Effect of maxillary anteroposterior position on profile esthetics in headgear-treated patients

Three-dimensional digital imaging analysis of the palatal bone thickness for orthodontic mini-implant insertion - determination of the safe zone and angulation

BACKGROUND

In order to successfully perform orthodontic mini-implant procedures successfully for the subsequent anchoring of orthodontic appliances, it is crucial to know the palatal bone thickness. This is usually assessed using two-dimensional radiographs. The purpose of this study was to use a three-dimensional digital imaging measurement method to provide information on palatal bone volume and bone thickness and to make recommendations on the optimal and safe insertion site and angle for palatal mini-implants.

METHODS

For this observational, cross-section study, pre-existing cone beam computed tomography scans of 184 patients were converted into 3D Standard Tessellation Language (STL) models of the maxilla. The area between the canine and the first molar was divided into 6 regions of interest (ROIs), three on the left side of the palate and three on the right side. The bone thickness of the palate was analyzed volumetrically and linearly while simulating different mini-implant insertion angles of 0°, 10°, 20° and 30° degrees relative to the palatal surface.

RESULTS

Among the ROIs, the greatest mean bone thickness was observed in the region of the first premolars with a mean distance (MD) of 10.44 ± 2.53 mm and decreased from anterior to posterior (MD: 3.44 ± 1.16 mm). The highest volume (Vol) values were also measured in the anterior palatal region (Vol: 1127.26 ± 483.91 mm3), while there was also a decrease in the posterior region (Vol: 394.36 ± 180.22 mm3). Regarding the simulated palatal mini-implant insertion sites, the greatest bone thickness was found in the anterior region, at the level of the canines with an angle of 0° (MD: 12.25 ± 3.75 mm). In the more posterior region, at the level between the first and second premolars, the greatest bone thickness was observed at an angle of 30° (MD: 7.93 ± 3.81 mm). Gender differences were found.

CONCLUSION

This clinical study showed that the paramedian region at the level of the first premolar is the safest site for orthodontic mini-implant placement as evaluated by three-dimensional measurements. The results showed that implant insertion angle, gender and age are important aspects to consider when planning and inserting orthodontic palatal mini-implants.

TRIAL REGISTRATION

N.a.

Anterior En Masse Retraction in Orthodontics

This article reviews and critically analyzes the literature on mini-implants (temporary anchorage devices) for anterior en masse retraction in orthodontics. The search methods used were an E-database search, a secondary computerized search of orthodontics journals, and a reference list of selected studies. Eligibility criteria included individuals who underwent orthodontic treatment for correction of malocclusion with premolar extraction. Data were taken from PubMed and Scopus as well as the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews. Keywords used for searching the article were temporary anchorage devices, premolar extraction, orthodontics, and anterior en masse retraction, Anterior en masse retraction with sliding mechanics in pre-adjusted edgewise appliances was considered for the study. Data collection and analysis involved three different researchers performing three steps of selection. All titles were initially filtered for irrelevant review articles. In the first step, all summaries from the selected studies were reviewed, and in the second, the entire content of the papers was read. The study was then discarded based on qualifying standards. A chart was created using the data from the final chosen research as well as the findings. The following information was evaluated for the final table: author, publication year, research structure, study group, sample size, methods/measures, study findings, and conclusion about frictionless mechanics. Results showed that a meta-analysis was not feasible due to clinical and statistical variability, as well as variations in study design, sample selection, and sample size. Thus, it was concluded that sliding mechanisms are widely employed in orthodontic treatment, but temporary anchorage devices and sliding mechanisms deliver great results. There is a need to raise awareness about these devices and use them with care.

Orthodontic maximum anchorages in malocclusion treatment: A systematic review and network meta-analysis

OBJECTIVE

We did a network meta-analysis and systematic review among patients seeking for maximum anchorage and provided a guidance of selecting certain systems in clinical practice.

METHODS

Seven databases were searched, and randomized controlled trials (RCTs) published with no language restrictions from January 1994 to February 2021 comparing any of the following seven anchorage systems for maximum anchorage orthodontic treatment were selected(PROSPERO: CRD42019117995). A network meta-analysis (NMA) was then conducted to integrate direct evidence with indirect evidence based on logical inference to compare and rank treatments for maximum anchorages in the capacity of maintaining anchorage and duration of total treatment time.

RESULTS

Nine publications with 522 participants were considered eligible and were taken into evaluation. According to the capacity of anchorage reinforcement, three skeleton anchorages including miniscrew implants, midpalate implants and Onplant midpalate implants were significantly more effective than conventional anchorages including headgears, TPAs and Nance buttons respectively. According to conventional anchorages, headgears and Nance buttons were significantly more effective than TPA. The strategy ranking reflected the same results as above. However, miniscrew implants required the longest total treatment time.

