Diagnostic methods for assessing maxillary skeletal and dental transverse deficiencies: A systematic review

Credibility of Pont's index in Egyptian population

BACKGROUND

Many indices have been suggested to help orthodontists in predicting the ideal dental arch width. One of these was Pont's index which was established by Pont. He suggested equations to predict the ideal maxillary dental arch width (interpremolar and intermolar) from the combined mesiodistal width of the maxillary incisors. This study aimed to test the applicability of Pont's index as an orthodontic diagnostic tool in Egyptian population and to compare the results with those obtained from studies of different ethnic subjects.

METHODS

This study was performed using dental casts of 184 Egyptian individuals (82 males and 102 females; age range, 19-24 years). The casts were divided into 46 casts with normal occlusion, 46 casts with class I, 46 casts with class II and 46 casts with class III malocclusion, according to Angle's classification. Alginate impressions were taken for all patients and poured immediately using dental plaster. The real models were transformed into digital models using three-dimensional laser scanner to allow digital model analysis. Predicted arch widths were calculated using Pont's equations. The predicted values were compared to the measured values.

RESULTS

Intra class correlation coefficient (ICC) (absolute agreement) between measured and predicted arch widths was determined. Poor absolute agreement was found between measured arch width values and the corresponding values calculated according to Pont's index.

CONCLUSION

According to the results of this study, Pont's index is not a reliable method for predicting the ideal dental arch widths in Egyptian populations.

Midpalatal Suture Maturation in Relation to Age, Sex, and Facial Skeletal Growth Patterns: A CBCT Study

BACKGROUND

The evaluation of midpalatal suture maturation is essential to undertake the most predictable maxillary expansion approach. Several factors, such as age, gender, and facial growth patterns, seem to be involved in midpalatal suture staging and, consequently, in its opening; however, the link between these variables and the stages of midpalatal suture development remains poorly understood. Our study aimed to analyse the midpalatal suture maturation in relation to age, sex, and skeletal growth patterns by CBCT.

METHODS

We enrolled 263 patients (119 males and 144 females) aged from 8 to 20 years. The midpalatal suture maturation was defined according to Angelieri et al.'s classification using a low-dose CBCT. The chi-square test and linear regression were applied to investigate the suture stages by age, sex, and vertical and sagittal growth patterns.

RESULTS

Stage A was present in 8- and 9-year-olds with a larger prevalence in boys, while the prevalence of stage E increased progressively with age. Stage D was the most prevalent in our sample. The statistical analysis described that stage A was more likely in the youngest subjects, and stage E in the oldest participants. The males tended to have lower maturation stages. Moreover, the hypodivergent and normodivergent subjects tended to have higher maturation stages, while Class III was more likely in subjects in stages D or E.

CONCLUSIONS

A total of 127 patients were in stages A, B, and C, showing an unfused suture. In young individuals, the opening of the midpalatal suture leads to a proper facial growth development by correcting the transverse superior hypoplasia. The midpalatal sutural maturation classification was related to age, sex, and divergence.

Functional therapy and adenotonsillectomy clinical trial for class II malocclusion (FACT-II): protocol for a randomised controlled trial

INTRODUCTION

Class II malocclusion with mandibular retrognathia is a common complication of paediatric obstructive sleep apnoea (OSA), often accompanied by transverse maxillary deficiency. In early orthodontic treatment, a twin block (TB) is a regular functional appliance for correcting this malocclusion. For paediatric OSA, the most common risk factor is adenotonsillar hypertrophy (AHT). Untreated AHT may lead to the persistence and worsening of obstructive sleep-disordered breathing traits, including habitual mouth breathing. Additionally, the clockwise mandibular rotation associated with AHT-induced pharyngeal crowding can undermine the effectiveness and stability of TB treatment. Adenotonsillectomy (T&A) is currently the first-line treatment for paediatric OSA. This proposed trial will investigate the impact of T&A surgery timing on the efficacy and stability of TB functional treatment in children with class II mandibular retrognathia and ATH.

