Dental Occlusion Characteristics for Treatment Decision-Making Regarding Surgery-First Approach in Orthodontics

The surgery-first approach (SFA) is conducted to decrease the difficulty and duration of orthodontic treatment by correcting the skeletal discrepancy at the initial stage of treatment. However, the indication of the SFA has not been well defined yet. This study explored the dental occlusion characteristics for treatment decision-making regarding the SFA. A total of 200 skeletal Class III patients were consecutively collected and divided into two groups: the orthodontic-first approach (OFA) group and the SFA group. The pretreatment digital dental models and lateral cephalograms were measured. Logistic regression was completed and receiver operating characteristic (ROC) curves were obtained to predict the probability of the SFA. Results showed that the ROC model with L1-MP, upper and lower arch length discrepancy, overbite, and asymmetric tooth number as influencing factors revealed that the sensitivity and specificity for determining SFA were 83.0% and 65.0%, respectively; the accuracy of prediction was 75.0%. In conclusion, our findings indicate that the six measurements from digital dental models and lateral cephalograms can be effectively applied in treatment decision-making for the SFA with satisfactory accuracy.

Novel concept for posterior crossbite correction : Preliminary results

PURPOSE

The efficiency of dentoalveolar compensation involving both jaws for posterior crossbite correction using computer-aided design/computer-aided manufacturing (CAD/CAM) expansion and compression archwires was evaluated. Treatment outcome was tested against the null hypothesis that the transverse correction achieved would be significantly smaller than planned.

METHODS

This retrospective study included 64 patients (mean age 23.5 years, median 17.0, minimum/maximum: 9.0/63.0, standard deviation 13.7) with uni- or bilateral posterior crossbite. In all consecutively debonded patients, expansion and/or compression archwires were used for dentoalveolar correction involving both jaws. Plaster casts prior to (T1) and following treatment (T2) with completely customized lingual appliances (CCLA) were compared with the treatment plan represented by an individual target set-up. The statistical analysis was carried out using the Schuirmann TOST (two one-sided t‑tests) equivalence test on the basis of a one-sample t‑test with α = 0.025 to one side. The non-inferiority margin was set at δ = 0.5 mm.

RESULTS

All posterior crossbites could be corrected by dentoalveolar compensation involving both jaws. The mean total correction achieved was 6.9 mm (mean maxillary expansion: 4.3 mm/mean mandibular compression: 2.6 mm) with a maximum of 12.8 mm. The transverse corrections achieved in both arches at T2 were equivalent to the planned corrections in the set-up (p < 0.001).

CONCLUSION

The results of this study indicate that CAD/CAM expansion and compression archwires can be an efficient tool to achieve the desired correction in patients with a posterior crossbite even in more severe cases.

Comparative cephalometric evaluation of tongue position in subjects with skeletal class II division 1 and division 2 malocclusion

AIM AND OBJECTIVE

To evaluate and compare the position of the tongue from rest to centric occlusion in subjects with skeletal class II division 1 and skeletal class II division 2 malocclusions with subjects of skeletal class II normal occlusion.

MATERIAL AND METHODS

The study was conducted on 30 individuals equally divided into three groups of skeletal class II division (div) 1, skeletal class II div 2, and skeletal class I normal occlusion. The study was conducted on two lateral cephalograms for each subject: one taken at rest and one in centric occlusion.

RESULTS

On evaluation of tongue posture, a statistically significant difference was observed at the middle portion of the tongue in class II div 1 malocclusion, and at the posteromedial portion of the dorsum of the tongue in class II div 2 skeletal malocclusions as the tongue moved from rest to centric occlusion. While statistically significant differences were found between class II div 2 malocclusion and class I normal occlusion, no statistically significant differences were observed between class II div 1 and class II div 2 malocclusions.

CONCLUSION

Tongue position was observed to be the same in both class II div 1 and class II div 2 malocclusions, with no statistically significant differences. However, a great change was seen in the tongue position from rest to centric occlusion.

