Changes in canine inclination after rapid and slow maxillary expansion compared to untreated controls

Early prevention of maxillary canine impaction: a randomized clinical trial

OBJECTIVES

To investigate the effect of three interceptive measures (slow maxillary expansion (SME) with removable plates (1), extraction of both upper deciduous canines (DC) (2) and no intervention (3)) on maxillary canine (MC) position in patients with early mixed dentition (EMD) and lack of upper arch space. These three groups were additionally compared to a control group (4) with adequate upper arch space.

NULL HYPOTHESIS

None of the studied strategies outperforms the others regarding improvement of MC position.

TRIAL DESIGN

Four-arm parallel group prospective randomized controlled trial.

PARTICIPANTS

Patients in EMD with at least one impacted MC, non-resorbed DC, and no crossbite.

INTERVENTIONS

Patients with a lack of space were randomly distributed to protocols (1), (2), and (3).

PRIMARY OBJECTIVE

To assess the change in MC position after 18 months follow up.

SECONDARY OBJECTIVES

To assess canine eruption and need for orthodontic intervention within 18-60 month follow up.

OUTCOME ASSESSMENT

Five variables defined canine position: sector, canine-to-midline angle, canine-to-first-premolar angle, canine-cusp-to-midline distance, and canine-cusp-to-occlusal-plane distance on two panoramic radiographs at 0 (T1) and 18 months (T2). Mean differences between groups were compared with linear mixed models, corrected for age and sex.

RANDOMIZATION

The patient allocation sequence was generated by an electronic randomization list.

BLINDING

The operator taking the measurements was blinded to the groups.

RESULTS

Seventy-six patients were included (142 canines, mean age 9.2 years, 60.5 per cent male, mean follow up 1.9 years), 19, 17, 14, and 26 patients in groups 1-4, respectively. In absence of dental crossbite in patients with lack of space and impacted MC, SME improved the canine sector (P = 0.040), compared to no intervention (P = 0.028). Canine-to-midline angle and canine-to-occlusal-plane distance significantly decreased in all groups at T2. Extraction improved the canine-to-first-premolar angle at T2 more than other strategies in EMD (P = 0.015-0.000).

CONCLUSIONS

Early SME improves the canine sector and reduces the need for major orthodontic intervention in the long term. Taking a first panoramic radiograph in EMD allows timely intervention in case of MC impaction.

TRIAL REGISTRATION NUMBER

NCT05629312 (Clinical Trials.org). Trial status: follow up ongoing.

What are the intra-arch risk factors for palatally displaced maxillary canine? - Results of a case-control study

INTRODUCTION

This study aimed to identify the intra-arch risk factors for palatally displaced canine by comparing the maxillary transverse dimensions, palatal depth (PD), and arch length (AL) of the subjects with and without impacted canine using cone-beam computed tomography (CBCT).

METHODS

In this prospective case-control study, 79 CBCT images of gender- and skeletal feature-matched subjects (25 cases and 54 controls) were compared. Based on the CBCT images, maxillary transverse widths at four levels (molar basal, molar alveolar, premolar basal, and premolar alveolar), maxillary PD, and maxillary AL were measured. Group comparisons were assessed using analysis of variance (ANOVA), followed by post-hoc Scheffe's test, and risk factors were identified using univariate and multivariate logistic regression.

RESULTS

The impacted canine group showed significantly smaller molar alveolar width, premolar alveolar width, PD, and greater AL compared to the control group (P = 0.046, P < 0.001, P = 0.003, and P = 0.001, respectively). No significant difference was observed in the molar and premolar basal width measurements between the two groups. Multivariate analysis showed that impacted maxillary canine was influenced by premolar alveolar width (odds ratio (OR): 0.669), PD (OR: 0.532), and AL (OR: 1.739).

CONCLUSION

Intra-arch risk factors, such as reduced maxillary premolar transverse alveolar width, PD, and greater AL, are associated with palatally displaced canine.