METHODS AND ANALYSIS

This will be a single-centre, parallel-group, superiority randomised controlled trial with participants randomised to intervention (T&A followed by TB treatment) or control arms (TB treatment followed by T&A) in a 1:1 ratio. A total of 40 patients aged 8-14 years, diagnosed with class II mandibular retrognathia and co-existing ATH-induced OSA, and indicated for both T&A surgery and TB treatment, will be recruited at the School and Hospital of Stomatology, Wuhan University. The primary outcomes will be the changes in the apnoea-hypopnoea index and the point A-nasion-point B angle from baseline to postorthodontic treatment between the two groups. Secondary outcomes will include other dental, skeletal, upper airway and soft tissue changes, as well as subjective sleep-related and oral-related quality of life. Outcome changes within each group and between groups will be analysed.

ETHICS AND DISSEMINATION

This study is approved by the Ethics Committee of the School and Hospital of Stomatology, Wuhan University (no. 2022-D07). The research findings will be faithfully disseminated through scientific conferences or published articles.

TRIAL REGISTRATION NUMBER

ChiCTR2200061703 (https://www.chictr.org.cn).

Association between nasal septum deviation and transverse maxillary development: A retrospective cross-sectional study

INTRODUCTION

The few studies investigating the relationship between nasal septum deviation (NSD) and maxillary development, using different assessment methods and the age of subjects, reported contradicting results.

METHODS

The association between NSD and transverse maxillary parameters was analyzed using 141 preorthodontic full-skull cone-beam computed tomography scans (mean age, 27.4 ± 9.01 years). Six maxillary, 2 nasal, and 3 dentoalveolar landmarks were measured. The intraclass correlation coefficient was used to assess intrarater and interrater reliability. The correlation between NSD and transverse maxillary parameters was analyzed using the Pearson correlation coefficient. Each transverse maxillary parameter was compared among 3 groups of different degrees of severity using the analysis of variance test. Transverse maxillary parameters were also compared between the more and less deviated nasal septum sides using the independent t test.

RESULTS

A correlation between deviated septal width and palatal arch depth (r = 0.2, P <0.013) and significant differences in palatal arch depth (P <0.05) among 3 NSD severity groups classified with deviated septal width was noted. There was no correlation between septal deviated angle and transverse maxillary parameters and no significant difference for transverse maxillary parameters among the 3 groups of NSD severity classified by septal deviated angle. No significant difference in transverse maxillary parameters was found when comparing the more and the less deviated sides.

CONCLUSIONS

This study suggests that NSD can affect palatal vault morphology. The magnitude of NSD may be a factor associated with transverse maxillary growth disturbance.

Maxillary transverse deficiency diagnosed by 3 methods and its relationship with molar angulation in patients with skeletal Class III malocclusion

INTRODUCTION

The objective of this study was to evaluate the relationship between maxillary transverse deficiency (MTD) diagnosed by 3 methods and molar angulation measured in 3-dimensions in patients with skeletal Class III malocclusion, which could give reference to the selection of diagnostic methods in MTD patients.

METHODS

Cone-beam computed tomography data of 65 patients with skeletal Class III malocclusion (mean age 17.35 ± 4.45 years) were selected and imported into MIMICS software. Transverse deficiencies were evaluated by 3 methods, and molar angulations were measured after reconstructing 3-dimensional planes. Two examiners performed repeated measurements to assess the intraexaminer and interexaminer reliability. Pearson correlation coefficient analyses and linear regressions were performed to determine the relationship between a transverse deficiency and molar angulations. One-way analysis of variance was used to compare the diagnostic results of 3 methods.

RESULTS

The novel molar angulation measurement method and 3 MTD diagnostic methods have the interexaminer and intraexaminer intraclass correlation coefficient values >0.6. The transverse deficiency diagnosed by 3 methods was significantly and positively correlated with the sum of molar angulation. There was a statistically significant difference for the transverse deficiencies diagnosed by the 3 methods. The transverse deficiency was significantly higher in Boston University's analysis than in Yonsei's analysis.

CONCLUSIONS

Clinicians ought to choose the diagnostic methods properly, considering the feature of the 3 methods and the individual difference of each patient.

A novel maxillary transverse deficiency diagnostic method based on ideal teeth position

BACKGROUND

This study proposed a novel maxillary transverse deficiency diagnostic method and evaluated the skeletal Class I and the mild skeletal Class III groups.

