Intermolar Width Research Articles

Predictability of crowding resolution in clear aligner treatment

BackgroundTo assess the predictability of crowding resolution and the efficacy of different strategies to gain space during clear aligners treatment.MethodsA total of 10 clinicians were randomly recruited using the Doctor Locator by Align Technology (California). For each clinician, four consecutive patients treated with aligners and manual stripping were selected for a total of 40 subjects. Thus, 80 arches were collected and uploaded on the Orthoanalyzer software for arch measurements. The data were gained on the starting arch form (T0), on the virtual arch developed with digital planning (vT1), and on the arch form achieved at the end of the aligner sequences (T1). The following parameters were scored: Little's Irregularity Index, transversal arch diameters, (intercuspid, interpremolar, and intermolar width), incisor position/arch length, and enamel interproximal reduction (IPR).ResultsFor all the measurements, statistically significant differences were found at different stages. The predictability of crowding resolution was very high, ranging from 87% in the upper arch and 81% in the lower one. Among the different strategies to gain space, variations in sagittal incisor position were predictable, with a value of 70% both in the upper and lower arch. Conversely, changes in arch diameters were less reliable varying between 49 and 67% in the lower arch and 59–83% in the upper one. Moreover, IPR was the least accurate procedure, wavering at 49% in the upper arch and 42% in the lower arch.ConclusionsThe predictability of crowding resolution during treatment with aligners was high. However, the virtual arch forms obtained at the end of digital planning (vT1) did not correspond with the arch forms at the end of the aligner sequences (T1). The IPR was the least predictable strategy to gain space, being, perhaps, an operator-dependent procedure.

Dentoskeletal effects of rapid maxillary expander therapy in early mixed dentition patients with different vertical growing patterns without posterior crossbite: A retrospective study

This study aimed to analyze the variation of dentoskeletal effects after rapid maxillary expander therapy in subjects with different vertical growth patterns. The study sample consisted of 94 patients (32 males, 62 females; mean age 8.9 ± 1.5 years) treated with rapid maxillary expander (RME) anchored on first permanent molars. For each subject, lateral cephalograms and maxillary digital dental casts were available before RME, immediately after appliance removal, and 1 year after appliance removal. All the subjects were divided into 3 groups according to their vertical facial patterns (low-angle, normal-angle, and high-angle). Cephalometric analysis was conducted on lateral cephalograms. The virtual 3-dimensional models were used to analyze the torque of the first permanent molars and intercanine and intermolar width. The differences between the vertical facial subgroups were contrasted by analysis of variance multicomparison test (P<0.05). In the short-term (from before to immediately after RME removal), high-angle subjects showed a mandibular clockwise rotation compared with other groups. No significant long-term vertical and sagittal skeletal changes (from before to 1 year after RME removal) were found between the groups. A greater increase in maxillary molar torque was observed in high-angle subjects than in the other groups. The low-angle patients showed a greater increase in the intercanine diameter. Hyperdivergent subjects showed increased buccal tipping of the anchor molars after the expansion. Hypodivergent and normodivergent subjects showed lower buccal tipping after the expansion and an increased expansion effect in the anterior region.

Dimensional changes of upper airway after slow vs rapid miniscrew-supported maxillary expansion in adolescents: a cone-beam computed tomography study

