Evaluation of facial profile and incisor inclination preferences in orthodontically treated borderline nonextraction and extraction Class I and mild Class II malocclusions.

Space requirement and force are important factors in incisor position

Changes in maxillary incisor inclination and position after traction of unilateral vs bilateral maxillary impacted canines in nonextraction treatment: A cone-beam computed tomography study

To detect post-treatment change in the inclination and position of incisors in cases treated with orthodontic non- extraction therapy. The group consisted of 102 patients without extractions in lower and upper dental arch during orthodontic treatment. Cephalogram examination evaluated the position of the lower incisor to point A by Downs-pogonion line (-1 to APo) and inclination of the lower incisor to mandibular line (-1 to ML), position of the upper incisor to nasion-pogonion line (+1 to NPo), inclination of the upper incisor to nasion-sella line (+1 to NS) and the size of the inter-incisival angle between upper and central lower incisor (-1 to +1). In 58 % of cases, the difference in post-treatment and pre-treatment changes in the position of the (-1 to Apo) was within ± 2 mm, which we considered stable. Statistically significantly higher values after treatment were in unstable rather than in stable cases with values (-1 to Apo), (-1 to ML), (+1 to NPo). Statistically significantly lower value after the treatment was measured in unstable cases rather than in stable cases with a value (-1 to +1). There was no statistically significantly different value in stable and unstable cases after treatment in values (+1 to NS). The number of stable post-treatment cases was only 16 % higher than the number of unstable cases. With the increasing value (-1 to Apo), the value (-1 to ML) and (+1 to NPo) increased, the value (+1 to -1) decreased. The value (-1 to NS) not after treatment was not statistically significantly different in stable and unstable cases (Tab. 6, Fig. 4, Ref. 27).

Objective:To test the null hypothesis that there is no effect of esthetic perception of smiling profile in three different facial types by a change in the maxillary incisor inclination and position.Materials and Methods:A smiling profile photograph with Class I skeletal and dental pattern, normal profile were taken in each of the three facial types dolichofacial, mesofacial, and brachyfacial. Based on the original digital image, 15 smiling profiles in each of the facial types were created using the FACAD software by altering the labiolingual inclination and anteroposterior position of the maxillary incisors. These photographs were rated on a visual analog scale by three panels of examiners consisting of orthodontists, dentists, and nonprofessionals with twenty members in each group. The responses were assessed by analysis of variance (ANOVA) test followed by post hoc Scheffe.Results:Significant differences (P < 0.001) were detected when ratings of each photograph in each of the individual facial type was compared. In dolichofacial and mesofacial pattern, the position of the maxillary incisor must be limited to 2 mm from the goal anterior limit line. In brachyfacial pattern, any movement of facial axis point of maxillary incisors away from GALL is worsens the facial esthetics. The result of the ANOVA showed differences among the three groups for certain facial profiles.Conclusion:The hypothesis was rejected. The esthetic perception of labiolingual inclination and anteroposterior of maxillary incisors differ in different facial types, and this may effect in formulating treatment plans for different facial types.

This study was designed to determine the perceptions of lay people and dental professionals with respect to minor variations in anterior tooth size and alignment and their relation to the surrounding soft tissues. Smiling photographs were intentionally altered with one of eight common anterior esthetic discrepancies in varying degrees of deviation, including variations in crown length, crown width, incisor crown angulation, midline, open gingival embrasure, gingival margin, incisal plane, and gingiva-to-lip distance. Forty images were randomized in a questionnaire and rated according to attractiveness by three groups: orthodontists, general dentists, and lay people; 300 questionnaires were distributed. The response rate was 88.2% for orthodontists, 51.8% for general dentists, and 60.6% for lay people. The results demonstrated threshold levels of noticeable difference between the varying levels of discrepancy. A maxillary midline deviation of 4 mm was necessary before orthodontists rated it significantly less esthetic than the others. However, general dentists and lay people were unable to detect even a 4-mm midline deviation. All three groups were able to distinguish a 2-mm discrepancy in incisor crown angulation. An incisal plane cant of 1 mm as well as a 3-mm narrowing in maxillary lateral incisor crown width were required by orthodontists and general dentists to be rated significantly less esthetic. Lay people were unable to detect an incisal plane asymmetry until it was 3 mm, or a lateral incisor narrowing until it reached 4 mm. Threshold levels for open gingival embrasure and gingiva-to-lip distance were both at 2 mm for the orthodontic group. Open gingival embrasure became detectable by the general dentists and lay people at 3 mm, whereas gingiva-to-lip distance was classified by these groups as noticeably unattractive at 4 mm. The results of this study show that orthodontists, general dentists, and lay people detect specific dental esthetic discrepancies at varying levels of deviation, which may aid the dental professional in making specific treatment recommendations.