CBCT Analysis of Dento-Skeletal Changes after Rapid versus Slow Maxillary Expansion on Deciduous Teeth: A Randomized Clinical Trial

The aim of the present study was to compare skeletal and dental changes after rapid maxillary expansion (RME) and slow maxillary expansion (SME) performed by a Leaf Expander (LE) with upper deciduous teeth as anchorage and using 3D CBCT (Cone Beam Computed Tomography) analysis. Mixed dentition patients were randomly divided in two groups, according to the different expansion used anchored on maxillary primary second molars: the RME group (n = 16) was treated with a Hyrax type expander, whereas the SME group (n = 16) was treated with an LE expander. CBCT scans were performed before (T1) and after treatment (T2) and analyzed with a custom landmarks system. A paired t-test was used for intragroup analysis between T1 and T2, and a Student t-test was used for intergroup analysis; statistical significance was set at 0.05. Both RME and SME groups showed a statistically significant increase in dental and skeletal diameters. Group comparisons between T1 and T2 showed a significant expansion rate in the RME group for upper permanent molars (p = 0.025) but not for deciduous molars (p = 0.790). Moreover, RME showed higher increases for skeletal expansion evaluated at nasal walls (p = 0.041), whereas at pterygoid plates did not show any significant differences compared with the SME group (p = 0.849). A significant transverse expansion could be achieved with the expander anchored on deciduous teeth. RME and SME produced effective both skeletal and dentoalveolar transverse expansion; RME produced more anterior expansion than SME but less control regarding the permanent molar decompensation. SME by LE therefore could be an efficient and helpful alternative in the treatment of transverse maxillary deficiency in growing patients.

Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for surgical exposure, in children aged 9 to 14 years

BACKGROUND

A permanent upper (maxillary) canine tooth that grows into the roof of the mouth and frequently does not appear (erupt) is called a palatally displaced canine (PDC). The reported prevalence of PDC in the population varies between 1% and 3%. Management of the unerupted PDC can be lengthy, involving surgery to uncover the tooth and prolonged orthodontic (brace) treatment to straighten it; therefore, various procedures have been suggested to encourage a PDC to erupt without the need for surgical intervention.

OBJECTIVES

To assess the efficacy, safety and cost-effectiveness of any interceptive procedure to promote the eruption of a PDC compared to no treatment or other interceptive procedures in young people aged 9 to 14 years old.

SEARCH METHODS

An information specialist searched four bibliographic databases up to 3 February 2021 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

We included randomised controlled trials (RCT) involving at least 80% of children aged between 9 and 14 years, who were diagnosed with an upper PDC and undergoing an intervention to enable the successful eruption of the unerupted PDC, which was compared with an untreated control group or another intervention.

DATA COLLECTION AND ANALYSIS

Two review authors, independently and in duplicate, examined titles, keywords, abstracts, full articles, extracted data and assessed risk of bias using the Cochrane Risk of Bias 1 tool (RoB1). The primary outcome was summarised with risk ratios (RR) and 95% confidence intervals (CI). We reported an intention-to-treat (ITT) analysis when data were available and a modified intention-to-treat (mITT) analysis if not. We also undertook several sensitivity analyses. We used summary of findings tables to present the main findings and our assessment of the certainty of the evidence.

MAIN RESULTS

We included four studies, involving 199 randomised participants (164 analysed), 108 girls and 91 boys, 82 of whom were diagnosed with unilateral PDC and 117 with bilateral PDC. The participants were aged between 8 and 13 years at recruitment. The certainty of the evidence was very low and future research may change our conclusions. One study (randomised 67 participants, 89 teeth) found that extracting the primary canine may increase the proportion of PDCs that successfully erupt into the mouth at 12 months compared with no extraction (RR 2.87, 95% CI 0.90 to 9.23; 45 participants, 45 PDCs analysed; very low-certainty evidence), but the CI included the possibility of no difference; therefore the evidence was uncertain. There was no evidence that extraction of the primary canine reduced the number of young people with a PDC referred for surgery at 12 months (RR 0.61 (95% CI 0.29 to 1.28). Three studies (randomised 132 participants, 227 teeth) found no difference in the proportion of successfully erupted PDCs at 18 months with a double primary tooth extraction compared with extraction of a single primary canine (RR 0.68, 95% CI 0.35 to 1.31; 119 participants analysed, 203 PDCs; mITT; very low-certainty evidence). Two of these studies found no difference in the proportions referred for surgical exposure between the single and the double primary extraction groups data at 48 months (RR 0.31, 95% CI 0.06 to 1.45).  There are some descriptive data suggesting that the more severe the displacement of the PDC towards the midline, the lower the proportion of successfully erupted PDCs with or without intervention.