BackgroundTo date, the effects of different activation rates of miniscrew-supported expanders on the airway have not been compared. Hence, the purpose of this retrospective study was to evaluate and compare the effects of slow and rapid miniscrew-supported maxillary expansion on the upper airway dimensions using cone-beam computed tomography (CBCT).MethodsData of 20 patients (Age 12 to 16 years old) treated using miniscrew-supported expanders at the Faculty of Dentistry, Alexandria University was collected. The patients were equally divided into two groups according to the activation protocol; slow maxillary expansion (SME): activation once every other day, and rapid maxillary expansion (RME): activation twice daily. CBCT scans obtained pre-expansion and 5 months post-expansion were used to evaluate the changes in the upper airway dimensions. Comparisons between the two time points within each group were done using paired samples t-test. SME and RME groups were compared using independent samples t-test. Significance level was set at p < 0.05.ResultsBoth groups showed a significant increase in anterior, middle, and posterior nasal cavity width. SME resulted in significantly greater increase of the anterior nasal cavity width than RME (Mean difference between the groups, 2.64 mm; 95% CI, 0.83, 4.45; p = 0.007). The dimensions of the retropalatal and retroglossal airways did not change significantly in either group. Both groups resulted in a significant increase of maxillary width, palatal width, and inter-molar width. RME showed a significantly larger increase of inter-molar width than SME (Mean difference between the groups, − 2.44 mm; 95% CI, − 3.88, − 1.00; p = 0.002).ConclusionsThe use of either a slow or rapid activation protocol is effective in expanding the nasomaxillary complex, with greater expansion achieved in the anterior section of the nasal cavity using the slow rate. However, the expander design employed in the current study does not affect the dimensions of the retropalatal or retroglossal airways.

Qualitative and quantitative three-dimensional evaluation of maxillary basal and dentoalveolar dimensions in patients with and without maxillary impacted canines

BackgroundThis study aimed to three-dimensionally evaluate the qualitative and quantitative maxillary basal, dentoalveolar, and dental dimensions in patients with unilateral or bilateral maxillary impacted canines relative to their normal peers.Materials and methodsThis is a retrospective comparative study. Cone-beam computed tomography images of one hundred and fifty adult patients were divided into three equal groups: unilateral, bilateral, and control groups. Each had 50 patients that were three-dimensionally analysed. The quantitative measurements involved three basal (molar basal width, premolar basal width, and arch depth), seven dentoalveolar (molar alveolar width, premolar alveolar width, inter-molar width, inter-premolar width, inter-canine width, arch length, and arch perimeter), and two dental (canine length and width) measurements. The qualitative measurements included four bone density areas (buccal, lingual, mesial, and distal) around the maxillary impacted canines.ResultDifferences between the three groups were statistically different for the quantitative measurements involving the two basal variables (molar basal width and premolar basal width) and all measured dentoalveolar variables; these were smaller in the unilateral and bilateral groups compared with the control group (p < 0.001). Unilateral and bilateral impacted canine groups showed significantly wider and shorter canines than the control group (p < 0.001). The qualitative measurements (the four bone density areas) around unilateral and bilateral impacted canine groups showed significantly greater density than the control group (p < 0.001). There was no significant qualitative or quantitative difference between the unilateral and bilateral impacted canines. The three groups had no significant variations in terms of arch depth.ConclusionMaxillary unilateral and bilateral canine impactions are associated with reduced basal and dentoalveolar dimensions as well as wider and shorter maxillary canines compared to normal peers. The quality of bone around unilateral and bilateral impacted maxillary canines is higher than in non-impacted cases. Unilateral and bilateral canine impactions have quite similar qualitative and quantitative parameters.

Accuracy of Invisalign Progress Assessment with Clear Aligners: A Retrospective Study

Objective: The objective of this study was to detective the accuracy of model superimposition and automatic analysis for upper and lower dentition width in Invisalign Progress Assessment during the process of clear aligners. Methods 19 cases were included in this study. Pre-treatment dental cast(T0) and post-treatment dental cast after staged treatment(T1) were available for three-dimensional model superimposition. Subsequently, movements of maxillary teeth in horizontal plane (cross section) after staged treatment, width of upper and lower dentition were measured by three-dimensional model superimposition in real world and Invisalign Progress Assessment separately. Consequently, the data collected from these two methods was compared. Results In Invisalign Progress Assessment, movements of maxillary teeth in horizontal plane after staged treatment was 2.31（1.59,3.22 ） (median (upper quartile, lower quartile)) millimeter (mm), while in three-dimensional model superimposition, the result was 1.79（1.21,3.03）mm. The difference between two groups is significant(P＜0.05). Intercanine width upper, intermolar width upper, intercanine width lower, and intermolar width lower were 36.55±2.76mm, 56.98±2.62mm, 28.16±1.85mm, 53.21±2.72mm separately in Invisalign Progress Assessment and were 36.48±2.78mm, 56.89±2.58mm, 28.05±1.85mm, 53.16±2.64mm separately in three-dimensional model analysis, which were no significant difference among these groups (P＞0.05). Conclusions The data from Invisalign Progress Assessment was not in parallel with what achieved from model superimposition with palate as reference completely. The accuracy of model superimposition in Invisalign Progress Assessment needs further investigation, whereas the accuracy of model analysis in Invisalign Progress Assessment was accurate. Thereby, results from Invisalign Progress Assessment should be interpreted with caution by the orthodontist in clinic.

