Apical root resorption due to mandibular first molar mesialization: A split-mouth study

Alveolar bone loss and root resorption in mesialized second molars in mandibular first molar extraction cases as compared to contralateral non-extraction side in young adults: A retrospective cross-sectional study

INTRODUCTION

The alveolar bone loss (ABL) and external apical root resorption (EARR) depict the safety of mesialization of mandibular second molars into the extraction space of mandibular first molars. The aim of this study was to evaluate the ABL and EARR after closure of mandibular first molar extraction space by mesialization of second molar on extraction side (ES) as compared to the contralateral non-extraction side (NES).

MATERIAL AND METHODS

A retrospective cross-sectional study was carried out using the pre and posttreatment orthodontic records of young adults with complete set of permanent dentitions treated with extraction of unilateral mandibular first molar and non-extraction treatment on the contralateral side. All patients underwent mini-implant supported mesialization of second molar on ES. The ABL and EARR of second molar on ES and contralateral NES were measured on digital orthopantomograms. The ABL and EARR of second molars on ES and contralateral NES were compared using independent sample t-test.

RESULTS

A total of 36 subjects (14 males and 22 females) were included in the study. The mean treatment duration for molar mesialization was 28.75±8.05months. The mean crown and root movements of mandibular second molar on ES were 10.94±1.25mm and 9.04mm±1.14mm, as compared to 0.91±1.01mm and 0.77±0.83mm on contralateral NES, respectively. The mean ABL and EARR at mandibular second molar were found to be significantly greater on the ES than the contralateral NES (P<0.001 and<0.05, respectively). A total of seven patients (19.4%) experienced ABL≥1mm on ES as compared to none in the contralateral NES. EARR of>2mm of at least one root was found in seven patients (19.4%) in ES as compared to four (11%) in contralateral NES.

CONCLUSION

There was small but statistically significant difference in the ABL and EARR of mesialized mandibular second molar at first molar ES as compared to the contralateral NES. For majority of patients this difference was small but few isolated cases experienced severe ABL and EARR.

Effect of piezoincision on the rate of mandibular molar mesialization: A randomised clinical trial

Background and Aim

The aim of this clinic study was to investigate the effect of piezoincision on the rate of mandibular molar mesialization using clinical, radiological, and biochemical methods.

Materials and Methods

Twenty-one patients requiring mandibular first molar extraction and second molar mesialization were included in the study which was designed as split-mouth study. Piezoincision was performed on the buccal surface of alveolar bone following regional alignment to the randomly selected side. 150 g of force was applied to the second molar teeth using mini-screw-supported anchorage after the piezoincision. Cone beam computed tomography (CBCT), gingival crevicular fluid (GCF) and digital model records of the patients were obtained. Two- and three-dimensional measurements were performed and compared on the CBCT images in a study which lasted 24 weeks.

Results

According to the model analysis, the canine-second molar distance was consistently reduced and a greater decrease was measured on the experimental group (p < 0.05). Second molar mesial rotations increased in both groups (p < 0.001). Two-dimensional measurements on CBCT images showed increased mesial and buccal tipping of second molars in experimental group (p < 0.001). There was a significant increase in mesialization measurements of experimental group (p < 0.001). Three-dimensional measurements on the CBCT images showed a decrease of root length in both groups (p < 0.001), and a greater decrease was found in the experimental group (p < 0.001). When intra-group changes in GCF results were examined, it was observed that there was no significant change in osteoprotegerin (OPG) values over time in experimental group (p = 0.148).

Conclusion

The piezoincision technique provided acceleration of mandibular molar mesialization and did not cause further damage to the buccal alveolar bone. Piezoincision can be used as a safe method in the mandibular molar region.

Evaluation of external apical root resorption caused by fixed functional treatment of class II malocclusion : Cast splint Herbst appliance vs. Forsus fatigue resistant device

INTRODUCTION

The aim of this study was to evaluate and compare the effects of class II fixed functional treatment with a cast splint Herbst appliance (HA; Herbst Set I, Dentaurum, Ispringen, Germany) and Forsus fatigue resistant device (FRD; 3M Unitek Corp., Monrovia, CA, USA) on external apical root resorption (EARR) in posterior teeth.