AUTHORS' CONCLUSIONS

The evidence that extraction of the primary canine in a young person aged between 9 and 14 years diagnosed with a PDC may increase the proportion of erupted PDCs, without surgical intervention, is very uncertain. There is no evidence that double extraction of primary teeth increases the proportion of erupted PDC compared with a single primary tooth extraction at 18 months or the proportion referred for surgery by 48 months. Because we have only low to very low certainty in these findings, future research is necessary to help us know for sure the best way to deal with upper permanent teeth that are not erupting as expected.

Orthodontic treatment for posterior crossbites

BACKGROUND

A posterior crossbite occurs when the top back teeth bite inside the bottom back teeth. The prevalence of posterior crossbite is around 4% and 17% of children and adolescents in Europe and America, respectively. Several treatments have been recommended to correct this problem, which is related to such dental issues as tooth attrition, abnormal development of the jaws, joint problems, and imbalanced facial appearance. Treatments involve expanding the upper jaw with an orthodontic appliance, which can be fixed (e.g. quad-helix) or removable (e.g. expansion plate). This is the third update of a Cochrane review first published in 2001.

OBJECTIVES

To assess the effects of different orthodontic treatments for posterior crossbites.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched four bibliographic databases up to 8 April 2021 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of orthodontic treatment for posterior crossbites in children and adults.

DATA COLLECTION AND ANALYSIS

Two review authors, independently and in duplicate, screened the results of the electronic searches, extracted data, and assessed the risk of bias of the included studies. A third review author participated to resolve disagreements. We used risk ratios (RR) and 95% confidence intervals (CIs) to summarise dichotomous data (event), unless there were zero values in trial arms, in which case we used odds ratios (ORs). We used mean differences (MD) with 95% CIs to summarise continuous data. We performed meta-analyses using fixed-effect models. We used the GRADE approach to assess the certainty of the evidence for the main outcomes.

MAIN RESULTS

We included 31 studies that randomised approximately 1410 participants. Eight studies were at low risk of bias, 15 were at high risk of bias, and eight were unclear. Intervention versus observation For children (age 7 to 11 years), quad-helix was beneficial for posterior crossbite correction compared to observation (OR 50.59, 95% CI 26.77 to 95.60; 3 studies, 149 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 4.71 mm, 95% CI 4.31 to 5.10; 3 studies, 146 participants; moderate-certainty evidence). For children, expansion plates were also beneficial for posterior crossbite correction compared to observation (OR 25.26, 95% CI 13.08 to 48.77; 3 studies, 148 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 3.30 mm, 95% CI 2.88 to 3.73; 3 studies, 145 participants, 3 studies; moderate-certainty evidence). In addition, expansion plates resulted in higher inter-canine distances (MD 2.59 mm, 95% CI 2.18 to 3.01; 3 studies, 145 participants; moderate-certainty evidence). The use of Hyrax is probably effective for correcting posterior crossbite compared to observation (OR 48.02, 95% CI 21.58 to 106.87; 93 participants, 3 studies; moderate-certainty evidence). Two of the studies focused on adolescents (age 12 to 16 years) and found that Hyrax increased the inter-molar distance compared with observation (MD 5.80, 95% CI 5.15 to 6.45; 2 studies, 72 participants; moderate-certainty evidence). Intervention A versus intervention B When comparing quad-helix with expansion plates in children, quad-helix was more effective for posterior crossbite correction (RR 1.29, 95% CI 1.13 to 1.46; 3 studies, 151 participants; moderate-certainty evidence), final inter-molar distance (MD 1.48 mm, 95% CI 0.91 mm to 2.04 mm; 3 studies, 151 participants; high-certainty evidence), inter-canine distance (0.59 mm higher (95% CI 0.09 mm  to 1.08 mm; 3 studies, 151 participants; low-certainty evidence) and length of treatment (MD -3.15 months, 95% CI -4.04 to -2.25; 3 studies, 148 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and Haas for posterior crossbite correction (RR 1.05, 95% CI 0.94 to 1.18; 3 studies, 83 participants; moderate-certainty evidence) or inter-molar distance (MD -0.15 mm, 95% CI -0.86 mm to 0.56 mm; 2 studies of adolescents, 46 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and tooth-bone-borne expansion for crossbite correction (RR 1.02, 95% CI 0.92 to 1.12; I² = 0%; 3 studies, 120 participants; low-certainty evidence) or inter-molar distance (MD -0.66 mm, 95% CI -1.36 mm to 0.04 mm; I² = 0%; 2 studies, 65 participants; low-certainty evidence).  There was no evidence of a difference between Hyrax with bone-borne expansion for posterior crossbite correction (RR 1.00, 95% CI 0.94 to 1.07; I² = 0%; 2 studies of adolescents, 81 participants; low-certainty evidence) or inter-molar distance (MD -0.14 mm, 95% CI -0.85 mm to 0.57 mm; I² = 0%; 2 studies, 81 participants; low-certainty evidence).  AUTHORS' CONCLUSIONS: For children in the early mixed dentition stage (age 7 to 11 years old), quad-helix and expansion plates are more beneficial than no treatment for correcting posterior crossbites. Expansion plates also increase the inter-canine distance. Quad-helix is more effective than expansion plates for correcting posterior crossbite and increasing inter-molar distance. Treatment duration is shorter with quad-helix than expansion plates. For adolescents in permanent dentition (age 12 to 16 years old), Hyrax and Haas are similar for posterior crossbite correction and increasing the inter-molar distance. The remaining evidence was insufficient to draw any robust conclusions for the efficacy of posterior crossbite correction.