METHODS

Pre-treatment data from 30 mild skeletal Class III and 30 skeletal Class I patients were collected and uploaded to the Emeiqi Case Management System to design the ideal teeth positions. On these positions, the first bi-molars width was measured at the central fossa and center resistance, the maxillary first bi-premolars width was measured at the central fossa, and the mandibular first bi-premolars width was measured at the distal contact point by Mimics, then width differences of two groups were calculated respectively.

RESULTS

At ideal teeth positions, there was no statistically significant difference in the maxillomandibular width in the premolar area between the two groups, but there was in the molar area, and this difference was caused by the difference in mandible width between the two groups.

CONCLUSIONS

We proposed a new transverse diagnostic method and found that even the Class I group was not quite up to standard in the molar area on ideal teeth positions, and the Class III group had more severe maxillary transverse deficiency than the Class I group. Meanwhile, the maxillary transverse deficiency in the Class III group was mainly caused by the larger width of the mandible.

Effects on Muscular Activity after Surgically Assisted Rapid Palatal Expansion: A Prospective Observational Study

The study aims to investigate the modifications in the temporalis and the masseter activity in adult patients before and after SARPE (Surgically Assisted Rapid Palatal Expansion) by measuring electromyographic and electrokinesographic activity. 24 adult patients with unilateral posterior crossbite on the right side were selected from the Orthodontic Department of the University of Milan. Three electromyographic and electrokinesographic surface readings were taken respectively before surgery (T0) and 8 months after surgery (T1). The electromyographic data of both right and left masseter and anterior temporalis muscles were recorded during multiple tests: standardized maximum voluntary contraction (MVC)s, after transcutaneous electrical nerve stimulation (TENS) and at rest. T0 and T1 values were compared with paired Student’s t-test (p < 0.05). Results: Significant differences were found in the activity of right masseter (p = 0.03) and right temporalis (p = 0.02) during clench, in the evaluation of right masseter at rest (p = 0.03), also the muscular activity of masseters at rest after TENS from T0 to T1 (pr = 0.04, pl = 0.04). No significant differences were found in the activity of left masseter (p = 0.41) and left temporalis (p = 0.39) during clench and MVC, in the evaluation of left masseter at rest (p = 0.57) and in the activity during MVC of right masseter (p = 0.41), left masseter (p = 0.34), right temporalis (p = 0.51) and left temporalis (p = 0.77). Results showed that the activity of the masseter and temporalis muscles increased significantly after SARPE during rest and clenching on the side where the cross-bite was treated.

A New Approach to Diagnosis to Posterior Cross Bite: Intraoral Photography and Wala Ridge

A posterior crossbite is an occlusion disorder that occurs in the transverse plane. It occurs when the buccal cusps of the upper premolars and molars engage lingually with the buccal cusps of the lower teeth. It can be unilateral or bilateral (involving one or more teeth) in the primary, mixed, or permanent dentition. A crossbite may appear in early dentition stages and it can be dental or functional. It can lead to skeletal crossbite in mixed dentition. Therefore, early diagnosis and treatment are crucial. Material and methods: The selected sample included 204 patients in growing stage divided into two groups: a study group of 102 patients with posterior crossbite and a control group of 102 patients without malocclusion. To analyze the pathology, intraoral frontal photographs and study models were taken, in which the bone component was measured from the Wala Ridge. Results: The use of the photographs to study the Wala Ridge was confirmed. The mean maxillary width was 57.8 mm (SD 1.7) and mandibular width was 56.4 mm (SD 1.7) for the control group, with a maxillomandibular difference of 1.4 mm (SD 0.7); and 52.7 mm (SD 3.7) and 55.5 mm (SD 3.6), respectively, with a maxillomandibular difference of −2.8 mm (SD 1.4) for the study group. A higher maxillomandibular discrepancy was observed in patients with a posterior crossbite that involved more than one tooth in addition to the permanent first molar. It was also higher in patients with bilateral posterior crossbite. Conclusions: Intraoral frontal photography can be used as a diagnostic method to measure the maxillomandibular difference using the Wala Ridge.

An evaluation of three-dimensional facial changes after surgically assisted rapid maxillary expansion (SARME): an observational study

BACKGROUND

The abnormal facial features in maxillary transverse deficiency (MTD) are minimal and limited to a deficiency of the middle facial third, narrow nares and nasal base, and deepened nasolabial folds. The surgical expansion of the narrow maxilla has most obvious effects on widening of the maxillary dental arch and expansion of the maxillary and palatal structures in the transverse plane, however sagittal changes also occurs. The purpose of this observational study was to evaluate the three-dimensional (3D) facial soft tissue changes following surgically assisted rapid maxillary expansion (SARME).