CONCLUSIONS

In general, miniscrew impants are most effective in reserving anchorage. Nance buttons require the least total treatment time. Total evidence is graded as moderate. Midpalatal implants might be the best choice when doing treatment planning because it has the most favorable balance between effectiveness and treatment time. But data analysis of the acceptability and acquisition cost of those anchorage systems must be done to make final decisions.

Comparison of Anchorage Efficiency of Orthodontic Mini-implant and Conventional Anchorage Reinforcement in Patients Requiring Maximum Orthodontic Anchorage: A Systematic Review and Meta-analysis

OBJECTIVE

To compare the clinical effectiveness of mini-implants (MIs) and conventional anchorage appliances used for orthodontic anchorage reinforcement in patients with class I or II malocclusion with bimaxillary protrusion.

MATERIALS AND METHODS

Literature search was conducted through PubMed, Embase, and Cochrane from inception to July 2018. The following Medical Subject Heading terms were used for the search string: "skeletal anchorage", "temporary anchorage devices", "miniscrew implant", "mini-implant", "micro-implant". Standardized mean difference (SMD) and 95% confidence interval (CI) of horizontal and vertical movements of teeth from baseline were used for comparison.

RESULTS

A total of 12 studies were included in the final analysis. MI group significantly lowered mesial movement of molars compared to conventional anchorage group (SMD = -1.48, 95% CI = -2.25 to -0.72; P = .0002). There was significantly higher retraction of incisors in the MI group than in the conventional group (SMD = -0.47 mm, 95% CI = -0.87 to -0.07; P = .02). No significant difference was seen in vertical movement of molars (SMD = -0.21 mm, 95% CI = -0.87 to 0.45; P = .52) and incisors (SMD = -0.30, 95% CI = -1.18 to 0.58; P = .5).

CONCLUSION

MIs seem to be more effective than the conventional anchorage devices in terms of minimizing unintended mesial movement of molars with maximum retraction of anterior teeth.

Glabellar vertical line as a reference goal for anteroposterior maxillary position

Objective:

The aim of this study was to evaluate the use of glabellar vertical line (GVL) as the anteroposterior maxillary position goal.

Methods:

A cross-sectional study was conducted assessing 129 participants (20.21 ± 1.99 years): 67 women (20.16 ± 1.99 years), and 62 males (20.26 ± 2.06 years). The facial profile photographs were taken with a posed smile in natural head position. The linear distance from the most facial convexity of the upper central incisor (FA) to the goal anterior-limit line (GALL) and also from FA to GVL were measured and compared. Wilcoxon signed-ranks test was applied. To determine the correlation between the distances, Spearman’s correlation coefficient was used. Simple and multiple linear regression were also performed.

Results:

The GALL-GVL separation was 0.54 ± 1.14 mm (95%CI: 0.34-0.74). A strong correlation between FA-GALL and FA-GVL distances (Spearman’s rho=0.983 [95%CI: 0.976-0.988], p< 0.01) was identified. The FA-GVL distance explains almost all the total variation of FA-GALL (R²=95.84%, p< 0.01). The FA-GALL distance can be predicted by using the formula: FA-GALL=0.5+0.9*(FA-GVL).

Conclusion:

These findings suggest that GVL could be used as an easier-to-use treatment goal to determine the maxillary anteroposterior position, compared to GALL, to improve facial harmony profile goals in cases where the maxillary incisors are properly positioned anteroposteriorly.

Association between normative and perceived esthetic results after treatment of mandibular retrognathism

Abstract Introduction This cross-sectional study aimed to associate the normative cephalometric results of mandibular retrognathism treatment with patient perception on the esthetic improvement of facial profile. Objective this cross-sectional study aimed to associate the normative cephalometric results of mandibular retrognathism treatment with patient perception on the esthetic improvement of facial profile. Material and method The normative cephalometric results were obtained from lateral cephalometric radiographs of a sample of 24 Class II malocclusion patients in the pubertal growth spurt. Such patients were treated with a mandibular advancement device and evaluated by comparing pre- and post-treatment variables. The same radiographs were used to produce standardized black silhouettes that were randomly arranged. Patients were instructed to choose their preferred profile and indicate the changes perceived using a 7-point Likert scale. The data were compared with cephalometric results using a mixed-model methodology for time-repeated measures, Student’s t-test, and t-test for heterogeneous variances, at 5% significance level. Result A rate of 75% of patients preferred post-treatment silhouettes and changes were perceived regardless of the choice of either pre- or post-treatment profile. There was no significant difference between the cephalometric variables of the tracings that produced the silhouettes considered better or worse after the evaluation. Conclusion There was no association between the cephalometric results after treatment and the perception of esthetic improvement by patients treated for mandibular retrognathia.