Vowel sound production and its association with cephalometric characteristics in skeletal Class III subjects

BACKGROUND

This study aimed to evaluate differences in vowel production using acoustic analysis in skeletal Class III and Class I Japanese participants and to identify the correlation between vowel sounds and cephalometric variables in skeletal Class III subjects.

MATERIALS AND METHODS

Japanese males with skeletal Class III (ANB < 0°) and Class I skeletal anatomy (0.62° < ANB < 5.94°) were recruited (n = 18/group). Acoustic analysis of vowel sounds and cephalometric analysis of lateral cephalograms were performed. For sound analysis, an isolated Japanese vowel (/a/,/i/,/u/,/e/,/o/) pattern was recorded. Praat software was used to extract acoustic parameters such as fundamental frequency (F0) and the first four formants (F1, F2, F3, and F4). The formant graph area was calculated. Cephalometric values were obtained using ImageJ. Correlations between acoustic and cephalometric variables in skeletal Class III subjects were then investigated.

RESULTS

Skeletal Class III subjects exhibited significantly higher/o/F2 and lower/o/F4 values. Mandibular length, SNB, and overjet of Class III subjects were moderately negatively correlated with acoustic variables.

LIMITATIONS

This study did not take into account vertical skeletal patterns and tissue movements during sound production.

CONCLUSION

Skeletal Class III males produced different /o/ (back and rounded vowel), possibly owing to their anatomical positions or adaptive changes. Vowel production was moderately associated with cephalometric characteristics of Class III subjects. Thus, changes in speech after orthognathic surgery may be expected. A multidisciplinary team approach that included the input of a speech pathologist would be useful.

Invisalign Treatment of a Three-Year-Old Child with Bilateral Posterior Scissor Bite and Multisite Upper Airway Obstruction: A Case Report

BACKGROUND

Scissor bites have been reported in relatively few epidemiological studies because of their extremely low prevalence rate (below 1%). The etiology of scissor bites remains obscure, but its impact on growth and function should not be ignored.

METHODS

In this case report, a novel treatment that utilizes Invisalign aligners was performed on a 3-year-old child who presented with a bilateral posterior scissor bite and anterior crossbite, accompanied by multisite obstruction in the upper airway. The aligners functioned as occlusion pads to unlock the scissor bite relationship and combined with cross-traction to narrow the maxillary arch and enlarge the mandibular arch simultaneously.

RESULTS

The duration of orthodontic therapy was 28 weeks. A multidisciplinary consultation (orthodontics department, ENT department, and spinal surgery) was conducted and a stable result was achieved. A healthy occlusal relationship, improved dental esthetics and a better lateral profile were eventually obtained.

CONCLUSIONS

Positive treatment outcomes rely on patients' good compliance in this case. In addition, we hope that clinicians will consider our situation in terms of alternative treatments and interprofessional experience.

Changes in hyoid bone and tongue position in Class I subjects after orthodontic treatment with rapid palatal expander

OBJECTIVE

To evaluate the effects of the rapid palatal expander (RPE) on the hyoid bone and tongue position in skeletal Class I patients, compared to control groups.

METHODS

Eighty-four Class I subjects, aged 6-14, were selected. Among these, 28 patients were treated with RPE, 28 with function-generating bite (FGB) appliance, and 28 were untreated. Lateral cephalograms taken before (T0) and after (T1) treatment were retrieved. Changes in the hyoid bone and tongue position were evaluated, and the area above the tongue was measured.

RESULTS

No significant difference in the hyoid and tongue posture was observed across the groups. However, there were significant differences for HC3 (distance from H-point to the third cervical vertebrae), H2H (distance from H-point to SN plane), and TT-Eb (tongue length) between T0 and T1 in all groups.

CONCLUSION

The results suggest that hyoid bone and tongue position changes were related to growth rather than treatment.