Condylar Changes in Children with Posterior Crossbite after Maxillary Expansion: Tridimensional Evaluation

(1) Background: To investigate condylar position in subjects with functional posterior crossbite comparing findings before and after rapid maxillary expansion (RME) treatment through 3D analysis; (2) Methods: Thirty-two Caucasian patients (14 males, mean age 8 y 8 m ± 1 y 2 m; 18 females mean age 8 y 2 m ± 1 y 4 m) with functional posterior crossbite (FPXB) diagnosis underwent rapid palatal expansion with a Haas appliance banded on second deciduous upper molars. Patients’ underwent CBCT scans before rapid palatal expansion (T0) and after 12 months (T1). The images were processed through 3D slicer software; (3) Results: The condylar position changes between T1 and T0 among the crossbite and non-crossbite sides were not statistically significant, except for the transversal axis. At T1, the condyles moved forward (y axis) and laterally (x axis), they also moved downward (z axis) but not significantly; (4) Conclusions: Condilar position in growing patients with functional posterior crossbite did not change significantly after rapid maxillary expansion.

Occlusal Plane and Skeletal Changes After Cervical Headgear Treatment With and Without Lower Utility Arch in Class II Growing Patients

The purpose of this study was to investigate skeletal and dental changes affecting occlusal plane inclination after cervical headgear treatment with and without lower utility arch. In order to distinguish the orthodontic changes from natural growth a control group was employed.The sample of this study consisted by 20 Class II subjects (10 males, 10 females; mean age 8.54) treated by using cervical headgear, 19 class II children (19 males, 9 females; mean age 8.64) treated with cervical headgear and utility arch, and 21 Class II patients (11 males, 10 females; mean age 8.41) who had no therapy.Lateral head films were studied for all the patients before treatment (T1) and after therapy (T2) for all the treated groups and at the beginning and at the end of observational period for the control group; cephalometric analysis was carried out in order to seek for the modifications between time points and between groups.Means and standard deviation have been analyzed for all the groups. In order to compare the modification between the time points within the same group the ANOVA test was applied. The ANOVA test was used to compare the mean differences (T2-T1) of 3 groups.The study revealed that there were significant changes in occlusal plane inclination after the different treatment modalities employed instead control group. The treatment with cervical headgear and utility arch is more effective than cervical headgear alone in lowering occlusal plane posteriorly when it is compared with controls.