Is orthodontic treatment without premolar extractions always non-extraction treatment?

Mandibular second molar extraction: A retrospective cohort study of spontaneous occlusal changes in adolescent patients

OBJECTIVES

Evaluate long-term spontaneous occlusal changes following L7 extraction in adolescent patients.

MATERIALS AND METHODS

Study models of 144 participants (63 males, 81 females) retrospectively assessed prior to L7 extraction (9-16 years old; T1) and following L8 eruption (14-25 years old; T2). All received upper fixed appliances. A sub-group (n = 86) received no lower fixed appliances and acted as controls. Occlusal changes were compared between treatment (lower fixed appliance) and control (no lower fixed appliance) groups using PAR index. At T2, L8 occlusal outcome was assessed using ABO grading system.

RESULTS

Mean follow-up period 6 (SD 2) years. At T1, lower scores observed in control group for Lower Anterior (P < .001), Midline (P = .033) and Lateral Segments (P = .040) components. At T2, lower scores continued being observed in control group for Midline (P < .001) and Lateral segment (P = .019) components. Higher decrease in Lower Anterior PAR scores observed in treatment group (<.001) with comparable scores between groups at T2 (P = .057). Similar PAR score changes between groups for Lateral Segments, Overjet and Overbite components. At T2, no significant difference observed in Total PAR score reduction between control (83%) and treatment (82%) groups. Good-to-acceptable occlusal outcome of the L8 observed in 81.55% of cases at T2 with no difference between groups.

CONCLUSION

In growing patients with mild mandibular crowding, extraction of L7 followed by upper fixed appliance therapy, leads to favourable occlusal changes over a 6-year follow-up period, with or without lower fixed appliance therapy, being an alternative extraction protocol where lower fixed appliance therapy is not recommended.

Relationship between the amount of mesial movement of the mandibular first molar and angular changes of the mandibular third molar: A retrospective comparative study in growing patients with and without first premolar extraction

OBJECTIVES

The main objective of this study was to assess the relationship of the amount of mesial movement of mandibular first molar (MFM) and angular changes of the mandibular third molar (MTM) in orthodontic patients. The secondary objective of this study was to compare the obtained values in extraction and non-extraction orthodontic patients.

MATERIAL AND METHODS

In this cross-sectional retrospective study were enrolled all the eligible patients (12-16 years) with and without first premolar extraction that met the inclusion criteria. The angle between the longitudinal axis of MTM and horizontal reference plane (HRP) (to calculate the angular change of MTM), and the distance between the cementoenamel junction of the mesial surface of MFM and the bisector of the anterior nasal spine and nasal septum (to determine the amount of mesial movement of MFM) were measured on pre- and post-treatment panoramic radiographs. The correlation between the two variables was analysed and compared between extraction and non-extraction patients using STATA v. 14.2 software.

RESULTS

A total of 100 fixed orthodontic patients with and without first premolar extraction (n=50) whose treatment had been accomplished were included in the study. In the non-extraction group, the mean amount of mesial movement of MFM was 1.45mm and the mean angular change of MTM was 4.28 degrees; this correlation was significant (P<0.05). These values were 2.98mm and 7.17 degrees in the first premolar extraction group, respectively, with a significant correlation (P<0.05). However, the difference in this respect was not significant between the two groups (P>0.05). According to the regression model, 1mm mesial movement of MFM would averagely cause 2.2-degree angular change in MTM, adjusting for the effect of extraction/non-extraction treatment plan.

CONCLUSION

The mesial movement of MFM was significantly correlated with the angular changes of MTM in extraction and non-extraction orthodontic patients, with no significant difference between them.

Changes in third molar position after Class II subdivision malocclusion treatment with asymmetric extractions

INTRODUCTION

This study aimed to assess the changes in third molars angulation and their available space after Class II subdivision malocclusion treatment with asymmetric premolar extractions.

METHODS

The sample consisted of 37 patients (17 male, 20 female and mean age 13.18 ± 1.99 years) in group 1 (Type 1 Class II subdivision) and 25 (10 male, 15 female, mean age 13.56 ± 2.46 years) in group 2 (Type 2 Class II subdivision). In group 1, extractions were performed in the two maxillary quadrants and in the Class I mandibular quadrant. In group 2, extraction was performed in the Class II maxillary quadrant. Panoramic radiographs were used to evaluate third molar angulations and their available space pre- and post-treatment. Radiographic measurements were performed with Dolphin^® Imaging 11.9. Paired t tests were used for intragroup comparison between stages and sides.

RESULTS

In Type 1, there were similar improvements in third molar angulations and increases in the space available on the extraction quadrants in the maxillary arch. In the mandibular arch, there was significantly greater improvement in angulation and greater space availability in the extraction quadrant after treatment. In Type 2, there was significantly greater improvement in angulation and available space for the maxillary third molar on the extraction quadrant. In the mandibular arch, there was a similar improvement in the available space for the third molars.

CONCLUSIONS

After treatment, both groups presented better angulation and significantly greater space for third molar eruptions on the extraction quadrants, when compared to the homologous non-extraction quadrants.

Effects of Angle class II correction with the Forsus fatigue resistant device on mandibular third molars : A retrospective study

PURPOSE

The goal was to evaluate the effects of Angle class II malocclusion treatment using the Forsus fatigue resistant device (FRD, 3M, St. Paul, MN, USA) on the position and angulation of mandibular third molars and retromolar space.

