[Comparison of skeletal structure of temporomandibular joint through cone-beam CT between Angle Classâ , â ¡1, â ¡2, â ¢ malocclusion patients with permanent dentition].

PURPOSE: To compare characteristics of temporomandibular joint and related structures according to gender and Angle Ⅰ, Ⅱ1, Ⅱ2 and Ⅲ class. METHODS: Cone-beam CT (CBCT) was performed in 123 patients with malocclusion, and three-dimensional reconstruction was performed with Mimics 19.0 software. The anterior, upper, and posterior spaces of temporomandibular joint, width and depth of acetabulum, height and horizontal angle of condyle, radius of condyle, and anteroposterior and long-axis diameter of condyle were analysed on sagittal plane. The position of condyle in the joint fossa was analyzed using Pullinger methods. SPSS 22.0 software package was used for statistical analysis. RESULTS: Significant differences were found in the long axis and radius of the condyles between Class Ⅰ and Ⅲ, Class Ⅰ and Ⅱ1, respectively (P<0.05). The widest acetabulum was observed in Class Ⅲ, followed by Class Ⅰ, Ⅱ1, and Ⅱ2. Moreover, the deepest acetabulum was found in Class Ⅱ2, followed by Class Ⅱ1, Ⅰ, and Ⅲ. No significant differences were detected in the left and right condyle-related structures among different temporomandibular articulation. In addition, the anterior articular space was significantly larger in Class Ⅰ patients, compared with Class Ⅱ2 patients. CONCLUSIONS: There are significant differences in condylar morphology, joint space, joint fossa morphology and condylar position between different Angle classifications.

[A study on effects of unilateral maxillary canine impaction on the dento-maxillofacial three-dimensional structure].

PURPOSE: To investigate the three-dimensional structure characteristics of unilateral impacted teeth by cone-beam CT (CBCT), and to evaluate the risk factors for upper impacted teeth, so as to provide evidence for early clinical intervention in orthodontics. METHODS: Thirty patients with unilateral maxillary canine impaction were included. Their CBCT images were measured by three-dimensional reconstruction of Romexis software. The differences of the three-dimensional structure characteristics between two sides were measured and compared with SPSS17.0 software package. Paired t test and regression analysis of related data were performed. RESULTS: Significant difference in inclination of both canine and lateral incisor was found between impacted side and normal eruption side, with canine mesially inclined and lateral incisor distally inclined (P<0.001). Volumes of the canines were significantly bigger and those of the lateral incisor were significantly smaller on the impacted side compared with the normal eruption side (P<0.05). The occurrence of impacted canine increased with the increase of the volume of the canine and decrease of the volume of the lateral incisor. Significant difference in arch length and arch width in canine and premolar area was found between impacted side and normal eruption side (P<0.001). There was no significant difference in width in molar area between both sides(P>0.05). There was no significant difference in arch length in canine, premolar and molar region (P>0.05). CONCLUSIONS: Maxillary impacted canines can lead to three-dimensional abnormalities of the ipsilateral teeth and alveolar bone, the severity of maxillary impacted canine is closely related to surrounding dental structural abnormalities, suggesting that maxillary impacted canines can be predicted, early diagnosed, and early effectively intervened as well.

[Features and influence of impacted maxillary permanent canine on surrounding structures].

Impacted maxillary permanent canine is the tooth that most commonly fails to erupt after the third molars. It can probably affect the dental arch alignment and form, occlusal function and facial profile as well. In this review, the epidemiology, etiology and influence on surrounding tissue of the impacted maxillary permanent canine were analyzed based on related literatures with the hope of providing references for clinical practice.

[Torque control evaluated by lateral cephalometric radiography and cone-beam CT after retraction of the upper anterior teeth].