Objective To investigate the changes in incisor inclination and soft tissue profile before and after surgical-orthodontic treatment and the effect of extraction treatment planning on the curative effect of skeletal class Ⅲ patients. Methods The subjects consisted of 51 skeletal Class Ⅲ patients treated with the surgical-orthodontic approach. They were divided into 2 groups: extraction group (n=21) had an extraction of the maxillary premolars, and non-extraction group (n=30) had no extractions. Lateral cephalograms were analyzed before treatment (T0), 1 month before surgery (T1), and after debonding (T2). 9 items of hard tissue indexes, 10 items of dental indexes and 15 items soft tissue indexes were selected. After the measurement of variables, SPSS 19.0 was used to analyze and compare the data. Results The cephalogram analyses showed that there was no obvious difference between extraction group and non-extraction group before treatment. In pre-operation treatment, maxillary incisors' decompensation and the decrease of protrusion were more obvious in the extraction group (U1-NA/° reduced by 4.38°, U1-NA/mm reduced by 2 mm) ; conversely, there was an increasing trend of compensation of maxillary incisors in the non-extraction group. The mandibular incisors in both groups were significantly decompensated(L1-NB / ° increase of 12.4 ° and 9.52 ° respectively) and the lower lip thickness was thinner. After treatment, the position of upper and lower lip in the extraction group were more posterior than those in the non-extraction group, and the changes of ANB Angle were more obvious after surgery. Conclusions For skeletal Class Ⅲ patients with similar craniofacial features, pre-surgery extraction decompensates incisor inclination better, which may results in greater improvement of soft and hard tissue morphology after orthognathic surgery. Key words: Skeletal Class Ⅲ malocclusion; Surgical-orthodontic treatment; Extraction orthodontic therapy; Cephalometric analyses; Compensatory

This study aims to provide craniofacial features and incisor position prediction models among esthetics population after orthodontic treatment. A total of 338 patients with esthetic profiles were selected from 1 055 post-orthodontic adults based on inclusion and exclusion criteria and scored by five dental students. Mean values of cephalometric measurement were demonstrated with gender and sagittal skeletal pattern (ANB) differences assessed by generalized estimating equation. Correlations among age, skeletal, and soft tissue variables in different genders were determined. Multivariate analysis was used to assess the influence of skeletal and soft tissue variables on orthodontic incisor position. Within the esthetic cohort after orthodontic treatment, gender differences existed in cranial and mandibular length, mandibular rotation, protrusion of pogonion, inclination of maxillary incisors, upper lip thickness, lower 1/3 face height, and nose protrusion. However, in class Ⅰ malocclusion, the development of the chin showed no significance, whereas the protrusion of the lower lip significantly differed between genders, with less protrusion in males. In males, the protrusion of lip and chin varied among groups, with thinner basic upper lip thickness of class Ⅱ than class Ⅰ and greater lower lip height of class Ⅲ than class Ⅰ. In females, the protrusion and height of the upper lip and chin varied in groups, with thicker basic upper lip thickness of class Ⅲ than class Ⅰ. Upper lip thickness, female basic upper lip thickness, and female lower lip height were correlated with age. The protrusion of the upper lip was mainly correlated with posterior cranial base, mandibular body length, ANB in male and SNA, ANB, sagittal maxillary length, mandibular rotation, and protrusion of pogonion in female. The protrusion of the lower lip in males was mainly correlated with ramus height, mandibular rotation, protrusion of pogonion in male and ANB, mandibular rotation, and protrusion of pogonion in females. After employing skeletal variables to fit dental parameters, optimal results were achieved in male IMPA (adjusted R2=0.712) and female G Vert-U1 (adjusted R2=0.795). After employing skeletal and soft tissue variables simultaneously, optimal results were achieved in male and female G Vert-U1, which was mainly influenced by the protrusion of the chin and nasal base in males (adjusted R2=0.836) and the protrusion of the nasal base as well as ANB in females (adjusted R2=0.842). This study demonstrated the craniofacial features of esthetics population after orthodontic treatment and revealed the correlation of gender, age, skeleton, and soft tissues to provide reliable prediction models for aesthetic orthodontic incisor position.

This study aims to examine the profile as well as the dentoalveolar and skeletal effects of extraction or nonextraction treatment in a wide range of patients including Class I and Class II, division 1 cases. Results achieved with extraction and nonextraction modalities have also been compared. The study was performed on pretreatment and posttreatment lateral cephalograms of 87 orthodontic patients. There were no significant differences between the pretreatment values of extraction and nonextraction Class I groups, whereas SN-GoGn (degrees), maxillary incisor to A-Po (degrees), mandibular incisor to A-Po (mm), Co-Gn (mm), overjet (mm), and overbite (mm) measurements of extraction Class II group were significantly higher before the treatment. After treatment, these differences were eliminated in the Class II group; however, incisors were significantly protruded in both nonextraction groups. No other differences in profile or lip position were found between the extraction and nonextraction groups. The results of this study indicate that in successfully treated cases, whether by extraction or nonextraction, the same soft and hard tissue profile posttreatment end points were reached except for the incisor positioning, which is rather easier to anticipate than profile and soft tissue changes. The simple statement that extraction means a more retrusive or dished-in profile seems to be unacceptable. It seems that a more thorough assessment and investigation including pretreatment extent of crowding and factors related to anchorage, soft tissue thickness, and strain should be carried out.