PATIENTS AND METHODS

In all, 58 class II patients (mean age 13.6 ± 1.8 years) treated with the FRD (FRD group) were compared with 51 class I patients (mean age 13.5 ± 1.6 years) who underwent orthodontic treatment (control group). A total of 109 mandibular third molars in the FRD group and 91 in the control group were evaluated. Changes in the retromolar space, angulation of the second (ɣ) and third molars (β), and the angle between these teeth (α) were assessed with panoramic radiographs taken at the beginning and the end of the treatment. Data were statistically analyzed.

RESULTS

At the end of the treatment, there were significant increases in ɣ and β in the FRD group and ɣ in the control group (p < 0.05). The decrease in α in the FRD group and increase in the control group were not significant (p > 0.05); however, this change led to a small significant change between the groups (p < 0.05). The retromolar space significantly increased in the FRD group compared to the control group (p < 0.05). No significant correlation was found between retromolar space and third molar uprighting in any of the groups (p > 0.05).

CONCLUSION

Class II correction with FRD led to mesialization of the lower arch which provided an increase in the retromolar space. Little improvement in the uprighting of the third molars occurred.

Relationship between the Position of Impacted Third Molars and External Root Resorption of Adjacent Second Molars: A Retrospective CBCT Study

BACKGROUND AND OBJECTIVES

Impacted third molars (ITM) are the most commonly-impacted teeth. There is a risk for ITM to cause a number of pathological conditions, and external root resorption (ERR) of adjacent teeth is one of the most prevalent. Retaining or prophylactic extraction of ITM is a polemic topic. External root resorption of adjacent teeth is one of possible indications for prophylactic removal of ITM. The aim of this study was to assess the relationship between external root resorption (ERR) on the distal aspect of second molars' roots and positional parameters of ITM. Methods: Cone beam computed tomography scans of 109 patients (41 males, 68 females; mean age 26.4 ± 7.9 years) with 254 ITM (131 in the maxilla and 123 in the mandible) were retrospectively analyzed. Positional parameters of ITM (mesio-distal position, angulation, impaction depth, and available eruption space) were evaluated. The presence, location, and depth of ERR of adjacent second molars were assessed. Results: Analysis showed a relationship between ITM impaction depth, mesial inclination angle, and the presence of ERR. Mesial inclination angle of more than 13.6° increased the odds of ERR occurrence by 5.439 (95% CI, 2.97-9.98). ITM presence at the level of ½ of roots of the adjacent second molar or more apically increased the odds of ERR occurrence by 2.218 (95% CI, 1.215-4.048). No significant correlation was detected between the occurrence of ERR and patient age, gender, or the available eruption space in the mandible. Depth of ERR did not depend on its location. Conclusions: Incidence of ERR in second molars is significantly associated with mesial inclination and a deep position of ITM.

The effect of first and second premolar extractions on third molars: A retrospective longitudinal study

OBJECTIVES

To analyse the effect of first and second premolar extractions on eruption space for upper and lower third molars and on third molar position and angulation during orthodontic treatment.

METHODS

The sample consisted of 296 patients of which 218 patients were orthodontically treated without extraction and 78 patients with extraction of first or second premolars. The eruption space for third molars was measured on pre- and posttreatment lateral cephalograms, whereas the angulation, vertical position, the relation with the mandibular canal and the mineralization status of third molars were evaluated using pre- and posttreatment panoramic radiographs. All data were statistically analyzed.

RESULTS

The increase in eruption space and the change in vertical position of upper and lower third molars significantly differed between patients treated with and without premolar extractions, whereas the change in angulation, relationship with the mandibular canal and mineralization status of the third molars did not significantly differ between patients treated with and without premolar extractions.

CONCLUSIONS

The retromolar space and the position of third molars significantly change during orthodontic treatment in growing patients. Premolar extractions have a positive influence on the eruption space and vertical position of third molars, whereas they do not influence the angular changes of third molars. Due to the retrospective character of the study, these conclusions should be carefully considered. Further prospective research is necessary for better insights into this complex topic.

CLINICAL SIGNIFICANCE

This study stresses the importance of considering the possible effects of orthodontic treatment on third molars during treatment planning.

[Possibilities and limits of orthodontico-surgical treatments in case of macrodontia]

INTRODUCTION

Tooth-arch discrepancy is a disproportion between dental volume and bone base. Extraction therapy can be a solution in case of excessive tooth volume and insufficient basal bone length. Techniques including bone distraction popularized by Ilizarov in the fifties allow the increase of the basal arch length in the maxilla as well as in the mandible.

MATERIALS AND METHODS

We will describe the procedure of this dental arch length augmentation since the reflection about the therapeutic plan until the sufficient arch length is obtained and describe the indications of this orthodontic and surgical treatment in case of dental crowding, buccal and labial inclination and functional problems.

DISCUSSION

Distraction is an interesting technique to be considered for the management of macrodontia that allows to get enough basal bone lenght to reach the therapeutic goal.

Can extraction sites affect the profile?

Tooth extractions, apart from the third molars, which it seems is normal to extract today, have always given rise to controversy among orthodontists with both supporters and opponents. It is legitimate to raise the question regarding the need for extractions in our treatment plan and to opt for the first or second premolars as the extraction site, or even the first molars when the latter are decayed and the germs of the third molars are in place. Facial esthetic guides us in our treatment decisions but we must free ourselves from the so-called esthetic lines drawn up many years ago and, for the most part, on the basis of lateral headfilms and small study samples. Particular ethnic features are another major factor to be borne in mind, given that the vast majority of cephalometric standards were based on Caucasian populations. In this article, we will draw on clinical studies to illustrate the thinking behind the need for extractions and the choice of extraction sites.