PURPOSE: To investigate the relationship between torque control and movement type of the teeth and to investigate the correlation between reconstruction of the alveolar bone and retraction of the upper anterior teeth. METHODS: Cephalograms of pre-treatment and post-treatment of 111 cases and cone-beam computed tomography of pre-retraction and post-retraction of 7 cases were collected. The inclination degree of the upper anterior teeth, the horizontal and vertical displacement of edge and apex,and the thickness of the alveolar bone at the apex level were measured. Student's t test and Pearson χ2 test were performed for statistical analysis with SAS 8.02 software package. RESULTS: Cases who received torque control during the period of retraction displayed less change of inclination degree of the upper anterior teeth, less lingual displacement of the edge, more lingual displacement of the apex. The total thickness of the alveolar bone at the apex level and the length of the teeth significantly decreased after retraction(P<0.05). The amount of the alveolar bone rebuilt after retraction was less than that of the tooth movement, and there was no significant difference between teenagers and adults. CONCLUSIONS: During retraction of the upper anterior teeth, cases who received torque control showed less inclination degree change of the upper anterior teeth, less lingual displacement of the edge, more lingual displacement of the apex. More bodily movement and partially controlled tipping movement as well as higher incident rate of severe root resorption would also arise. There was correlation between reconstruction of the alveolar bone and the tooth movement. Since the amount of adaptive reconstruction of the lingual alveolar bone was limited, and there was no difference between teenagers and adults, excessive lingual displacement would surpass its adaption ability, and gave rise to alveolar bone and tooth damage.

Bond strength of metal brackets bonded to a silica-based ceramic with light-cured adhesive : Influence of various surface treatment methods.

OBJECTIVE: The purpose of this work was to evaluate the effects of several surface treatment methods on the shear bond strengths of metal brackets bonded to a silica-based ceramic with a light-cured adhesive. MATERIALS AND METHODS: Silica-based ceramic (IPS Classic(®)) with glazed surfaces was cut into discs that were used as substrates. A total of 80 specimens were randomly divided into four groups according to the method used: 9.6 % hydrofluoric acid (group 1), 9.6 % hydrofluoric acid (HF) + silane coupling agent (group 2), sandblasting (aluminum trioxide, 50 µm) + silane (group 3), and tribochemical silica coating (CoJet™ sand, 30 µm) + silane (group 4). Brackets were bonded to the treated specimens with a light-cure adhesive (Transbond XT, 3 M Unitek). Shear bond strength was tested after bracket bonding, and the Adhesive Remnant Index (ARI) scores were quantified after debonding. RESULTS: Group 4 showed the highest bond strength (12.3 ± 1.0 MPa), which was not significantly different from that of group 3 (11.6 ± 1.2 MPa, P > 0.05); however, the bond strength of group 4 was substantially higher than that of group 2 (9.4 ± 1.1 MPa, P < 0.05). The shear bond strength of group 1 (3.1 ± 0.6 MPa, P< 0.05) was significantly lower than that of the other groups. CONCLUSION: Shear bond strengths exceeded the optimal range of ideal bond strength for clinical practice, except for the isolated HF group. HF acid etching followed by silane was the best suited method for bonding on IPS Classic(®). Failure modes in the sandblasting and silica-coating groups revealed signs of damaged ceramic surfaces.

[The relationship between the movement type during retracting the anterior teeth and the external apical root resorption and its evaluation methods].

External apical root resorption was a common phenomenon associated with orthodontic treatment. The reported incidence ranged from 0% to 100%. It was caused by several factors, which could be mainly divided into biological and mechanical aspects. Biological factors included genetic susceptibility, systemic diseases, gender and medication intake. Mechanical factors consisted of the magnitude of orthodontic force, force type and duration, types of tooth movement, as well as excessive tooth movement. This review discussed the relationship between the movement type during retracting the anterior teeth and the external apical root resorption and its evaluation methods.

Shear bond strength of an experimental composite bracket.