Longitudinal changes in the dental arch width and symmetry in identical and fraternal twins

This study aimed to assess growth-related dental and symmetry changes in the dental arch within and between identical and fraternal twins in mixed and permanent dentition. Three-dimensional scanned dental models of eligible subjects were selected from the Forsyth-Moorrees Twin Study sample. This retrospective cohort study was carried out on 36 identical (18 pairs) and 28 fraternal (14 pairs) twins in mixed dentition and 36 identical (18 pairs) and 38 fraternal (19 pairs) twins in permanent dentition stages on the basis of the availability of the dental casts scanned each year from each group (Table I). Linear measurements from dental casts were performed in patients aged 8-16 years. Student t test and Pearson's correlation were used to compare the symmetry between and within the identical and fraternal twins. The resemblance and heritability patterns were retrospectively obtained from the Pearson correlation coefficient and Falconer's heritability test (H2= 2 × b). Adjusted mixed-effects estimates and 95% confidence intervals were calculated to test the association between age and dental parameters for both mixed and permanent dentition groups. Intercanine and intermolar widths significantly increased (P<0.05) during the mixed dentition but became stable after 13 years old. No statistically significant differences were found in arch symmetry between the 2 groups (ie, identical and fraternal) in any of the included measurements. Evaluation of the resemblance and heritability pattern showed nonsignificant results for all variables measured (H2 range, -0.67 to 0.56). The dental arch becomes wider at a higher rate in the canine region than the molar region in both the mixed and early permanent dentition. The dental arches of twins develop symmetrically, and their growth is not mainly affected by genetics. Asymmetrical teeth will maintain their relative position to reference planes throughout growth.

Surgically assisted rapid palatal expansion: is the pterygomaxillary disjunction necessary? A finite element study

Transverse discrepancy is an important factor in determining facial esthetics. It has been shown there is an inverse correlation between the buccal corridor width and the intercanine and intermolar widths. Despite the fact midpalatal expansion is the treatment of choice for growing subjects, for skeletally mature subjects the rapid palatal expansion has limited orthopedic effects, and surgically assisted rapid palatal expansion (SARPE) is preferred. SARPE has shown inconsistencies depending on the surgical technique and/or expander device design. Some authors suggest that median and lateral osteotomies are sufficient to achieve the desired transverse dimensions using the SARPE procedure, while others recommend additional surgical separation of the pterygomaxillary junction. There are still controversies regarding the pterygomaxillary sutures (PMS) disjunction effect. Therefore, this study aimed to evaluate the displacement and stress distribution of the craniofacial structures resulting from SARPE, either with or without PMS osteotomy, using two different expander design (tooth-borne and tooth-bone-borne) using finite element method and finite element analysis (FEM/FEA). Regardless of the maxillary expander device type, both SARPE surgical techniques effectively produced maxillary expansion. SARPE with PMS osteotomy presented parallel maxillary expansion, and reduced stress values in the craniofacial and maxillofacial structures.