Oral Myofunctional and Articulation Disorders in Children with Malocclusions: A Systematic Review

BACKGROUND

Relationships between malocclusion and orofacial myofunctional disorders (OMD), as well as malocclusions and articulation disorders (AD) have been described, though the exact relationships remain unclear. Given the high prevalence of these disorders in children, more clarity is needed.

SUMMARY

The purpose of this study was to determine the association between OMD (specifically, bruxism, deviate swallowing, caudal resting tongue posture, and biting habits), AD, and malocclusions in children and adolescents aged between 3 and 18 years. To conduct a systematic review, 4 databases were searched (MEDLINE, Embase, Web of Science, and Scopus). The identified articles were screened for the eligibility criteria. Data were extracted from the selected articles and quality assessment was performed using the tool of Munn et al. [Int J Health Policy Manag. 2014;3:123-81] in consensus. Using the search strategy, the authors identified 2,652 articles after the removal of duplicates. After reviewing the eligibility criteria, 17 articles were included in this study. One of the included articles was deemed to have an unclear risk of bias, whereas all other articles were considered to have a low risk of bias. The articles showed a relationship between anterior open bite and apico-alveolar articulatory distortions, as well as between anterior open bite and deviate swallowing. For the biting habits, bruxism, and low tongue position no clear conclusions could be drawn. Key Messages: The current review suggests a link between specific types of malocclusion and OMD and AD. However, more high-quality evidence (level 1 and level 2, Oxford Levels of Evidence) is needed to clarify the cooccurrence of other OMD, AD, and malocclusions.

Comparative Analysis of the Differences in Dentofacial Morphology According to the Tongue and Lip Pressure

The aim of this study was to evaluate the effects of the tongue and lip pressure on dentofacial morphology. The subjects comprised 194 patients with malocclusion. Anterior and posterior tongue elevation and lip pressures were evaluated using the Iowa Oral Performance Instrument (IOPI) device. The lateral cephalograms of each subject were traced and digitized to perform the analysis. Statistical analysis was used to investigate the relationship between perioral muscle force and the cephalometric variables. Anterior and posterior tongue pressure was both higher in males than in females. No sex difference in lip pressure was observed. The group with a low posterior tongue pressure showed a short ramus height, short posterior facial height, and clockwise-rotated mandible. On the other hand, lip pressure had a significant influence on maxillary incisor angulation. Skeletal pattern was not found to be significantly related with lip pressure. The anterior tongue pressure appeared as a mixed pattern of the two results. Tongue pressure was related to skeletal measurements, such as short posterior facial height, and lip pressure was related to the angulation of the anterior teeth. This study suggests that there may be differences in dentofacial morphology according to the differences in perioral muscle force.

Classification and Morphological Analysis of the Hard Palate in Cone-Beam Computed Tomography Scans: A Retrospective Study

PURPOSE

As the hard palate is a central structure of the skull and is involved in orthodontic and surgical procedures, it would be of interest to study the morphological aspects of this bone and its possible variations as per different patterns of skeletal development. Thus, this study aimed to develop a classification for the different morphological characteristics of the hard palate and to evaluate the relationship between these characteristics and the different skeletal patterns, using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This retrospective and cross-sectional study used CBCT scans of patients seen from January 2014 to December 2016. Carestream Dental 3D Imaging software was applied to classify each patient according to vertical and sagittal skeletal patterns, and to evaluate the 3 morphological characteristics of the hard palate: depth (flat, regular, or deep), inclination (superior, parallel, or inferior), and presence of a bony projection (S-shaped). χ² and Fisher's exact tests evaluated the relationship between the hard palate characteristics and the different skeletal patterns.