OBJECTIVE: The in vitro shear bond strength of MZ100 brackets (an experimental composite bracket developed by the Dental Biomaterial Laboratory at Boston University) and the effect of different treatment methods on these brackets were evaluated. MATERIALS AND METHODS: As the bonding substrates, 80 Vitablocs® Mark II (Vident, Brea, CA, USA) were chosen. Three treatment methods were employed on 60 MZ100 bracket bases (20 brackets per treatment): silane coupling agent (Porcelain Primer; Ormco, Orange, CA, USA), sandblasting (Basic Professional Model Sandblaster; Renfert GmbH, Germany), and non-treatment. Two different orthodontic adhesives were also used: Blugloo™ (Ormco, Orange, CA, USA) and Enlight™ (Ormco, Orange, CA, USA). Twenty metal brackets were used as controls. Shear bond strength tests were performed after sample preparation and bracket bonding. RESULTS: The mean shear bond strength of non-treated MZ100 brackets bonded with Enlight™ had the lowest value (7.9 MPa), while that of sandblasted MZ100 brackets bonded with Blugloo™ showed the highest value (17.9 MPa). The mean shear bond strength of non-treated MZ100 brackets was significantly lower than that of the other groups (p<0.05). The mean shear bond strength of sandblasted MZ100 brackets bonded with Blugloo™ was significantly higher than that of those bonded with Enlight™ (p<0.05). With the exception of the silane-Blugloo™ group, the treated MZ100 brackets demonstrated shear bond strengths that did not significantly differ from metal brackets. CONCLUSION: The use of sandblasting and silane coupling agent significantly increases the shear bond strength of the MZ100 brackets to values resembling those of metal brackets.

Effects of lithium on extraction socket healing in rats assessed with micro-computed tomography.

OBJECTIVE: Lithium is an activator of ß-catenin signaling and ß-catenin plays an important role in regulating bone formation and remodeling. The purpose of this study was to investigate the effects of lithium on bone repair in tooth extraction sockets in rats. MATERIAL AND METHODS: Twenty male Wistar rats were subjected to maxillary left second molar extraction. The animals received a daily injection of lithium chloride (LiCl) or the same dose of sodium chloride (NaCl) starting 7 days before tooth extraction until sacrifice 14 days after extraction. Rats were randomly divided into: (1) a pre-treated group that received LiCl injection from 7 days before to 3 days after tooth extraction; (2) a post-treated group that received LiCl injection starting 4 days after tooth extraction; (3) a continuously treated group that received LiCl injection for the entire 21 days; and (4) a control group that received NaCl injection only. The volume of new bone and the bone density in the extraction socket were quantified by micro-computed tomography. RESULTS: The percentage of new bone formation in the extraction socket was as follows: 63.2 ± 13.4% (pre-treated group), 53.9 ± 9.8% (post-treated), 23.8 ± 8.0% (continuously treated) and 37.5 ± 4.2% (control). The difference in percentage was statistically significant between each pair of groups. Pre- and post-treated groups also showed a significant increase in the density of new bone. CONCLUSIONS: Lithium enhances bone repair in extraction sockets when delivered before or after tooth extraction. Tooth extraction during lithium treatment may impair bone healing.

[Research on Chinese orthodontic specialists' subjective evaluation of orthodontic treatment outcome].

OBJECTIVE: To analyze the results of multiple Chinese orthodontic specialists' subjective evaluation of orthodontic treatment outcome, to investigate the relevance of different experiment items and to explore the weight of each monomial material. METHODS: As a randomized clinical trial, with six orthodontic treatment centers and Angle's classification being regarded as two stratification factors, it contained 108 cases with integrity data, which was random extracted from 2383 cases that received orthodontic treatment in six orthodontic treatment centers during the past five years, gathering post-treatment study casts, cephalometrics and photographs of 48 cases as the research subject. Similarly taking Angle's classification as a stratification factor, 108 cases were randomly divided into 9 groups. The randomization of sampling and grouping were both generated by a pseudo-random number generator. According to the monomial and combined subjects, 69 orthodontic specialists were regarded as the raters to rank the 12 cases in each group, and to judge whether the case was qualified. RESULTS: Correlation analysis: the Spearman r between Post-M + C and Post-M + C + P and the Spearman r between Post-M + P and Post-M + C + P were both greater than 0.950. The Spearman r between Post-M and Post-P and the Spearman r between Post-M and Post-C were about 0.300. The Spearman r between Post-P and Post-C was 0.505. Regression analysis: the linear regression results: M + C = 0.782M + 0.308C - 0.150, M + P = 0.804M + 0.233P - 0.091, M + C + P = 0.764M + 0.243P + 0.131C - 0.291. The r(2) of above three models was greater than 0.9. CONCLUSIONS: It was applicable to use M + C and M + P instead of M + C + P. Study casts could not replace cephalometrics or photographs when doing subjective evaluation. Cephalometrics and photographs could not substitute for each other either. In the combined materials evaluation, model accounted for the largest percentage. Based on the regression model, for the greater part, the integration of several monomial materials could replace the combined material assessment effectively.