A Comparative Study of Intermolar Arch Width before and after Orthodontic Treatment in Alignment Phase among Class II Div-I Patients

For an orthodontist, changes in the width of the arch caused by treatment with fixed appliances are important. Understanding these changes is critical to your physician's planning for treatment. Aim: The purpose of the study was to compare and determine the width of the inter- molar arch in cases of class II, division 1 before and 4 months after fixed orthodontic treatment. Study Design: A cross-sectional intervention study. Place and Duration: In the Orthodontics department of Jam Ghulam Qadir Govt. Hospital, Hub Govt of Balochistan and Bhitai Dental and Medical College Mirpurkhas, for six-months duration from July 2021 to December 2021. Methods: 200 Class II Division 1 malocclusion patients were included by the purposive non- probability technique of sampling. 14 to 28 years was the patients age range. The impressions of the upper arch were measured before and six months after orthodontic treatment, and the maxillary inter-molar width was measured. Standard 0.012 Nitinol to 0.019x0.028 arch wires were used. The width of the inter-molar arch was taken as the transverse distance from the central fossa of the 1st molar on one side of the same arch to the central fossa of the 1st molar on the same arch of other side. Results: 200 Class II Division 1 malocclusion patients were included (120 males and 80 females) with 14-28 years of age range and 18.24 ± 2.8 years of mean age. The mean values of the inter-molar width in the entire sample were 46.01 mm ± 2.58 mm in T1 and 48.201 mm ± 2.70 mm in T2 (Table 2). The mean width of the inter-molar arches in men and women before treatment was 43.7± 2.2 mm and 46.2 ± 2.8 mm. Though, the mean T2 inter-molar arch width after treatment was 47.1 ± 2.3 mm in women and 48.3 ± 2.7 mm in men. Conclusion: There was an average rise in the width of the inter-molar arch by 1.7 mm before and after treatment, therefore the orthodontist should consider the mechanics of expanding the arch, especially when the treatment plan does not include extractions. Keywords: width of the inter-molar arch, shape of the arch, malocclusion class II division 1

Obstructive sleep apnea and anatomical structures of the nasomaxillary complex in adolescents.

The aim of the present study was to reveal the associations between skeletal and soft tissue features of the nasomaxillary complex and development and severity of obstructive sleep apnea (OSA) in adolescents. A total of 100 adolescents (mean age, 14.9 ± 1.4 years; age range, 13–17 years) were enrolled. All participants underwent full-night polysomnography and had an assessment of size and position of the tongue, tonsillar size, body mass index (BMI), and circumference of the waist, neck, and hip. The skeletal features of the nasomaxillary complex, including the zygomatic arch width, nasal cavity width, nasal base width, intercanine width, intermolar width, maxillary dental arch length, palatal vault angle, palatal depth, and SNA were measured on the three-dimensional images constructed with computed tomography data. Participants with an apnea and hypopnea index (AHI) of lower than 5 (AHI ≤ 5) were classified as control and participants while those with an AHI of greater than 5 were classified as OSA group. Each variable with a significant outcome in the independent T-test and age and sex factors were integrated into the multivariate linear regression and the dependent variable was AHI. There were significant differences in the BMI and hip circumference between two groups. The width of nasal base, palatal vault angle and SNA also showed significant differences between groups. The results from multivariate linear regression demonstrated that the BMI, width of the nasal base, and SNA showed significant contributions to the severity of OSA in adolescents. The features of the nasomaxillary complex seemed to have significant influences on development and severity of OSA.

Three-dimensional evaluation of pharyngeal airway and maxillary arch in mouth and nasal breathing children with skeletal Class I and II

ObjectiveThis study aimed to investigate whether the subjects with mouth breathing (MB) or nasal breathing (NB) with different sagittal skeletal patterns showed different maxillary arch and pharyngeal airway characteristics.MethodsCone-beam computed tomography scans from 70 children aged 10 to 12 years with sagittal skeletal Classes I and II were used to measure the pharyngeal airway, maxillary width, palatal area, and height. The independent t-test and the Mann–Whitney U test were used for the intragroup analysis of pharyngeal airway and maxillary arch parameters.ResultsIn the Skeletal Class I group, nasopharyngeal airway volume (P < 0.01), oropharyngeal airway volume (OPV), and total pharyngeal airway volume (TPV) (all P < 0.001) were significantly greater in subjects with NB than in those with MB. Furthermore, intermolar width, maxillary width at the molars, intercanine width, maxillary width at the canines, and palatal area were significantly larger in subjects with NB than in those with MB (all P < 0.001). In the Skeletal Class II group, OPV, TPV (both P < 0.05) were significantly greater in subjects with NB than in those with MB. No significant differences in pharyngeal airway parameters in the MB group between subjects with Skeletal Class I and those with Skeletal Class II.ConclusionRegardless of sagittal Skeletal Class I or II, the pharyngeal airway and maxillary arch in children with MB differ from those with NB. However, the pharyngeal airway was not significantly different between Skeletal Class I and II in children with MB.

