Identifying cortical plate inclination as a parameter to re-assess transverse discrepancies in untreated adults with different vertical facial heights-A retrospective CBCT study

OBJECTIVE

To determine the inclination angles of buccal, palatal cortical plates and assess its harmony with existing molar buccolingual inclination in adults with different vertical facial heights. The aim of this study was to identify the role of cortical plate inclination as a diagnostic tool for determining alveolar support in adults with transverse discrepancies.

MATERIALS AND METHODS

One-hundred and fifty seven CBCTs (50-Hypo-divergent, 51-Normo-divergent and 56-Hyper-divergent growth patterns) of untreated adults were utilized. Cross-sectional slices with respect to the maxillary first molar were taken as orientation landmarks in defined reference planes. Inclination angles for the first molar, buccal and palatal cortical plate were determined with respect to the palatal plane. ANOVA and Post Hoc Tukey's HSD test were carried out to determine significant differences between groups.

RESULTS

Molar inclination was significantly greater in hyper-divergent groups compared to normo-divergent and hypo-divergent groups (P < .05). Greater variation between molar inclination and cortical plate inclination (buccal and palatal) was seen in hyper-divergent groups (P < .05). Hypo-divergent and normo-divergent groups showed almost similar molar and cortical plate inclinations; however, there was a significant difference between the buccal and palatal cortical plates (P < .05).

CONCLUSIONS

Cortical plate inclination is in agreement with molar inclination in hypo- and normo-divergent groups when compared to hyper-divergent groups. In adults with decreased/normal facial heights, greater balance and harmony is observed between the dental and alveolar substructures in the posterior region. In adults with increased facial heights, a greater amount of dentoalveolar compensation is seen with respect to the molar and its surrounding bone support.

Comparison of Skeletal and Dental Changes Obtained from a Tooth-Borne Maxillary Expansion Appliance Compared to the Damon System Assessed through a Digital Volumetric Imaging: A Randomized Clinical Trial

The purpose of this study was to evaluate and compare dental and skeletal changes associated with the Damon and Rapid Maxillary Expander (RME) expansion using Cone-Beam Computed Tomography (CBCT). Eighty-two patients, from The University of Alberta Orthodontic Clinic, were randomly allocated to either Group A or B. Patients in Group A received orthodontic treatment using the Damon brackets. Patients in Group B received treatment using the Hyrax (a type of RME) appliance. CBCT images were taken two times (baseline and after expansion). The AVIZO software was used to locate 18 landmarks (dental and skeletal) on sagittal, axial, and coronal slices of CBCT images. Comparison between two groups showed that transverse movement of maxillary first molars and premolars was much greater in the Hyrax group. The lateral movements of posterior teeth were associated with buccal tipping of crowns. No clinically significant difference in the vertical or anteroposterior direction between the two groups was noted. Alveolar bone next to root apex of maxillary first premolar and molar teeth showed clinically significant lateral movement in the Hyrax group only. The comparison between two groups showed significantly greater transverse expansion of the first molar and first premolars with buccal tipping in the RME group.

Dental and skeletal changes associated with the Damon system philosophical approach

OBJECTIVE

To compare the skeletal and dentoalveolar changes produced by the Damon system's treatment philosophy to traditional orthodontic treatment techniques.

MATERIALS AND METHODS

An electronic search in four major databases was completed: Cochrane, PubMed, EMBASE, and Google Beta Scholar on October 5th, 2018. Randomized controlled trials, prospective and retrospective controlled clinical trials were included in this systematic review. The quality assessment of individual studies was done using two different tools: The Cochrane Risk of Bias Assessment Tool (RTCs) and The Methodological Index for Non-Randomized Studies (MINORS) (non-RCTs).

RESULTS

Seven studies were included for this qualitative analysis. Six studies compared the Damon system to various types of conventional (non self-ligating bracket) system as a comparison group. One study used a quad helix as a comparison for a few months before a full bonding appointment with conventional brackets. The majority of studies found an increase in maxillary inter-canine, inter-premolar, and intermolar distance after the treatment in both the Damon and comparison groups. Yet, all studies concluded that there is no significant difference in the final transverse dimension between the two groups. One study also found that the transverse expansion was achieved mainly by tipping movement of posterior dentition, and a decrease in the posterior buccal bone area was evident in both groups after treatment.

CONCLUSION

There is not enough evidence to support the claim that the Damon system allows additional arch expansion with better tipping control than with traditional techniques.