Impact of rapid maxillary expansion in unilateral cleft lip and palate patients after secondary alveolar bone grafting: review and case report.

The purpose of this article was to analyze the effects and short-term stability of rapid maxillary expansion performed after secondary alveolar bone grafting in unilateral cleft lip and palate (UCLP) patients. Two UCLP patients with severe maxillary constriction who had previous bone grafting were involved in this study. A hyrax rapid expansion appliance was placed on 4 abutment teeth and activated twice daily. An opening of the midpalatal suture was found on the posttreatment occlusal radiographs, which was clinically confirmed by the diastema. Posteroanterior cephalometric tracing analysis demonstrated significant increases in maxillary and dental arch width. No obvious radiographic alteration was observed in the grafted areas.

[Presurgical alveolar molding using computer aided design in infants with unilateral complete cleft lip and palate].

PURPOSE: To establish a new method of presurgical alveolar molding using computer aided design(CAD) in infants with complete unilateral cleft lip and palate (UCLP). METHODS: Ten infants with complete UCLP were recruited. A maxillary impression was taken at the first examination after birth. The study model was scanned by a non-contact three-dimensional laser scanner and a digital model was constructed and analyzed to simulate the alveolar molding procedure with reverse engineering software (RapidForm 2006). The digital geometrical data were exported to produce a scale model using rapid prototyping technology. The whole set of appliances was fabricated based on these solid models. RESULTS: The digital model could be viewed and measured from any direction by the software. By the end of the NAM treatment before surgical lip repair, the cleft was narrowed and the malformation of alveolar segments was aligned normally, significantly improving nasal symmetry and nostril shape. CONCLUSIONS: Presurgical NAM using CAD could simplify the treatment procedure and estimate the treatment objective, which enabled precise control of the force and direction of the alveolar segments movement.

[Review of the impact of orthodontic treatments on soft tissue profile].

There are some people who have demands on the soft tissue profile among the patients who search for even teeth.On the other hand,when drawing up a plan,orthodontists will consider the soft tissue analysis.This review is focused on the assessment way of soft tissue profile,impact of orthodontic treatments such as functional appliances, extraction treatment, etc on the profile.

[Study on the teaching mode and quality management of orthodontic education in undergraduates].

Orthodontic teaching, especially in undergraduates is the most difficult part in dental education, not only on the aspect of theoretical teaching covering a wide range of disciplines in limited teaching hours, but also their application in clinical practice. With the aim of training qualified dental practitioner with global competitiveness, improving the quality of training curriculum, the Orthodontic Department of Shanghai Jiao Tong University College of Stomatology has persisted in researching and reforming the teaching system. This paper described the current situation of orthodontic teaching and the concept of quality management. Our thought on the teaching mode and quality management of orthodontic training was also discussed.

A novel technique for presurgical nasoalveolar molding using computer-aided reverse engineering and rapid prototyping.