Effect and stability of miniscrew-assisted rapid palatal expansion: A systematic review and meta-analysis.

ObjectiveThis study aimed to systematically analyze the effect and stability of miniscrew-assisted rapid palatal expansion (MARPE) to provide a reference for the clinical treatment of patients with maxillary transverse deficiency (MTD).MethodsWe searched PubMed, Science Direct, Web of Science, Embase, Cochrane Library, CNKI, and Wanfang Database for relevant studies published before February 18, 2021 and selected them according to the eligibility criteria. The Cochrane Handbook for Systematic Reviews (version 5.1.0) criteria were used for the quality assessment of randomized controlled trials, while the scoring protocol of the methodological index for non-randomized studies was used for non-randomized controlled trials. Statistical analysis was performed using the RevMan5.3 software.ResultsAll the included studies showed a relatively high success rate of expansion. The changes in both the intermolar and alveolar widths after MARPE were statistically significant. MARPE exhibited greater skeletal expansion effects than did conventional RPE. The midpalatal suture was opened in parallel after MARPE. A small amount of relapse was observed 1 year after expansion. MARPE caused tooth inclination and a decrease in alveolar height, but it was less significant than in conventional RPE.ConclusionsMARPE may be an effective treatment modality for patients with MTD. It causes great transverse skeletal expansion in late adolescence. In comparison to conventional RPE, MARPE has lower detrimental periodontal effects and has certain clinical advantages.

Dental arch form and arch dimensions among a group of Egyptian children and adolescents

BackgroundGrowth and development of the dental arch is considered a continuous and complex biological process. During transition from primary to mixed then to permanent dentition, dental arch form, length and width vary, due to tooth movement and vertical growth of alveolar process. These naturally occurring changes, which happen in untreated individuals, have been used as a comparative standard to assist in diagnosis and treatment planning of children with malocclusion. Therefore, the aim of the current study was to analyze dental arch dimensions in Egyptian children and adolescents with normal occlusion in primary, mixed, and permanent dentitions as well as detection of the most common forms of the dental arches among a group of Egyptian children and adolescents.ResultsResults showed that lower and upper arch lengths showed increase during transition from mixed to permanent dentition. A small increase in lower anterior arch length was recorded during transition from primary (4.63) to mixed dentition (4.70), while reduction of upper anterior arch length was observed during transition from primary (8.35) to mixed dentitions. An increase in anterior arch length was observed in both arches during transition from mixed to permanent dentitions (from 4.70 to 5.42 in the mandible and from7.92 to 9.90 in the maxilla). Arch perimeter, intercanine width, intermolar width increased in the upper and lower arches during transition between dentition till reaching the permanent dentition. It was also found that the ovoid arch form (58%) and square arch form (29%) were the most prevalent among Egyptian children and adolescents followed by the tapered arch form (13%).ConclusionsDental arch measurements of Egyptian children and adolescents can be used as a guide for treatment planning of Egyptian children and can be used in further studies to provide standard values for the arch dimensions of the Egyptian children. Regarding the arch form, the ovoid arch form was the most common among the Egyptian population followed by the square while the tapered arch form was the least common one.

Polygraphic evaluation of the effects of different rapid maxillary expansion appliances on sleep quality: A randomized clinical trial.

