ABSTRACT
@#It has been traditionally believed that a 1:1 cortical bone remodeling/tooth movement ratio has been preserved during orthodontic treatment for tooth movement, with the alveolar bone on the tension side growing and the alveolar bone on the pressure side resorbing to maintain the balance of the alveolar bone. However, recent studies have shown that alveolar bone loss has been found in patients who have undergone orthodontic treatment, suggesting that the alveolar bone does not change as the teeth change over time. Whether the morphology of the alveolar bone will change when the anterior teeth are moved has been the clinical focus. The changes of anterior alveolar bone in patients who have undergone tooth extraction after orthodontic treatment were summerized by literature review in this paper. The results of the review showed that the alveolar bone at the lingual/palatal root-cervical site of the anterior root is more prone to bone loss after extensive movement of the anterior teeth. With the development of imaging technology, CBCT is now more commonly used for analysis instead of two-dimensional images for measurement, as its results are more accurate. However, there are few multifactorial studies in which CBCT has been used to assess the morphological changes in the alveolar bone. The focus of future research is to compare the long-term changes in the anterior alveolar bone of patients of different ages based on three-dimensional imaging, and to study the correlation between different skeletal features, tooth movement patterns and alveolar bone remodeling.
ABSTRACT
Objective:To observe the clinical effect of TOMY self-ligation appliance technique in the treatment of anterior crossbite and moderate crowding, and to explore its clinical application.Methods:A patient, manifested as anterior crossbite and moderate dentition crowing, diagnosed as Angle class Ⅲ subclass malocclusion, MaoⅡ1+Ⅰ1 malocclusion, high angle,and facial asymmetry, was selected.This patient was treated with TOMY self-ligation appliance technique without tooth extraction.The length and width of the dental arch, the width of the alveolar bone and the width of the basal arch were measured before and after treatment;the lateral radiographs of the patient were taken too.Results:After treatment,the upper and lower dentition arranged in neat rows, reached a neutral occlusal relationship;SNA, SNB and ANB had no obvious changes;the lip inclination of anterior teeth was increased by 10 degrees, and reached the normal value;the upper and lower dental arch width, alveolar bone width, basal bone arch width and dental arch length were lower than before treatment.Conclusion:For the patient with anterior crossbite and moderate dental crowding treated with non-extraction, the TOMY self-ligation technique can be considered to use, by increasing the arch width and length to improve the anterior crossbite and moderate crowding, in order to achieve the effective treatment.
ABSTRACT
Objective@#To investigate the effects of the first molar on the eruption of the third molar by comparing the changes of the third molar position after orthodontic treatment in different tooth extraction modes. @*Methods@#39 cases of adolescent patients were selected and divided into three groups:the first molar extraction, first premolar extraction and non-extraction.The pretreatment, posttreatment panoramic radiographs were measured to analyze the change of the third molar position among these groups.@*Results@# There were significant differences (P< 0.05) in the average annual variation of the third molar eruption space and angle. The changes in first molar extraction group were larger than that in premolar extraction group and non-extraction group. The average annual variation of the third molar eruption space, three groups were (2.38 ± 1.62) mm, (1.61 ± 0.90) mm and (1.08 ± 1.49) mm; the average annual variation of eruption angle, the three were 1.89° ± 1.93°, 1.37° ± 1.16° and 0.83° ± 1.74°.@*Conclusion @#Compared with conventional treatment, mandibular first molar extraction can significantly increase the third molar eruption space and improve its eruption angle, which is beneficial to the eruption of the third molar.
ABSTRACT
The effect of extraction and nonextraction treatment on the soft tissue profile of the subjects borderline Angle classⅡ division 1 malocclusion is concerned mainly by orthodontists.This article reviewes the effect of extraction and nonextraction treatment on the soft tissue profile of the subjects with Angle classⅡ division 1 borderline patients and the important factors(such as differences between the types of tooth extraction and growth).The aim is to guide clinic diagnosis and treatment for borderline Angle classⅡ division 1 malocclusion.