METHODS

In 15 skeletally mature patients with severe maxillary transverse deficiency, the planned maxillary expansion (on average 8.8 mm ± 2.3 mm) was achieved with a bone-borne palatal distractor. The 3D optical scans of the facial surface were obtained before and six months after SARME. In the first part, we defined different anatomical landmarks on both scans and compared cephalometric measurements. In the second part, we registered both 3D scans in the same workplace using the regional best-fit method (forehead, supraorbital and nasal root regions were selected for the superimposition) and conducted surface analysis.

RESULTS

The largest differences between the pre- and post-operation scans were observed in the paranasal and cheek area (1.4 ± 1.0 mm). Significant differences occurred for an increased nasal width, a decreased upper-face height with an unchanged lower height, an increased vertical philtrum height and an increased nasolabial angle. A significant increase in the facial profile angle was also observed, resulting in an increased facial convexity and anterior displacement of the upper-lip area.

CONCLUSIONS

The widening of the nose and increased projection in the cheek and paranasal area in the lateral direction after maxillary expansion were confirmed; moreover, facial convexity increases, reflecting the underlying advancement of the maxilla.

Testing the Accuracy of Pont’s Index in Diagnosing Maxillary Transverse Discrepancy as Compared to the University of Pennsylvania CBCT Analysis

Assessment of maxillary transverse discrepancy requires an accurate tool in order to implement the appropriate treatment plan. Aim: To evaluate the accuracy of Pont’s Index in confirming a transverse maxillary deficiency by comparing its results with the corresponding results yielded by the University of Pennsylvania CBCT analysis. Material and methods: The study was performed on dental casts and CBCT’s of 60 randomly selected patients by adopting a cluster sampling method. The results of Pont’s Index and University of Pennsylvania CBCT analysis were analyzed through McNemar’s test using Excel Data Analysis, and the accuracy indicators for Pont’s Index were computed using MedCalc Ltd. Results: Mc Nemar’s test revealed a p-value of 0.85. The accuracy indicators of Pont’s Index were: sensitivity: 69%; specificity: 16.6%; positive predictive value: 65%; negative predictive value: 18.75%; positive likelihood ratio: 0.83; negative likelihood ratio: 1.86; and accuracy: 53.28%. Conclusion: Due to the fact that CBCT is not used on a daily basis and Pont’s Index has a relatively high sensitivity (69%) making it suitable to detect patients with a narrow maxilla, assessment of the maxillary deficiency on CBCT can be recommended for cases were the midpalatal suture maturation should be evaluated.

Surgically assisted rapid palatal expansion for transverse maxillary discrepancy in adults - Case report

Introduction and importance

Transverse maxillary deficiency is one of the most detrimental problems to midfacial growth and the integrated dentoalveolar structures. Early diagnosis and proper treatment of such cases is most important to maintain the balance between the basal bones and stable occlusion.

Case presentation

In our case, a 17-year-old male had irregular upper front teeth with an unpleasant smile. Detail examination revealed a symmetrical face with an orthognathic profile, mild malar deficiency, competent lips, asymmetrical arches, Class I molar and canine relationships bilaterally. Crowding was present in the upper anterior arch with 2 mm of anterior open bite and posterior cross bite present in the premolar region and molar region bilaterally. Lefort-1 osteotomy, midpalatal split, pterygomandibular disjunction without down fracture was done. The HYRAX appliance was cemented. Distraction started after four days of surgery. One mm distraction per day was done for 10 days. The patient was transferred to fixed orthodontic treatment to relive the anterior crowding. Records were taken after 1 year of follow up and analyzed. Skeletal relationships were in harmony. Dental crowding, anterior open bite and posterior crossbite were corrected.

Clinical discussion

The zygomatic buttress and the pterygomaxillary junction are considered as the critical areas of resistance for maxillary expansion. Literature claims lefort-1 osteotomy in combination with palatal distraction results in more displacement and less stress in the maxilla.