The purpose of this clinical study was to assess the effects of different rapid maxillary expansion appliances on the severity of obstructive sleep apnea (OSA). Patients having a narrow maxilla and identified with OSA were divided randomly into three groups: tooth tissue-borne, tooth-borne, and bone-borne expanders. Changes in sleep parameters at baseline and 3-month follow-up detected by polygraphy were the primary outcome. Treatment of the crossbite was the secondary outcome. Dunn-Bonferroni tests, Kruskal-Wallis, and Wilcoxon analysis were applied for intra- and inter-group differences at p < 0.05 significance level. Among 46 patients randomized, apnea-hypopnea index (AHI) changed from baseline to follow-up in all groups (- 1.6, p = 0.280; 0.6, p = 0.691; - 0.45, p = 0.796, respectively), with no between-group difference (p = 0.631). Oxygen desaturation index (ODI) altered from baseline to follow-up in all groups (0.80, p = 0.977; 0.20, p = 0.932; and - 1.00, p = 0.379, respectively), with no between-group difference (p = 0.858). There was no significant difference in minimum oxygen saturation from baseline to follow-up in all groups (0.00, p = 0.401; - 2.00, p = 0.887; 0.50, p = 0.407, respectively). No significant changes were observed in supine AHI from baseline to follow-up in all groups (0.00, p = 0.581; - 1.00, p = 0.393; 0.00, p = 0.972, respectively). The upper intermolar width increased from baseline to follow-up in all groups (5.04, p = 0.000; 3.15, p = 0.001; 5.41, p = 0.00, respectively) with no between-group difference (p = 0.560). Maxillary width increased from baseline to follow-up in all groups (4.25, p = 0.001; 4.74, p = 0.00; 4.49, p = 0.001, respectively) with no inter-group difference (p = 0.963). The amount of skeletal and dental expansion obtained in the maxilla was similar in all groups. Rapid maxillary expansion was not found to be effective in OSA treatment. ClinicalTrials.gov Identifier: NCT04604392.

Transverse digital dental analysis of patients treated with self ligating Damon Q system with different patterns of retention- A longitudinal study with three years follow up

The study aims to evaluate and compare the maxillary and mandibular intercanine, interpremolar, intermolars width of pretreatment, posttreatment and two years after treatment, in patients treated with the Damon Q bracket system. Further, to compare the arch width changes during 3 years of follow up, in patients under complete retention for 3 years and the cases under retention for 2 years. A sample of 60 patients treated with all four first premolar extraction, using Damon Q bracket system were selected from the Department of Orthodontics. The pre-treatment and post-treatment models were collected. Patients were divided into Group I with 2-year retention and Group II with 3 years retention. The patients of these groups were recalled after 3 years. The records were taken and the models were scanned using an intraoral scanner. The transverse widths between the canines, premolar and molars were measured through a third-party software. The parameters were compared, within the group at three-time intervals and between the groups.The intercanine width increased, whereas, the interpremolar and intermolar width decreased in both the groups after treatment. However, the comparison of the parameters from post treatment to follow up showed that in Group I the inter canine width decreased, but the interpremolar, and intermolar width increased, whereas, in group II the values remained almost the same. The parameters tend to revert to their original position once the retention is removed, whereas the cases under retention showed negligible changes in arch width.

Dental and Skeletal Characteristics and Behavioral Aspects of the Patient with Floating-Harbor Syndrome Compared with Twin Sister

Floating-Harbor syndrome (FHS) is a rare genetic disorder. This report introduced in a patient with FHS. Distinctive facial characteristics, severe skeletal class 3 malocclusion with underdeveloped maxilla and protruded mandible, congenital missing teeth, microdontia and ectopic positions of maxillary teeth were presented in the patient. In his twin sister, mild skeletal class 3 malocclusion with protruded mandible was observed but congenital missing teeth and microdontia were not observed. High-arched palate, narrow V-shaped maxillary arch compared to wide and ovoid mandibular arch and inverse relationship between the maxillary and mandibular intermolar width resulted in posterior crossbite were confirmed by model analysis of the patient. These were not observed in the twins. Behaviorally, poor cooperation during dental treatment because of mental retardation was observed in the patient.

Morphological Comparison of the Maxillary Arch in Buccal and Palatal Canine Impaction among Asian Population of Gujarati Origin: A Hospital-Based Study.