ABSTRACT
Objective:To evaluate the effectiveness and treatment feature of maxillary incisor extraction in orthodontics.Methods:9 patients underwent orthodontic treatment with maxillary incisor extraction,5 female and 4 male,with an average age of 1 7.2 years at the start,were included.5 patients were treated by extraction of both upper incisors and lower first premolars,4 by extraction of the abnor-mal incisor and the first premolars in the other three quadrants.Cephalometric and Bolton index analysis were carried out.Results:Sat-isfactory treatment results were observed in all patients.Before treatment the predicted Bolton index of the patients of the anterior ratio and the overall ratio were 80.1 4% and 91 .3%,after orthodontic treatment 78.68% and 90.28%,respectively.Cephalometric analysis showed that U1 -NA(mm),U1 -NA,L1 -NB(mm),L1 -NB,U1 -SN,L1 -MP,UL-E and LL-E were decreased(P <0.05).Conclu-sion:Individual treatment plan based on Bolton index analysis and the corresponding techniques and methods,the patients with abnor-mal upper incisors can be effectively treated with the extraction of maxillary incisors.
ABSTRACT
Objective:To study the tooth movement in the orthodontic treatment by Empower appliance following tooth extraction. Methods:40 cases with bimaxillary dentoalveolar protrusion were divided into 2 groups(n =20).After extraction of all first premolars of each case,the patients were treated by Empower appliance and Damon3-Mx appliance respectively without palatal enhance measure. Before and after treatment the patients were examined by cephalometric roentgengraphy with 1 9 measurements,the data were analysed by independent sample t test.Results:Tooth indicators∠UI-SN,∠UI-PP,∠L1 -MP,∠U1 -L1 ,UIE-PTV and LIE-PTV before and after the treatment in each group,and the variations between the 2 groups were significantly different(P 0.05).Conclusion:Empower appliance is more effective than Damon3-Mx in the treatment of bimaxillary dentoalveolar protrusion by anterior tooth torque control,upper and lower front teeth adduction and improvement of soft tissue lateral profile.
ABSTRACT
Background: Extraction of all 1st premolars in the orthodontic treatment of Class II div 1 malocclusion has been associated with a decrease in vertical dimension of occlusion thus predisposing the patient to TMJ disorders. Objectives: To evaluate the vertical changes occurring in patients having class II div 1 malocclusion, treated orthodontically with 1st premolar extractions & compare these changes with those occurring in patients treated orthodontically without extractions. Method: Pre-treatment & Post-treatment Lateral Cephalogram radiograph of 11 patients having CL-II div1 malocclusion treated without extraction and 16 patients treated with the extraction of all 1st premolars were analyzed and compared to observe the changes in the anterior facial height. Result: the orthodontic treatment of Cl-II div 1 malocclusion cases treated with a non-extraction approach leads to a statistically significant increase in the anterior facial height due to the downward & backward rotation of the mandible. The cases treated with the extraction of all 1st premolars also show the statically significant increase in the anterior facial height but this increase was less than that observed for the non-extraction group. Conclusion: this study does not support the theory that the first premolar extractions reduce the vertical dimension of occlusion and predispose the extraction patients to TMJ disorders.
ABSTRACT
Objective To investigate the change and correlation between hard-tissue and soft-tissue in patients with class III malocclusion after premolar extraction treatment. Methods Thirty-four adult patients with skeletal classⅢmalocclusion who met the including criteria were included in this retrospective study. The lateral cephalographs were traced and analysed before and after the treatment. Results After orthodontic treatment,the values of long axis of upper incisors and S-N angle (U1-SN) and long axis of lower incisors-mandibular plane (L1-MP) were decreased, and the angle of man-dibular plane (MP-FH) was increased (P<0.01). The SL line was used as a reference, the protrusion of upper incisor (UI-SL) and upper lips (UL-SL) was decreased, and the protrusion of lower incisors (LI-SL) and lower lips (LL-SL) was also de-creased after orthodontic treatment (P<0.05 or P<0.01). There was no significant difference in the relevant measurements of chin. The retraction of upper incisor (△UL-SL) was the only measurement that was positively correlated with upper lip re-traction (△UI-SL). The retraction of upper incisor (△UI-SL) and lower incisor (△LI-SL) were positively correlated with the lower lip retraction (△LL-SL). There was a positive correlation between△UI-SL and△LL-SL. Conclusion The soft-tissue profile improved significantly after four premolars extraction. The change of soft-tissue profile was moderate correlated with hard-tissue.