OBJECTIVE: To establish a new method of presurgical nasoalveolar molding (NAM) using computer-aided reverse engineering and rapid prototyping technique in infants with unilateral cleft lip and palate (UCLP). METHODS: Five infants (2 males and 3 females with mean age of 1.2 w) with complete UCLP were recruited. All patients were subjected to NAM before the cleft lip repair. The upper denture casts were recorded using a three-dimensional laser scanner within 2 weeks after birth in UCLP infants. A digital model was constructed and analyzed to simulate the NAM procedure with reverse engineering software. The digital geometrical data were exported to print the solid model with rapid prototyping system. The whole set of appliances was fabricated based on these solid models. RESULTS: Laser scanning and digital model construction simplified the NAM procedure and estimated the treatment objective. The appliances were fabricated based on the rapid prototyping technique, and for each patient, the complete set of appliances could be obtained at one time. By the end of presurgical NAM treatment, the cleft was narrowed, and the malformation of nasoalveolar segments was aligned normally. CONCLUSIONS: We have developed a novel technique of presurgical NAM based on a computer-aided design. The accurate digital denture model of UCLP infants could be obtained with laser scanning. The treatment design and appliance fabrication could be simplified with a computer-aided reverse engineering and rapid prototyping technique.

Sagittal maxillary growth in patients with unoperated isolated cleft palate.

OBJECTIVE: To examine the sagittal maxillary growth during mixed and permanent dentition in patients with unoperated isolated cleft palate. PATIENTS: A total of 41 patients with nonsyndromic unoperated isolated cleft palate, 16 with mixed dentition and 25 with permanent dentition. MAIN OUTCOME MEASURES: Cephalograms were analyzed to compare these patients with those with isolated cleft palate who had been repaired operatively as well with normal individuals. RESULTS: The unoperated patients in mixed dentition showed reduced anterior-posterior length of the maxilla. In adults with unoperated isolated cleft palate with permanent dentition, the measurements showed maxillary retrusion as well as reduction in the anterior-posterior maxillary length. CONCLUSION: Sagittal growth of the maxilla appears to be inhibited in patients with unoperated isolated cleft palate, which became more severe with age.

[Bolton tooth-size discrepancy among different skeletal malocclusion groups].

PURPOSE: To evaluate the differences in tooth size ratios and distributions of Bolton anterior and overall ratios among different skeletal malocclusions. METHODS: 180 subjects were involved in this study, each malocclusion group consisted of 60 subjects(30 males and 30 females). The mesio-distal width from left first molar to right first molar was measured, Bolton anterior and overall ratios were calculated. Student's t test, ANOVA, LSD and chi2 test were performed for statistical analysis with SPSS15.0 software package. RESULTS: No statistically significant sex difference was found in anterior or overall ratio in any malocclusion. Significant difference was found for all ratios between skeletal Class III and skeletal Class I, so with skeletal Class II. No significant differences in all ratios between skeletal Class I and Class II were noted. Significant difference was found in the distribution of subjects with anterior and overall ratio discrepancies between skeletal Class III and skeletal Class II. CONCLUSIONS: The mean anterior and overall ratios for skeletal Class III malocclusions are significantly greater than those for skeletal Class I and Class II. The number of subjects with anterior ratio discrepancies for skeletal Class III malocclusions are larger than that for skeletal Class I and Class II malocclusion.

[Sagital position of glenoid fossa in Angle Class II malocclusion with mandibular retrusion].

PURPOSE: To evaluate and compare the morphology and position of the glenoid fossa in patients with Class II malocclusion associated with mandibular retrusion and Class I malocclusion in the permanent dentition. METHODS: A sample of 26 subjects(12 males, 14 females, average age 13.4 years) with skeletal and dental Class II malocclusion associated with mandibular retrusion, was compared with a matched group of 31 subjects(12 males, 19 females, aged 12.9 years) with skeletal and dental Class I relationships. The lateral cephalograms were traced and the cephalometric analysis was taken by Nemotec Dental Studio 2006 software before orthodontic treatment. The comparisons between the two groups on the cephalometric measures for the assessment of glenoid fossa were performed by means of an independent samples t test using SPSS 15.0 software package. The correlation and regression analysis was also performed within the measures in the Class II group. RESULTS: The results showed there was significant difference of Wits, GF/Ptm-FH and GF-FMN between the two groups (P<0.01). There was a significant correlation between the GF-FMN vs. AOBO, GF-FMN vs. GF/S-FH, GF/S-FH vs.GF/Ptm-FH, S/Ptm-FH vs. GF/Ptm-FH in the Class II group. The regression equations of the GF-FMN vs. AOBO and GF-FMN vs. GF/S-FH were also obtained (P<0.05). CONCLUSIONS: The Class II malocclusion associated with mandibular retrusion patients have a posteriorly displaced glenoid fossa compared with Class I patients. Cephalometric measurement is a useful tool to evaluate the glenoid fossa morphology and position.