Aim: To estimate the differences in the maxillary arch morphology in buccal and palatal canine impaction in an Asian population of Gujarati origin. Methodology: An institutional ethics committee’s approval was acquired before the commencement of this study. Sixty subjects were enrolled in the study. Thirty subjects (20 females and 10 males) had a maxillary impacted canine either buccal or palatal and thirty control group participants were selected aged 13 to 18 years who sought orthodontic treatment at the tertiary health care center in Ahmedabad, Gujarat, in western India. Routine pre-treatment radiographs and dental plaster models with good anatomic details were recorded. Measurements of the inter-molar width, palatal depth, arch length, sum of the mesio-distal width of the upper incisors, and available arch space were recorded from prepared orthodontic study models using digital vernier calipers with an accuracy of 0.01 mm and brass wire. The ratio of palatal depth to inter-molar width (Ratio 1), arch length to inter-molar width (Ratio 2), and width of the maxillary incisors to available arch space (Ratio 3) were also secondarily calculated. Data were analyzed using Statistical Package for Social Sciences (SPSS) version 21, IBM Inc. The normality of the data was assessed by the Shapiro–Wilk test. As the data was found to be normally distributed, bivariate analyses were also performed (one-way ANOVA test, Bonferroni post hoc correction). The level of statistical significance was set at a p-value less than 0.05. Results: The comparison of the inter-molar width, palatal depth, arch length, sum of the mesio-distal width of the upper incisors, available arch space, Ratio 1, Ratio 2, and Ratio 3 among controls and subjects with buccal and palatal canine impaction showed overall significant differences in the inter-molar width, palatal depth, arch length, sum of the mesio-distal width of the upper incisors, and available arch space when compared using one-way ANOVA as p < 0.05. Ratios 1, 2, and 3 also showed significant differences between the buccal and palatal canine impaction. Conclusion: An inadequate arch length (p < 0.0001) and a higher degree of crowding with reduced available arch space (p < 0.0001) may be considered as early risk factors for buccal maxillary canine impaction. An inadequate inter-molar width (p < 0.0001), and an increased palatal depth (p < 0.0001) with a clinically reduced mesiodistal width of the sum of maxillary incisors may be considered as risk factors for palatal maxillary canine impaction in an Asian population of Gujarati origin.

Efficacy of fixed versus removal retianer post orthodontic treatment

The dearth of prolonged, prospective evaluation, the relative impact of fixed and the removable retainers eventualities can only be speculated upon. Hence in this study was to compare the stability of orthodontic outcomes with fixed and removable retainers over a period of at least 4 years. Of the 82 participants included in the previous RCT, data were obtained from 48 at 18-month follow up. Orthodontic stability was based chiefly on the irregularity of the mandibular incisors using Little’s Irregularity Index to assign a cumulative score for the contact point displacement in 4 the mandibular inter-canine region. Eighty-two participants were enrolled in the original RCT. After adjusting for confounders, the median between-groups difference was 1.64mm higher in those wearing vacuum-formed retainers (P= 0.02; 95% CI: 0.30, 2.98mm). No statistical difference was found between the treatment groups in terms of inter-canine (P= 0.52; 95% CI: -1.07, 0.55) and inter-molar widths (P= 0.55; 95% CI: -1.72, 0.93), arch length (P= 0.99; 95% CI: -1.15, 1.14) and extraction space opening (P= 0.84; 95% CI: -1.54, 1.86).

Maxillary Expansion: A Comparison of Damon Self-Ligating Bracket Therapy with MARPE and PAOO.

Purpose The aim of this study was to investigate arch parameters and dentoalveolar changes from pretreatment to posttreatment by comparing the Miniscrew Assisted Rapid Palatal Expansion (MARPE), Periodontally Accelerated Osteogenic Orthodontics (PAOO), and Damon self-ligating bracket therapies. Materials and Methods Seventy-nine patients underwent maxillary expansion followed by or in conjunction with Damon (n = 23), PAOO (n = 28), and MARPE (n = 28) therapies. Nine maxillary dental arch parameters were compared at pretreatment, posttreatment as well as, increments of treatment change. Measurements were made on STL study casts using 3Shape Ortho Analyzer 3D scanner software. Results All groups showed significant posterior width increase in the molar area. The mean increase in inter-molar distance was more than 8X greater in MARPE group compared to Damon and more than 4X greater compared to PAOO. MARPE showed significantly greater increments of change in inter-molar width and palatal vault area Conclusions All groups showed a significant width increase in the canine and molar area. MARPE showed the greatest increase in inter-molar width, followed by PAOO and Damon. MARPE was the only group to show a significant increase in palatal vault area.