ABSTRACT
Objective To examine the effects of fixed appliance and micro-implant on the improvement of facial profile in patients with protruding.Methods 30 protruding cases were treated by fixed appliance and micro-implant.Cephalometric data before and after treatment were measured and analyzed to assess the effects.Results The upper incisors were retracted 6.5 mm.The upper lip was retracted 3.8 mm.The lower incisors were retracted 5.8 mm.The lower lip was retracted 5.6 mm.UL-E was retracted 3.21 mm.LL-E was retracted 3.67 mm.NLA was changed from 86.7°to 103.7°.The U1-SN,U1-Y,L1-MP,L1-Y,UL-Y,LL-Y,UL-E,LL-E,and NLA demonstrated significant differences between pre-and post-treatment.Conclusions Fixed appliance and micro-implant might retract the anterior teeth and lead to an improvement of facial profile.
ABSTRACT
OBJECTIVE: This study was performed to investigate the influences of extraction and nonextraction treatment on smile esthetics by measuring dental arch width changes. METHODS: Pretreatment and posttreatment study models of 30 first premolar extraction cases and 30 nonextraction cases were randomly selected to determine whether extraction treatment results in narrow dental arches, and a consequent unaesthetic smile. Arch widths were measured from the cusp tips of the canines and the first molars. Posterior arch widths were also measured at a constant arch depth derived by averaging randomly chosen nonextraction models. RESULTS: The intercanine widths increased significantly in the extraction sample, whereas the intermolar widths decreased significantly. The arch width at a standardized arch depth was significantly wider in the extraction subjects. CONCLUSION: These results elucidate that constriction in arch width is not a materialized consequence of extraction treatment. It leads to postulate that an esthetically compromising effect from narrow dental arches on smile is hardly anticipated with extraction treatment.
Subject(s)
Bicuspid , Constriction , Dental Arch , Esthetics , MolarABSTRACT
The purpose of this study was to investigate the pretreatment and posttreatment dentofabial characteristics of non-extraction patients with Class I malocclusion. And to compare this result with matched non-orthodontic normal occlusion and Class I premolar extraction patients. Such comparison might help identify morphologic characteristics of the non-extraction patients. Initial and final cephalometric evaluation were compared in a sample of 22 patients with Class I malocclusions treated in non-extraction manner with edgewise appliance and MEAW. The mean age of the total population was 14 years 9 months and the average treatment time was 2 years 8 months. 32 landmarks were located and digitized on each cephalogram. From these landmarks, 24 linear and angular dimension were obtained Student's t-test were used to compare the pretreatment - posttreatment results, Nonextraction - Normal groups, and nonextraction - Extraction groups. Significance was predetermined at p < or = 0.05. The results were gas follows. 1. Before treatment, the mean value of the ODI was 69.9degrees, APDI was 82.1degrees, CF was 152degrees, and El was 152degrees in the non-extraction groups. 2. The skeletal pattern of the non-extraction groups were similar with non-orthodontic normal group3, but the non-extraction groups had larger interincisal angle. 3. Comparison between groups treated with and without extraction indicated at pretreatment, the extraction groups had more protrusive lips, smaller interincisal angle, and El. 4. After treatment, there was no significant changes in the skeletal pattern of the non-extraction groups, but uprighting of the maxillary and mandibular first molar and decrease of the interincisal angle were seen.