Conclusion

SARPE has proved to be clinically effective and stable for the correction of transversely deficient maxilla after cessation of growth in adult patients.

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Maxillary skeletal base is retrognathic but facial profile is orthognathic. But only transverse discrepancy was treated.

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Among orthognathic surgery, SARPE is rare and is indicated when only transverse discrepancy needs to be addressed.

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Orthognathic surgery is done in 3 stages. We did surgery-first approach here, thus only two stages of treatment was required.

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Soft tissue compensation is also taken into consideration along with position of skeletal base of maxilla.

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Complete orthodontic treatment requires about two years’ time but this SARPE case has been completed in one year.

The Diagnosis Methods and Management Modalities of Maxillary Transverse Discrepancy

Transverse deficiency of the maxilla (TDM) is the most common skeletal change that involves the maxilla. The craniofacial skeletal assessment as early as possible is critical, as the early diagnosis of TDM influences the effectiveness of treatment. Methods for treating TDM have been reported since the mid-19th century and continue to evolve. This article puts forward a literature review on the topic, investigating the diagnosis and management of TDM, as well as stability after surgical and nonsurgical interventions. We conducted a literature search using a logical combination of the terms “palatal extension,” “maxillary transverse deficiency,” “diagnosis,” and “management.” More recent approaches include three-dimensional imaging, which has allowed for accurate depictions of the craniofacial region to be examined, allowing for evaluation of the spatial relationships between the jaw elements. The success of nonsurgical management compared to surgical management depends on the growth stage of the patient. Unfortunately, data comparing the stability of surgical and nonsurgical management is still lacking. However, for surgical intervention, surgically assisted palatal expansion (SARPE) appears to be the appropriate choice, especially when a large expansion is needed.

Correlations Between Mandibular Asymmetries and Temporomandibular Disorders: A Systematic Review

Objective

This systematic review aimed to investigate the correlation between mandibular asymmetry and temporomandibular disorders (TMDs).

Materials and Methods

A systematic search of the published literature was performed in electronic databases such as PubMed (MEDLINE), Scopus, Web of Science, Cochrane, Google Scholar, Clinicaltrials.gov, and Saudi Digital Library. Gray literature was searched through System for Information on Grey Literature through OpenGrey. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed in the investigation. The focussed question according to PICO format was: "does the mandibular asymmetry contribute to temporomandibular disorders"? Eligibility criteria included clinical trials (CTs), observation studies, cross-sectional and cohort studies in English that investigated mandibular asymmetries and TMD among patients. Blind and duplicate study selection, data extraction, and risk of bias assessment were carried out.

Results

The initial search resulted in 1906 articles, of which 11 (8 CTs, 1 cross-sectional, 1 retrospective, and 1 observational) studies were selected for qualitative synthesis after fulfilling the eligibility criteria.

Conclusion

Most of the studies included in this review showed either very high risk or high risk of bias. Despite the low certainty of evidence, the current study indicated a likely relationship between mandibular asymmetries and TMDs.

Correlation between the transverse dimension of the maxilla, upper airway obstructive site, and OSA severity

STUDY OBJECTIVES

Acquiring a better comprehension of obstructive sleep apnea physiopathology can contribute to improving patient selection for surgical treatments. We hypothesize that maxillary transverse deficiency restricts the space available for the tongue, leading to upper airway obstruction during sleep. Our primary hypothesis was that maxillary transverse deficiency increases the prevalence of tongue collapse during drug-induced sleep endoscopy (DISE). The secondary hypothesis was that maxillary transverse deficiency will also increase the prevalence of circumferential collapse at the velopharynx. The exploratory hypothesis was that maxillary transverse deficiency is associated with increased obstructive sleep apnea severity. The objectives of this study were to correlate maxillary morphometric measurements with (1) the anatomic level of obstruction during DISE and (2) the apnea-hypopnea index on polysomnography.

METHODS

We made a cross-sectional analysis of patients with obstructive sleep apnea undergoing DISE in search of positive airway pressure alternative treatment. Maxillary measurements were collected from a computed tomography scan (interpremolar distance, intermolar distance [IMD] and sella-nasion A point angle), findings from DISE, and sleep study variables from polysomnography. Correlation between computed tomography, DISE, and polysomnography data was assessed using Pearson's correlation, and receiver operating characteristic curves were determined for each facial measurement.