Tongue Pressure Declines Early on in Patients with Malocclusion

(1) Background: The tongue plays a key role in the stomatognathic system in carrying out oral functions. The aim of this study was to identify the association between tongue pressure and orthodontic parameters. (2) Methods: This study is a cross-sectional multicentered cohort study with IRB approval. During routine orthodontic initial examinations, the following data were recorded: age, sex, angle classification, overjet (OJ), overbite (OB), arch sizes, tongue width, and maximum tongue pressure (MTP). The association between MTP and orthodontic parameters was analyzed using Pearson’s correlation analysis and the Student’s t-test. (3) Results: There is a positive correlation between MTP and age between ages 10 and 20 (R = 0.47, p &lt; 0.01). There is a negative correlation with MTP and age between 20 and 40 (R = −0.30, p &lt; 0.05). There are negative correlations between MTP and OJ (R = −0.278, p &lt; 0.01)) and OB (R = −0.374, p &lt; 0.01). While there is no statistical significance between MTP and tongue width, there is a statistically significant difference between age and tongue width (R = 0.22482, p &lt; 0.05). There is no statistical significance between MTP and sex, angle classification, arch length, intercanine width, and intermolar width. (4) Conclusion: An earlier decline in MTP is observed with patients with malocclusion. This implies that patients with malocclusion should seek early treatment for the malocclusion.

Error propagation from intraoral scanning to additive manufacturing of complete-arch dentate models: An in vitro study

ObjectivesTo evaluate deviation propagation from data acquisition with an intraoral scanner to additive manufacturing of complete-arch dentate models. MethodsA reference (Ref) mandibular dentate model having 5 precision spheres was scanned with a coordinate measurement machine equipped with a laser scanning head (ALTERA; Nikon) producing a Ni reference data set (n = 1). Digital impressions were taken of the Ref model with intraoral scanner (IOS) (Trios4; 3Shape) with Insane (T4_Imo) and Classic (T4_Cmo) scanning modes (each n = 10). T4_Imo scans were used as a second reference data set and to produce test models with two additive manufacturing (AM) devices (each n = 10): MAX UV385 (Asiga) and NextDent 5100 (3DSystems). As for the control group, dual viscosity vinyl polysiloxane impressions were taken of the Ref model and poured with Type IV dental stone (n = 10). All AM and stone models were scanned with a laboratory scanner (E4; 3Shape). Trueness and precision of linear (intermolar and intercanine width, arch length) and surface deviations were measured between reference (Ni, T4_Imo), test (T4_Cmo, AM), and control (stone) groups using best-fit alignments (Geomagic Control X; 3D Systems). The normality of data and differences between the groups were analyzed using Shapiro-Wilk, Levene's, Mann-Whitney U, Welch's t-test statistical analysis (p<0.05). ResultsThe accuracy of the IOS impression was not significantly affected by the scanning mode (p>0.05). Stone models showed significantly better trueness than IOS impressions (p<0.05). AM models had higher trueness than IOS Imo digital impressions (p<0.05). The precision of AM models was comparable (linear, p>0.05) or lower (surface, p<0.05) than of IOS Imo digital impressions. Trueness was insignificantly different among the stone and AM models (p>0.05). Higher trueness was achieved by Max UV385 than with Nextdent 5100 (p<0.05). The majority of linear and all surface deviations of IOS impressions and AM models were below 200 μm. ConclusionsWithin the limitations of this in vitro study, digital IOS impressions and AM models using the aforementioned equipment have acceptable accuracy for orthodontic and prosthodontic applications when complete-arch dentate records are used. Clinical SignificanceIOS and AM devices can have a significant influence on error propagation when applying digital workflow with complete-arch dentate models