[Presurgical nasoalveolar molding in the treatment of infants with bilateral complete cleft lip and palate].

PURPOSE: To evaluate the curative effect of presurgical nasoalveolar molding (NAM) in the treatment of infants with bilateral complete cleft lip and palate (BCLP). METHODS: Nine infants with BCLP were included. Presurgical alveolar molding was used to bring the premaxilla back into proper alignment with the lateral segments in the maxilla arch. Presurgical nasal molding produced tissue expansion of the short columella and corrected the nasal tip cartilages. Up to 5 months of active treatment was needed before lip repair. Student's t test was used for data analysis with SPSS 15.0 software package. RESULTS: After presurgical NAM in 9 infants with BCLP, the posterior lateral alveolar segments were aligned while retracting the premaxilla, the premaxilla had been returned from 37.64mm to 29.94mm within the maxillary arch (P<0.01). The nasal alar base width was significantly reduced following NAM(P<0.05). The columella was nonsurgically lengthened from 1.13mm to 3.78mm(P<0.05). CONCLUSION: In order to obtain satisfactory lip-nose configuration for BCLP, presurgical NAM is useful in cleft lip and palate team approach.

[Evaluation of bone volume of alveolar cleft before and after bone graft].

OBJECTIVE: The aim of this study was to evaluate the changing of alveolar cleft bone volume before and after bone graft. METHODS: 11 complete unilateral alveolar cleft patients were scanned with dental CT before bone graft surgery and 3 months after surgery. Matlab7.0 software was used to calculate the bone volume of alveolar cleft before bone graft and bone bridge volume after bone graft. The method was clockwise identify the irregular area of alveolar cleft by several points at different vertical level, then calculated the irregular area of alveolar cleft and the volume of alveolar cleft using Matlab7.0 software. The volume of implant bone was evaluated with same method after 3 months surgery. The ratio of graft bone bridge volume and alveolar cleft volume was calculated. RESULTS: The maximum ratio of bone bridge volume and alveolar cleft volume was 114.99%, the minimum ratio was 13.36%. The average ratio was 71.80%, coefficient variation was 47.987. CONCLUSION: Bone bridge volume after bone graft is varying.

The effects of a newly designed twin-slot bracket on severely malpositioned teeth--a typodont experimental study.

The aims of this study were to design a twin-slot bracket featuring two horizontal slots and to examine its efficiency in tooth displacement. Based on the structure of a traditional edgewise bracket, an additional slot was added to a twin-slot bracket and the prototype products were fabricated for the typodont experiments. The orthodontic correction of malpositioned canines was conducted on a typodont to examine the efficiency of the twin-slot bracket in tooth displacement compared with a single-slot edgewise bracket. Three modalities of tooth movement requiring a heavy force moment, namely, axial rotation, mesiodistal tipping, and bodily translation, were conducted. The canine positions before and after simulation were measured and the changes identified. Statistical analysis was undertaken using a t-test to determine the significance of the differences in canine repositioning between the two bracket types. The results showed that in the twin-slot bracket group, the treatment changes in the canine position by derotation and uprighting were 40 +/- 3 and 25 +/- 2 degrees, respectively, compared with 20 +/- 5 and 10 +/- 2 degrees in the edgewise group (P < 0.01). When retracted into an extraction space with an initial 10 degrees of mesial tip, the mesiodistal angulation of the canines in the twin-slot bracket group remained unchanged while in the edgewise group the canines became distally tipped by 5 +/- 2 degrees (P < 0.01). The twin-slot bracket significantly increased the bracket width without reducing the interbracket span and therefore can generate increased force moments within the bracket, leading to an improved manipulation in tooth repositioning.