RESULTS

Sixty-nine patients were included in the study. The group with velopharyngeal circumferential collapse had mean IMD = 26.30 mm (25.5-31.45), and the group with anteroposterior collapse had mean IMD = 29.20 mm (26.8-33.10; P = .040). The group with complete tongue-base obstruction had mean interpremolar distance = 26.40 mm (25.1-28) and IMD = 26.30 mm (25.6-28.4), and the group without obstruction had mean interpremolar distance = 28.7 mm (27.2-30; P = .003) and IMD = 34.06 mm (32.1-37; P < .001). The receiver operating characteristic curve determined an IMD cutoff of 29.8 mm for predicting tongue-base obstruction.

CONCLUSIONS

The maxillary transverse deficiency, identified by reduction in interpremolar distance and IMD, predicted the occurrence of complete tongue-base obstruction, complete concentric collapse at the velopharynx, and multilevel obstruction during DISE. We did not find an association between the maxillary measurements and obstructive sleep apnea severity. These associations hold some promise in ultimately supplanting insights previously available only through DISE.

Effectiveness of Dental and Maxillary Transverse Changes in Tooth-Borne, Bone-Borne, and Hybrid Palatal Expansion through Cone-Beam Tomography: A Systematic Review of the Literature

Background and Objectives: Palatal expansion is a common orthodontic technique able to increase the transverse changes for subjects with constricted maxillary arches. The aim of the present investigation was to evaluate through a systematic review the tomography effectiveness of different palatal expander approaches. Materials and Methods: The database used to perform the screening and determine the eligibility of the clinical papers was PubMed (Medline). Results: The database search included a total of 284 results, while 271 articles were excluded. A total of 14 articles were included for the qualitative assessment. Conclusions: The effectiveness of the present studies reported that skeletal expansion was a useful approach to increase the transverse changes for subjects with constricted maxillary arches.

Reliability of 2 methods in maxillary transverse deficiency diagnosis

INTRODUCTION

The objective of this research was to evaluate the reliability of 2 methods (Andrews' Element III analysis and Yonsei transverse analysis) in maxillary transverse deficiency diagnosis.

METHODS

Plaster casts and cone-beam computed tomography images of 80 outpatients with skeletal Class I malocclusion (29 males and 51 females, mean age, 20.16 ± 8.22 years) were selected. Maxillary and mandibular width were measured, respectively, and independently by 2 examiners at an interval of 2 weeks, using Andrews' Element III analysis and Yonsei transverse analysis. Intraclass correlation coefficients and Bland-Altman plots of intraexaminer and interexaminer reliability were evaluated. After diagnosis, Cohen's kappa statistics were calculated to evaluate the diagnostic agreement.

RESULTS

The intraclass correlation coefficients were all above 0.85, indicating good to excellent reliability. Compared with Andrews' Element III analysis, Yonsei transverse analysis had higher intraexaminer and interexaminer reliability in both maxillary and mandibular width measurements. Thirty-one to 42 of the patients were diagnosed with maxillary transverse deficiency by 2 examiners using 2 methods. The intraexaminer and interexaminer Cohen's kappa values of Yonsei transverse analysis were all higher than those of Andrews' Element III analysis.

CONCLUSIONS

Both Andrews' Element III analysis and Yonsei transverse analysis had good to excellent reliability and substantial diagnostic agreement. Yonsei transverse analysis had higher reliability in maxillary and mandibular width measurements and higher diagnostic agreement, compared with Andrews' Element III analysis.

Two decades of research on CBCT imaging in DMFR - an appraisal of scientific evidence

OBJECTIVE

This article aims to appraise how scientific evidence related to CBCT has changed over the years, based on levels of evidence and diagnostic efficacy.

METHODS

A general search strategy was used in different databases (Pubmed, Embase, and Web of Science) to identify systematic reviews (SRs) on CBCT until November of 2020. The SRs included were divided according to different specialties of dentistry. A critical review of the articles was made, describing the level of evidence and efficacy.

