRODUCTION: The purposes of this study were to examine and compare the craniofacial growth in girls with Class I or Class II occlusion from the ages of 9 to 18. METHODS: Twenty-five Class I (ANB, 1°-4°) and 21 Class II (ANB, >4°) untreated Caucasian girls were selected from the Burlington Growth Centre in Toronto, Ontario, Canada. Cephalograms of each subject at ages 9, 14, and 18 years were traced, and 29 parameters were measured. The growth changes in each parameter from ages 9 to 14, 14 to 18, and 9 to 18 were calculated, and comparisons of each parameter were made between the 2 groups. RESULTS: From ages 9 to 14, the Class I and Class II groups had similar skeletal growth patterns (increases of SNA and SNB angles, decreases of ANB, MP-SN, and gonial angles). Dentally, the Class II group showed less maxillary incisal proclination and more overbite than did the Class I group. From ages 14 to 18, the 2 groups also showed similar growth patterns, with little sagittal but continued vertical growth, and the MP-SN angle continued to decrease. From ages 9 to 18 (combined periods of 9-14 and 14-18), the 2 groups showed similar skeletal growth, with the exception of a slightly higher ANS-ME/N-Me in the Class I group. Dental changes were similar in the 2 groups, except that overbite increased slightly more in the Class II group. CONCLUSIONS: Overall, the craniofacial growth patterns of Class I and Class II girls were similar. With growth, the face became more flattened with a decrease of the ANB angle, and the mandible demonstrated forward rotation with decreases of the MP-SN and gonial angles, and an increase of PFH:AFH.

Duration of the peak of adolescent growth spurt in class i and ii malocclusion subjects using a cervical vertebrae maturation analysis.

The aim of the present work was to determine the duration of the adolescent peak growth spurt using cervical vertebral maturation analysis in class I and II malocclusion subjects. The study was conducted on a sample which consisted of 154 lateral cephalograms of children and adolescents aged 9-15 years (84 females and 70 males). The evaluation of skeletal maturation stage was performed using a visual morphological analysis of CS3 and CS4 cervical vertebrae. The sagittal skeletal relation was evaluated according to Steiner analysis. Descriptive statistics were used to summarize chronological age in each malocclusion group and for each CS3 and CS4 skeletal maturation stage. Due to a lack of normal distribution, comparisons of CS3 and CS4 age intervals on class I and II subjects were compared using the Mann-Whitney U test for independent samples. The results show that the mean duration of the adolescent peak growth spurt was 10 months between CS3 and CS4 stages in class I malocclusion subjects, whereas in class II malocclusion patients the duration was 6 months. This difference of 4 months was statistically significant (p<0.001). Finally, a clinically significant difference of 4 months in the duration of the adolescent peak growth spurt for class I and II malocclusion subjects was identified.

The inadequacy of the Y-axis of growth (SNGn) for the vertical pattern assessment in patients with sagittal discrepancies.

AIM: The aim of this cephalometric study was to evaluate the influence of the sagittal skeletal pattern on the 'Y-axis of growth' measurement in patients with different malocclusions. MATERIALS AND METHODS: Lateral head films from 59 patients (mean age 16y 7m, ranging from 11 to 25 years) were selected after a subjective analysis of 1630 cases. Sample was grouped as follows: Group 1 - class I facial pattern; group 2 - class II facial pattern; and Group 3 - class III facial pattern. Two angular measurements, SNGoGn and SNGn, were taken in order to determine skeletal vertical facial pattern. A logistic regression with errors distributed according to a binomial distribution was used to test the influence of the sagittal relationship (Class I, II, III facial patterns) on vertical diagnostic measurement congruence (SNGoGn and SNGn). RESULTS: RESULTS show that the probability of congruence between the patterns SNGn and SNGoGn was relatively high (70%) for group 1, but for groups II (46%) and III (37%) this congruence was relatively low. CONCLUSION: The use of SNGn appears to be inappropriate to determine the vertical facial skeletal pattern of patients, due to Gn point shifting throughout sagittal discrepancies. Clinical Significance: Facial pattern determined by SNGn must be considered carefully, especially when severe sagittal discrepancies are present.

Archform comparisons between skeletal class II and III malocclusions.

The purpose of this cross-sectional research was to explore the relationship of the mandibular dental and basal bone archforms between severe Skeletal Class II (SC2) and Skeletal Class III (SC3) malocclusions. We also compared intercanine and intermolar widths in these two malocclusion types. Thirty-three virtual pretreatment mandibular models (Skeletal Class III group) and Thirty-five Skeletal Class II group pretreatment models were created with a laser scanning system. FA (the midpoint of the facial axis of the clinical crown)and WALA points (the most prominent point on the soft-tissue ridge)were employed to produce dental and basal bone archforms, respectively. Gained scatter diagrams of the samples were processed by nonlinear regression analysis via SPSS 17.0. The mandibular dental and basal bone intercanine and intermolar widths were significantly greater in the Skeletal Class III group compared to the Skeletal Class II group. In both groups, a moderate correlation existed between dental and basal bone arch widths in the canine region, and a high correlation existed between dental and basal bone arch widths in the molar region. The coefficient of correlation of the Skeletal Class III group was greater than the Skeletal Class II group. Fourth degree, even order power functions were used as best-fit functions to fit the scatter plots. The radius of curvature was larger in Skeletal Class III malocclusions compared to Skeletal Class II malocclusions (rWALA3>rWALA2>rFA3>rFA2). In conclusion, mandibular dental and basal intercanine and intermolar widths were significantly different between the two groups. Compared with Skeletal Class II subjects, the mandibular archform was more flat for Skeletal Class III subjects.

The influence of functional therapy on facial and dental structures. Case presentation.

In the era of fixed appliances, some orthodontic practitioners seem to forget about functional therapy. Functional appliances are the only capable of orthopedically changes during the growth spurt. Activators of all types, classic or opened, are elected appliances in growing subjects with class II/1 anomalies. The appropriate case selection, along with patient compliance, lead to improved facial aesthetic and dental occlusion, at affordable prices. With this case presentation, we want to show our protocol in the management of these cases.

Mandibular growth comparisons of Class I and Class II division 1 skeletofacial patterns.

OBJECTIVE: To determine class and sex differences in mandibular growth and modeling. MATERIALS AND METHODS: A mixed-longitudinal sample of 130 untreated French-Canadian adolescents, 77 (45 boys and 32 girls) with Class I (normal or abnormal) occlusion and 53 (26 boys and 27 girls) with Class II division 1 malocclusion, was used. Based on eight landmarks, eight traditional measurements were used to compare the anteroposterior position of the maxilla and mandible, relationship between the jaws, and mandibular size. Mandibular superimpositions were used to compare the horizontal and vertical changes of condylion, gonion, and menton. RESULTS: While there were no differences in maxillary position based on the SNA angle, Class IIs had more retrognathic mandibles than did Class Is. Total mandibular length was greater in Class Is than in Class IIs at 15 years of age. Superior and total growth and modeling changes at condylion and gonion, respectively, were greater for Class Is than Class IIs. Boys were more prognathic than girls; they had larger mandibles and exhibited greater size increases and growth changes than girls did. CONCLUSIONS: There are both class and sex differences in mandibular growth and modeling.