RESULTS

A total of 298 CBCT scans (144 males and 154 females) were evaluated. The depth of the hard palate was significantly related to both skeletal patterns in males (P < .05), with Class II and dolichocephalics presenting a greater amount of deep palates, while classes I and III and brachycephalics had a greater amount of regular palates. The inclination of the hard palate was significantly associated with the facial type in females (P < .05), with brachycephalics and mesocephalics presenting a greater amount of parallel palates, whereas dolichocephalics had a greater number of inferiorly inclined palates. Regarding the presence of the S-shape in the hard palate, there was a greater number of this projection in Class II males and brachycephalic females.

CONCLUSIONS

A morphological classification for the hard palate was developed. The morphology of the hard palate varied among the different skeletal patterns.

The assessment of resting tongue posture in different sagittal skeletal patterns

INTRODUCTION

Resting tongue posture affects the surrounding structures and, theoretically, may result in altered arch form and jaw relationship.

OBJECTIVE

The objective of the present study was to investigate the association between resting tongue posture as observed in lateral cephalometric radiograph, sagittal jaw relationship and arch form.

METHODS

The study was conducted on pretreatment lateral cephalograms and dental casts of 90 subjects. Subjects were equally divided into three groups, based on sagittal jaw relationship (Class I, II and III). Tongue posture was determined in terms of tongue-to-palate distances at six different points (distances 1 to 6) using ViewPro-X software, according to the method described by Graber et al in 1997. The arch widths (intercanine and intermolar widths) were evaluated on pretreatment dental casts.

RESULTS

Tongue-to-palate distances were found to be comparable among different study groups. Significant differences were found in intercanine and intermolar widths at the cuspal and gingival levels among the study groups, except for intercanine width at cuspal level in maxilla and intermolar width at cuspal level in mandible. Moderate positive correlation was found between arch widths ratios at distances 3 and 4 in skeletal Class III group. Effect size was found to be moderate to large in different sagittal skeletal patterns and arch widths.

CONCLUSION

The results of the current study showed no significant differences in the resting tongue posture among the groups, and moderate to weak correlation between tongue posture and dental arch widths.

Differential Diagnosis of Skeletal Class III

Skeletal Class III is a relatively rare malocclusion of the craniofacial complex and the accurate differential diagnosis of its aetiology is necessary so that it may be correctly treated. Differential diagnosis of Class III aetiopathogenesis should distinguish between: a) true skeletal Class III as opposed to pseudo Class III; b) three forms of Skeletal Class III, in which there is either maxillary deficiency only or mandibular excess only or combination of both; and c) skeletal Class III that may be treated with orthodontic treatment alone, as opposed to Class III that is difficult to manage with orthodontic treatment alone and requires combine orthodontic and surgical approach. Differential diagnosis is mainly based on clinical examination and cephalometric analysis. The aim of this paper is to present the basic principles and modes of achieving differential diagnosis in skeletal Class III cases.

The association between palatal rugae pattern and dental malocclusion

Introduction:

Palatal rugae complete its development during early intrauterine life, whereas dental malocclusions in permanent dentition establishes several years into the post-natal life.

Objective:

The objective of present study was to determine if there is an association between the palatal rugae pattern and Angle’s classes of malocclusion.

Methods:

A cross-sectional study was conducted on pretreatment dental casts of 184 patients. The sample was divided into the following groups: Class I, Class II div. 1, Class II div. 2, and Class III. The number of palatal rugae was recorded, bilaterally. The length, pattern and orientation of three anterior-most primary rugae on both sides were recorded.

Results:

The mean age of the study sample was 17.8 ± 5.4 years. The mean number of the palatal rugae was 11.18 ± 2.5, with significant differences among different malocclusion groups. The length of the first rugae on left side and third rugae on both sides varied significantly among the groups (p< 0.05). Similarly, the pattern of palatal rugae was also found to be significantly different among the malocclusion groups. The right sided rugae did not have any significant difference in the orientation in different malocclusion groups; however, the left sided rugae showed significant differences among the four malocclusion groups (p< 0.001).

Conclusions:

The current study showed subtle differences in the palatal rugae pattern among the Angle’s classes of malocclusion. Similarly, the length and orientation of some rugae were also found to be significantly different between malocclusion groups.