RESULTS

In total, 75 articles were selected. There was an increase in the number of SRs on CBCT from 2014 onwards, as 83% of the SRs on this topic were published after 2013, and 72% between 2016 and to date. Twenty SRs (27%) performed meta-analysis. Only 28% of the SRs provided a detailed description of CBCT protocols. According to SR evidence, almost all specialties of dentistry have advanced concomitantly with the introduction of CBCT. The majority of SRs were related to clinical applications (level 2 of efficacy), followed by technical parameters (level 1 of efficacy). Only some CBCT models were mentioned in the SRs selected.

CONCLUSION

Over the course of 20 years, SRs related to CBCT applications for a broad range of dental specialties have been published, with the vast majority of studies at levels 1 and 2 of diagnostic efficacy. Not all CBCT models available on the market have been scientifically validated. At all times, one should remain cautious as such not to simply extrapolate in vitro results to the clinical setting. Also, considering the wide variety of CBCT devices and protocols, reported results should not be overstated or generalized, as outcomes often refer to specific CBCT devices and protocols.

Three-dimensional measurement and analysis of mandibular characteristics in subjects with impacted mandibular second molars

OBJECTIVE

To investigate the morphological characteristics of the mandible in subjects with impacted mandibular second molars by measuring and analysing the mandible in three dimensions.

SETTING AND SAMPLE POPULATION

In this retrospective study, the data of a total of 52 609 subjects who underwent cone-beam computed tomography (CBCT) for diagnosis and treatment were reviewed. According to the inclusion and exclusion criteria, 183 subjects with impacted mandibular second molars and 176 age- and sex-matched controls were included.

METHODS

A retrospective case-control study was designed. The 183 subjects were divided into two groups: group 1 (G1) comprised 120 patients with unilaterally impacted mandibular second molars, and group 2 (G2) comprised 63 patients with bilaterally impacted mandibular second molars. Group 3 (G3) contained 176 age- and sex-matched controls. The mandible was reconstructed with nineteen landmarks using Mimics software. Twelve linear lengths and 3 angles were measured.

RESULTS

The bilateral germination gap, mandibular body width and gonion width in G1 were significantly lower than those in G3 (P < .05), while the gnathion angle and first molar width values in G1 were significantly higher than those in G3 (P < .05). The results in G2 were similar to those in G1, but the differences between G2 and G3 were greater than those between G1 and G3. There were no significant differences in the other measurements among the groups.

CONCLUSION

The mandibles of the subjects with impacted second molars were constricted in terms of the sagittal length and transverse width.

[Three-dimensional analysis of the mandible with impacted mandibular second molar]

OBJECTIVE

To study the developmental and morphological characteristics of the mandible in patients with impacted mandibular second molar and to predict the possible trend of mandibular development via three-dimensional (3D) measurement and analysis.

METHODS

A total of 88 cases of impacted group and 88 cases of control group were screened out. 3D measurements were performed by using Mimics software. A total of 23 landmark points and 17 measurements were determined. The measurements were analyzed by t-test.

RESULTS

The mandible length, the space between the first molars, the space between mandibular angles, and the width between the first molars in the impacted group were lower than those in the control group (P<0.05). Moreover, the value of the submandibular angle was higher than that in the control group (P<0.05).

CONCLUSIONS

The impacted mandible of patients with mandibular second molar showed lack of sagittal and width development, and the impacted mandibular second molar was a manifestation of its degeneration.

Prediction of rapid palatal expansion success via fractal analysis in hand-wrist radiographs

INTRODUCTION

This study aimed to evaluate the efficacy of fractal analysis of hand-wrist radiography in the decision of conventional or surgery-assisted rapid palatal expansion (RPE).

METHODS

The study included 48 patients who underwent the RPE procedure. Study groups were as follows: group 1 (successful conventional RPE [n = 24, 5 male and 19 female patients; mean age ± standard deviation, 15.85 ± 0.97 years]) and group 2 (failed conventional RPE [n = 24, 5 male and 19 female patients; mean age ± standard deviation, 15.96 ± 1.08 years]). Fractal dimension (FD) analysis was conducted on hand-wrist radiographs of the patients for 4 different regions: the epiphysis-diaphysis line of the radius bone and the proximal, medial (MP3), and distal (DP3) phalanxes of the middle finger. A Student t test was performed to compare fractal values between the groups. A receiver operating characteristic analysis was applied to determine the optimal cutoff value of FDs. In addition, a Pearson correlation coefficient was calculated to evaluate the relationship between the fractal values and either age or hand-wrist stage in a second sample group (n = 90; age range, 8.7-18.7 years).