Potential risks of orthodontic therapy: a critical review and conceptual framework

This review examines some of the potential risks of orthodontic therapy along with their evidence base. The risks of orthodontic treatment include periodontal damage, pain, root resorption, tooth devitalization, temporomandibular disorder, caries, speech problems and enamel damage. These risks can be understood to arise from a synergy between treatment and patient factors. In general terms, treatment factors that can influence risk include appliance type, force vectors and duration of treatment whilst relevant patient factors are both biological and behavioural. Hence, the natural variation between orthodontic treatment plans and patients gives rise to variations in risk. A good understanding of these risks is required for clinicians to obtain informed consent before starting treatment as well as to reduce the potential for harm during treatment. After considering each of these risks, a conceptual framework is presented to help clinicians better understand how orthodontic risks arise and may therefore be mitigated.

Extractions, retention and stability: the search for orthodontic truth

Background and objectives

From the beginnings of modern orthodontics, questions have been raised about the extraction of healthy permanent teeth in order to correct malocclusions. A hundred years ago, orthodontic tooth extraction was debated with almost religious intensity by experts on either side of the issue. Sheldon Friel and his mentor Edward H. Angle both had much to say about this controversy. Today, after significant progress in orthodontic practice, similar arguments are being voiced between nonextraction expansionists and those who see the need for tooth extractions in some orthodontic patients. Furthermore, varying concepts of mechanical retention of treatment results have evolved over the years which have been misinterpreted as enhancing natural orthodontic stability.

Materials and methods

In this essay, representing the Ernest Sheldon Friel Memorial Lecture presented in 2016 at the 92nd Congress of the European Orthodontic Society, a full spectrum of evidence from biology, anthropology and history is critically discussed in the search for truth among highly contested orthodontic variables: extraction versus nonextraction, fixed retention versus limited retention, and rationalized stability versus biological homeostasis.

Conclusions and implications

Conscientious clinicians should try to develop individualized treatment plans for their patients, and not be influenced by treatment 'philosophies' with untested claims in clinical orthodontics.

Short-term effects of systematic premolar extraction on lip profile, vertical dimension and cephalometric parameters in borderline patients for extraction therapy--a retrospective cohort study

OBJECTIVES

The belief of many orthodontists that premolar extraction therapy leads to a loss of vertical dimension and an aggravated facial profile often predetermines a non-extraction approach. We investigated the short-term effects of systematic premolar extraction in borderline cases for extraction therapy on dentofacial parameters, especially vertical dimension and facial profile.

MATERIALS AND METHODS

Of 50 juvenile borderline cases for extraction treatment with a distinct sagittal overjet of 6-9 mm and dental crowding of >6 mm, 25 had all first premolars extracted, whereas the 25 control patients received non-extraction orthodontic treatment with corresponding fixed and removable appliances. Patient selection by multivariate cluster analysis ensured homogeneity at baseline regarding dentoskeletal parameters. Parameter changes were determined with radiographic cephalograms and compared between the extraction and non-extraction group.

RESULTS

The systematic extraction of premolars in borderline patients with a distinct sagittal overjet and crowding did not significantly influence sagittal or vertical skeletal dimension, while leading to a slightly more concave lip profile due to incisor retraction compared to the non-extraction control group.

CONCLUSIONS

The influence of premolar extractions on facial profile is often overestimated, since only slight changes in lip profile are to be expected. In integrated treatment planning, the extraction decision should not be primarily based on concerns about the aggravation of facial profile and loss of vertical dimension.

CLINICIAL RELEVANCE

The decision, whether to extract healthy premolars in borderline patients for extraction therapy, is difficult to make. Our study clarifies the repercussions on cephalometric dentofacial parameters, facilitating future orthodontic extraction decisions.

A prospective randomized split-mouth study on pain experience during chairside archwire manipulation in self-ligating and conventional brackets

OBJECTIVE

To investigate patient discomfort during archwire engagement and disengagement in patients treated with self-ligating and conventional brackets using a split-mouth design.

MATERIALS AND METHODS

Eighteen consecutive patients (15 female, 3 male; age: 22.2 ± 6.4 years) who requested treatment with fixed orthodontic appliances were randomly assigned for bonding with SmartClip self-ligating brackets on one side of the dentition and conventional standard edgewise brackets on the other. During the course of treatment, patients rated the discomfort experienced during every archwire engagement and disengagement using a numeric rating scale. Results were evaluated for round and rectangular nickel titanium and rectangular stainless steel, titanium molybdenum, and Elgiloy archwires. Patients also rated their overall experience retrospectively for both bracket systems.

RESULTS

Regardless of archwire type, disengagement was rated as being significantly more painful on the SmartClip side (P  =  .027). For rigid, rectangular archwires, engagement and disengagement were rated as being significantly more painful on the SmartClip side (P  =  .031; P  =  .004). Retrospective ratings favored conventional brackets beyond ratings recorded during treatment.

CONCLUSION

Engagement and disengagement of rigid rectangular archwires caused more pain with SmartClip self-ligating brackets than with conventional ones. Careful archwire manipulation and patience during full alignment are essential for limiting chairside pain. Low pain levels will help ensure treatment satisfaction and compliance.