Changes in apical base sagittal relationship in Class II malocclusion treatment with and without premolar extractions: A systematic review and meta-analysis

OBJECTIVE

To evaluate the changes in apical base sagittal relationship in Class II treatment with and without premolar extractions.

MATERIALS AND METHODS

Controlled studies evaluating ANB angle changes after Class II Division 1 malocclusion treatment with or without premolar extractions were considered. Electronic databases (PubMed, Embase, Web of Science, Scopus, The Cochrane Library, Lilacs, and Google Scholar) without limitations regarding publication year or language were searched. Risk of bias was assessed with Risk Of Bias in Non-randomized Studies-of Interventions tool of the Cochrane Collaboration. Mean difference (MD) and 95% confidence interval (CI) were calculated from the random-effects meta-analysis. Subgroup and sensitivity analyses were also performed.

RESULTS

Twenty-five studies satisfied the inclusion criteria and were included in the qualitative synthesis. Eleven nonextraction and only one extraction Class II treatment studies presented untreated Class II control group. Therefore, meta-analysis was performed only for the nonextraction protocol. In treated Class II nonextraction patients, the average of the various effects was a reduction in the ANB angle of 1.56° (95% CI: 1.03, 2.09, P < .001) compared with untreated Class II subjects. Class II malocclusions treated with two maxillary-premolar extractions and four-premolar extractions produced estimated mean reductions in ANB of -1.88° and -2.55°, respectively. However, there is a lack of low-risk-of-bias studies.

CONCLUSIONS

According to the existing low quality evidence, the apical base sagittal relationship in nonextraction, two-maxillary and four-premolar extractions Class II treatments decreases -1.56°, 1.88° and 2.55°, respectively. Further studies are necessary to obtain more robust information.

Skeletal and dental effects of molar distalization using a modified palatal anchorage plate in adolescents

OBJECTIVE

To evaluate and compare skeletal effects and the amount of molar distalization in maxilla using modified palatal anchorage plate (MPAP) vs headgear appliances in adolescent patients.

MATERIALS AND METHODS

Pre- and posttreatment lateral cephalograms of 45 Class II malocclusion patients were analyzed; 24 were treated with MPAP appliances (age, 12.4 years) and 21 with headgear (age, 12.1 years). Fixed orthodontic treatment started with the distalization process in both groups. Thirty-two variables were measured and compared between both groups using multivariate analysis of covariates.

RESULTS

There was no significant main effect of the appliance type on the treatment results (P  =  .063). Also, there was no significant main effect of the appliance type on both pre- and posttreatment comparisons (P  =  .0198 and .135, respectively). The MPAP and headgear groups showed significant distalization of maxillary first molars (3.06 ± 0.54 mm and 1.8 ± 0.58 mm, respectively; P < .001). Sagittal skeletal maxillomandibular differences were improved after treatment (P < .001), with no significant differences between the two groups. No significant difference in treatment duration was found between the groups.

CONCLUSIONS

The MPAP showed a significant skeletal effect on the maxilla. Both MPAP and headgear resulted in distalization of maxillary first molars. Therefore, it is recommended that clinicians consider the application of MPAP, especially in noncompliant Class II patients.

Effects on the maxilla and cranial base caused by cervical headgear: a longitudinal study

Objectives: The aim of this study is to test the possible orthopedic effects of cervical headgear on the cranial base and maxilla. Study design: a sample consisting of 79 subjects with skeletal class II malocclusion was divided into two groups. The experimental group was made up of 41 patients all treated with cervical headgear. The control group included a total of 38 non-treated patients. Each one of these groups was then subdivided according to age into one of three groups: prepubescent, pubescent or post-pubescent. Cephalometric parameters were compared in both groups in order to measure the cranial base angle and the vertical and sagittal position of the maxilla. Additionally, cephalometric superimpositions taken at the beginning and end of the study were compared. Results: results revealed significant differences in the cranial base angle and in the SNA angle (p<0.05). However, no differences were observed in the variables that measure the maxillomandibular relationship. While no changes were noted in the palatal plane slope, a flattening of the cranial base was found caused by the cervical headgear, in addition to a retrusion of point A that does not mean there was a reduction in the maxillomandibular relationship. Conclusions: cervical headgear treatment induces cephalometric flattening of the cranial base and a decrease of the SNA angle.

Key words:Orthodontics, cervical headgear, class II treatment, cephalometry, superimposition.