RESULTS

Fractal values of the radius, MP3, and DP3 were significantly increased in the failed conventional RPE group (P <0.05). The optimal cutoff value of the FD for predicting the success of conventional RPE was 1.16 in the radius, 1.18 in proximal phalanxes, 1.29 in MP3, and 1.08 in DP3. There was a positive correlation between fractal values of the radius and age or hand-wrist stages (P <0.05).

CONCLUSIONS

Within the limits of this study, results revealed that fractal analysis of hand-wrist radiographs might be considered a significant tool in the prediction of RPE success.

Dentofacial transverse development in Koreans according to skeletal maturation: A cross-sectional study

Objective

The aim of this study was to establish the normative data of dentofacial transverse dimensions according to the skeletal maturation stage in Korean adolescents with good occlusion, assess gender differences and determine correlations between transverse variables.

Methods

A total of 577 Korean subjects between ages 7 to 19 years and exhibiting skeletal Class I occlusion were categorized by skeletal maturation index (SMI) of Fishman using hand-wrist radiographs. Dentofacial transverse dimensions were assessed using posteroanterior cephalograms. Independent two-sample t-tests were used to analyze differences between genders. Pearson correlation coefficient was used to determine the correlation between transverse measurements.

Results

Dentofacial transverse norms relevant to skeletal maturation stages were established. The average maxillomandibular width difference and ratio at growth completion was 22.16 mm and 77.01% for males; 23.70 mm and 74.06% for females, respectively. Males had greater facial, maxillary and mandibular widths compared to females at every SMI stage. The maxillary and mandibular intermolar widths showed the strongest correlation for both sexes (r = 0.826 for males, r = 0.725 for females).

Conclusions

Dentofacial transverse norms of Korean adolescents were established according to developmental stage. All dentofacial widths were greater in males at growth completion. Maxillary and mandibular intermolar widths were strongly correlated. This study may serve as a guideline for the assessment of dentofacial transverse growth according to skeletal maturation stage in Korean adolescents with good occlusion.

ENPP1 and ESR1 genotypes associated with subclassifications of craniofacial asymmetry and severity of temporomandibular disorders

INTRODUCTION

We investigated whether ACTN3, ENPP1, ESR1, PITX1, and PITX2 genes which contribute to sagittal and vertical malocclusions also contribute to facial asymmetries and temporomandibular disorders (TMD) before and after orthodontic and orthognathic surgery treatment.

METHODS

One hundred seventy-four patients with a dentofacial deformity were diagnosed as symmetric or subdivided into 4 asymmetric groups according to posteroanterior cephalometric measurements. TMD examination diagnosis and jaw pain and function (JPF) questionnaires assessed the presence and severity of TMD.

RESULTS

Fifty-two percent of the patients were symmetric, and 48% were asymmetric. The asymmetry classification demonstrated significant cephalometric differences between the symmetric and asymmetric groups, and across the 4 asymmetric subtypes: group 1, mandibular body asymmetry; group 2, ramus asymmetry; group 3, atypical asymmetry; and group 4, C-shaped asymmetry. ENPP1 SNP-rs6569759 was associated with group 1 (P = 0.004), and rs858339 was associated with group 3 (P = 0.002). ESR1 SNP-rs164321 was associated with group 4 (P = 0.019). These results were confirmed by principal component analysis that showed 3 principal components explaining almost 80% of the variations in the studied groups. Principal components 1 and 2 were associated with ESR1 SNP-rs3020318 (P <0.05). Diagnoses of disc displacement with reduction, masticatory muscle myalgia, and arthralgia were highly prevalent in the asymmetry groups, and all had strong statistical associations with ENPP1 rs858339. The average JPF scores for asymmetric subjects before surgery (JPF, 7) were significantly higher than for symmetric subjects (JPF, 2). Patients in group 3 had the highest preoperative JPF scores, and groups 2 and 3 were most likely to be cured of TMD 1 year after treatment.

CONCLUSIONS

Posteroanterior cephalometrics can classify asymmetry into distinct groups and identify the probability of TMD and genotype associations. Orthodontic and orthognathic treatments of facial asymmetry are effective at eliminating TMD in most patients.