Cephalometric appraisal of patients treated with fixed lingual orthodontic appliances: Historic review and analysis of cases

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ObjectiveTo test the null hypothesis that SmartClip self-ligating brackets are more effective than conventional brackets for initial mandibular alignment and identify influential factors.MethodsFifty patients were randomly allocated to two equal treatment groups by using an online randomization program: self-ligating group (SmartClip brackets) and conventional group (Gemini brackets). The archwire sequence was standardized. Changes in anterior irregularity index, intercanine width, and intermolar width were assessed on plaster models at 8th and 16th weeks. Changes in incisor position and inclination were assessed on lateral cephalometric radiographs at 16 weeks. Intragroup and intergroup comparisons were performed with paired t-test and Student's t-test, respectively. Multiple linear regression was performed to identify variables affecting improvement in anterior ambiguity.ResultsData of 46 patients were analyzed; those missing an appointment (n = 2) or showing bracket breakage (n = 2) were excluded. Incisor inclination (p < 0.05), intercanine width (p < 0.05), and intermolar width (p > 0.05) increased at 8 and 16 weeks in both the groups; no significant intergroup differences were noted (p > 0.05). Initial anterior irregularity index and intercanine width change were significantly associated with improvement in anterior irregularity (p < 0.001).ConclusionsThe null hypothesis was rejected. Bracket type has little effect on improvement in anterior ambiguity during initial mandibular alignment.

Esthetic perception of mandibular anterior teeth during speech and dynamic smile.

Background Understanding the cephalometric factors that affect the mentolabial angle and lower lip eversion is essential for orthodontics. The objective was to evaluate the influence of various skeletal and dentoalveolar cephalometric features associated with the mentolabial angle and lower lip eversion in young adults.Material and Methods This cross-sectional study assessed lateral head radiographs of individuals between the ages of 15 and 40 years. Two trained and calibrated evaluators performed angular and linear cephalometric measurements utilizing BlueSky Plan 4 software. The variables evaluated in this study included the presence of the mentolabial angle, labial eversion, overjet, and the position and inclination of the lower central incisors (measured by I-NB, I.NB, IMPA) as well as the upper central incisors (measured by I-NA, I.NA, UIPP). Additionally, we assessed the sagittal positions of the maxilla and mandible using SNA and SNB measurements, along with the sagittal and vertical skeletal relationships determined by the ANB and FMA angles. We applied multiple linear and binary logistic regression tests for statistical analysis (p<0.05).Results 138 radiographs were evaluated (73 females and 65 males). The mentolabial angle is, on average, 7.68° greater in women than men (p=0.001). An increase in the IMPA and overjet decreases 0.40° (p=0.012) and 2.02° (p=0.003) in the mentolabial angle, respectively. Likewise, females are 82% less likely to experience lip eversion than males (exp B = 0.18, 0.05 to 0.60 CI 95%; p=0.006). Furthermore, for each degree increase in lower incisor inclination (I. NB) or overjet, the risk of developing lip eversion increases by 1.17 times (1.02 - 1.34 CI to 95%, p=0.023) and 1.85 times (1.23 - 2.78 CI to 95%, p=0.003), respectively.Conclusions The inclination of the lower incisors and the overjet primarily influences the mento-labial angle. Women tend to have a greater mento labial angle, meaning it is more retrusive, compared to men. Additionally, the likelihood of lip eversion is higher in males. For each degree of increased lower incisor inclination or overjet, the risk of developing lip eversion also rises. Key words:Cephalometry, Chin, Dental Esthetics, Lip.

Objective To investigate the movement distance and moving pattern of incisors and molars after orthodontic treatment with four second premolar removal in the slight dental protrusion patients.Methods 26 patients treated in Dept.of Orthondontics,Hua Xi Dental Hospital were recruited into this studdy .The moving distance and pattern of incisors and first molars were measured relative to the post-treatment occlusal plane, palatal plane and mandibular plane on the X-ray cephalometries.Results In the upper arch,the anterior segnemt took up 50.4±11.5% of the extraction space,while in the lower arch it was 46.2±10.7%.the rotation center of the upper central incisor located at -4.28～11.96 mm apical to the apex point,while the lower central incisors located 0.85～25.25 mm apical to the apex.All the molars were moved bodily.Conclusions The slight bimaxillary dental protrusion patients can be successfully treated with four second premolar removal.Following the treatment,the position and inclination of the upper incisors would be properly maintained.Profile esthetics and smile fullness would be achieved as well. Key words: Second premolar; Extraction; Teeth movement; Esthetics

Changes in anteroposterior position and inclination of the maxillary incisors after surgical-orthodontic treatment of skeletal class III malocclusions.