Relationship between tongue pressure and maxillofacial morphology in Japanese children based on skeletal classification

During childhood, perioral muscle function is closely associated with malocclusion. To clarify the effects of tongue function on maxillofacial morphology in children, tongue pressure and maximum lip-closing force (LCF) were measured and the relationship between perioral muscle function and maxillofacial morphology was evaluated according to the skeletal classification. Maximum tongue pressure (MTP) and swallowing tongue pressure (STP) were measured on the anterior palatine rugae in 100 children (Hellman's dental stages IIIA-IIIC) using a balloon-type tongue pressure measurement device. Lip-closing force was measured using an LCF measurement device. Lateral cephalograms were examined to classify subjects into skeletal (S)-I, S-II and S-III groups. Correlations of skeletal classification with tongue pressure and LCF were examined. Correlations of lateral cephalometric measurements with palatal volume (PV), measured using a three-dimensional optical scanner, were evaluated. Maximum tongue pressure was significantly lower in the S-II group than in other groups. Swallowing tongue pressure was significantly lower in the S-II group than in the S-III group. Lip-closing force was significantly higher in the S-III group than in other groups. Swallowing tongue pressure was positively correlated with MTP and PV. Correlations between tongue pressure and anteroposterior skeletal classification indicated the importance of quantitative tongue function assessment.

Evaluations of the tongue and hyoid bone positions and pharyngeal airway dimensions after maxillary protraction treatment

OBJECTIVE

To assess changes in the tongue and hyoid bone positions and airway dimensions after maxillary protraction using lateral cephalograms.

METHODS

Lateral cephalograms were obtained before (C0) and after (C1) an observation period for untreated children with skeletal Class I malocclusion and before (T0), immediately after (T1), and one year after (T2) maxillary protraction in children with skeletal Class III malocclusion. Cephalometric measurements were compared between the time points in both patient groups.

RESULTS

Immediately after maxillary protraction, the tongue moved superiorly and the nasopharyngeal and superior oropharyngeal airway dimensions increased. No significant changes in the middle or inferior oropharyngeal airway dimensions or in the hyoid bone position were noted after treatment.

CONCLUSIONS

Maxillary protraction improved tongue posture and modified the nasopharyngeal and superior oropharyngeal airway dimensions in patients with skeletal Class III malocclusion. Consequently, maxillary protraction may restore the intra- and extraoral balance and improve respiratory function.

Relationships among nasal resistance, adenoids, tonsils, and tongue posture and maxillofacial form in Class II and Class III children

INTRODUCTION

The purpose of this study was to clarify the relationships between upper airway factors (nasal resistance, adenoids, tonsils, and tongue posture) and maxillofacial forms in Class II and III children.

METHODS

Sixty-four subjects (mean age, 9.3 years) with malocclusion were divided into Class II and Class III groups by ANB angles. Nasal resistance was calculated using computational fluid dynamics from cone-beam computed tomography data. Adenoids, tonsils, and tongue posture were evaluated in the cone-beam computed tomography images. The groups were compared using Mann-Whitney U tests and Student t tests. The Spearman rank correlations test assessed the relationships between the upper airway factors and maxillofacial form.

RESULTS

Nasal resistance of the Class II group was significantly larger than that of the Class III group (P = 0.005). Nasal resistance of the Class II group was significantly correlated with inferior tongue posture (P <0.001) and negatively correlated with intermolar width (P = 0.028). Tonsil size of the Class III group was significantly correlated with anterior tongue posture (P <0.001) and mandibular incisor anterior position (P = 0.007). Anterior tongue posture of the Class III group was significantly correlated with mandibular protrusion.

CONCLUSIONS

The relationships of upper airway factors differ between Class II and Class III children.

Patterns of morphological integration in the dental arches of individuals with malocclusion

OBJECTIVES

In humans, there is a large range of variation in the form of the maxillary and mandibular dental arches. This variation can manifest as either prognathism or retrognathism in either or both arches, which can cause malocclusion and lead to abnormal masticatory function. This study aims to identify aspects of variation and morphological integration existing in the dental arches of individuals with different types of malocclusion.

METHODS

Coordinate landmark data were collected along the gingival margins of 397 scanned dental casts and then analyzed using geometric morphometric techniques to explore arch form variation and patterns of morphological integration within each malocclusion type.

RESULTS

Significant differences were identified between Class II forms (increased projection of upper arch relative to the lower arch) and Class III forms (lower arch projection beyond the upper arch) in symmetrical shape variation, including anteroposterior arch discrepancies and abnormal anterior arch divergence or convergence. Partial least squares analysis demonstrated that Class III dental arches have higher levels of covariance between upper and lower arches (RV = 0.91) compared to the dental arches of Class II (RV = 0.78) and Class I (RV = 0.73). These high levels of covariance, however, are on the lower end of the overall range of possible masticatory blocks, indicating weaker than expected levels of integration.

CONCLUSIONS

This study provides evidence for patterns of variation in dental arch shape found in individuals with Class II and Class III malocclusions. Moreover, differences in integration found between malocclusion types have ramifications for how such conditions should be studied and treated. Am. J. Hum. Biol. 28:879-889, 2016. © 2016Wiley Periodicals, Inc.

Diagnosis of Class III malocclusion in 7- to 8-year-old children--a 3D evaluation

OBJECTIVES

The aim of this study was to characterize facial and jaw morphology of children with Class III malocclusion in early mixed dentition.

METHODS

This study was conducted on 7- to 8-year-old Caucasian children, 48 children with Class III malocclusion and 91 children with normal occlusion. Surface images of faces and study casts were obtained using laser scanning. Two average facial templates were constructed for the males and females in the control group. The facial images were superimposed on the corresponding average templates. Facial parameters, palatal volumes, and gingival surface areas were measured and group differences were quantified. The analysis of variance was used for statistical evaluation of the measured parameters.

RESULTS

The results revealed shorter lower face height (P < 0.001), concave facial profile (P < 0.001), retruded maxilla (P < 0.001), protruded mandible (P < 0.001), retrusive mid-face restricted area (P < 0.001), reduced gingival surface area of the maxilla (P = 0.013), and reduced maxilla/mandible gingival surface area ratio (P < 0.001) in the Class III group compared to the control group. There were no differences between the groups in upper face height, restricted areas of the upper and lower face, palatal volume, and gingival surface area of the mandible (P > 0.05).

LIMITATIONS

Regardless of the fact that the prevalence of Class III malocclusion is rather small, the sample size could be larger.

CONCLUSIONS

Class III subjects show clinically relevant facial and jaws characteristics in pre-pubertal growth period. A comprehensive diagnosis should include transverse dimension analysis.

Possible causal relationships between competitive swimming in growing age and three-dimensional dentoalveolar development

Background

The aim of this study was to investigate possible links between competitive swimming during the growth phase and the development of the dentoalveolar arches.

Methods

The study sample included 100 swimmers and a control group of 100 age-matched non-swimmers who had never practised swimming or related sports. Subjects who had had previous orthodontic treatment were excluded. Overjet, overbite, sagittal and transverse parameters, arch dimension, crowding and oral habits were recorded.

Results

In the swimmers, there was a significantly higher frequency of molar symmetry (P = 0.04), together with a greater number of Class I subjects. The overjet in the swimmers was mainly normal, but the arch dimensions were significantly wider (+10% in the upper arch; P < 0.001). Similarly, the swimmers showed significantly less severe crowding (P < 0.001) and significantly reduced oral habits (P < 0.001).

Conclusions

Our data and analysis demonstrate that competitive swimming during the growth phase has a favourable effect on dental arch development in the sagittal, vertical and transverse planes.