METHODS

In all, 40 patients (15 male and 25 female) with class II division 1 malocclusion were treated with two fixed functional appliances: HA (20 patients, mean age 14.60 ± 1.14 years) and FRD (20 patients, mean age 14.15 ± 1.28 years). The vestibular lengths of the first molars and premolars were measured on panoramic radiographs and converted to actual tooth length using the magnification coefficient (MC), which was calculated using dental models. Intragroup comparisons of pre- and posttreatment tooth lengths were performed with the paired t‑test and Wilcoxon signed-rank test, while intergroup comparisons were performed with the Mann-Whitney U test.

RESULTS

Pretreatment tooth length values decreased significantly with HA and FRD therapies for all posterior teeth. The maximum resorption was observed in the mandibular first premolar with a mean of 0.81 mm following HA and 1.55 mm following FRD treatment. While no significant difference existed between the EARR values of the HA and FRD groups for maxillary teeth, the amount of EARR of mandibular posterior teeth in the FRD group was significantly higher than in the HA group.

CONCLUSIONS

In patients treated with HA or FRD, the tooth length of posterior teeth decreased to a clinically minor but statistically significant degree. The root resorption effect of FRD therapy in mandibular posterior teeth was significantly higher than that of HA therapy.

Association of Craniofacial Patterns with the Curve of Spee and the Time Required for Orthodontic Levelling

The curve of Spee (CoS) is an important parameter for an individualized treatment plan. The available information regarding a potential association of the depth of the curve of Spee with various skeletal craniofacial characteristics is conflicting and it is also unknown whether certain craniofacial parameters affect the duration of the levelling phase of orthodontic treatment. A prospective sample of 32 patients with mild to moderate crowding that underwent orthodontic treatment with full fixed appliances was used to study these topics. The craniofacial characteristics were captured on pre-treatment lateral cephalometric radiographs and measurements of the CoS were performed on the initial 3D digital dental models using the Viewbox 4 software. Non-parametric statistics and Spearman’s correlations were applied. Weak negative correlations were detected between the CoS depth and the SNA and SNB angles. There was no other association between the CoS and craniofacial parameters, including various anteroposterior measurements. Furthermore, there was no significant association of any craniofacial parameter with the duration of the levelling. Contrary to certain clinical beliefs, it can be argued that the craniofacial characteristics are not associated with the CoS and the time required for its levelling in subjects with moderate pre-treatment CoS depth.

The effects of a corticotomy on space closure by molar protraction using TSADs in patients with missing mandibular first molars

INTRODUCTION

The purpose of this study was to evaluate the effects of a triangular-shaped corticotomy on the protraction of second and third molars in patients with missing mandibular first molars.

SUBJECTS AND METHODS

The corticotomy and non-corticotomy groups consisted of sixteen first molars in fifteen patients (28.6 ± 9.4 years) and nineteen first molars in fifteen patients (26.6 ± 8.4 years), respectively. A triangular-shaped corticotomy was performed between the second premolar and molar. Temporary skeletal anchorage devices (TSADs) were placed between the first and second premolars in both groups. Mandibular dentition variables were measured on the pre and post-treatment panoramic radiographs and lateral cephalograms. Analysis of covariance was performed.

RESULTS

The corticotomy group exhibited 2.8 mm more inter-radicular correction between the second molar to second premolar roots (P < .001) and 1.6 mm more inter-radicular distance correction between the third molar to second premolar roots compared to the non-corticotomy group (P < .01). The corticotomy group required 5.5 months less treatment time for space closure (P < .05), but the total treatment time was the same for both groups.

CONCLUSIONS

The inter-radicular distance between the mandibular second premolar and molar and treatment times for space closure was significantly reduced in the corticotomy group.

Effect of the timing of second molar bonding on the duration of the mandibular arch levelling: a randomized clinical trial

INTRODUCTION

This study investigated the effect of the timing of second molar bonding on the time required for the levelling of the mandibular dental arch.

TRIAL DESIGN

Single-centre two-arm parallel randomized clinical trial using random permuted blocks. Allocation concealment was achieved through sealed envelopes. There was blinding in outcome assessment, but not of patient or operator.

METHODS

Thirty-six patients (12-18 years old) with mild to moderate crowding and fully erupted mandibular second molars were assigned randomly (1:1 ratio) in two groups. Group A started fixed orthodontic treatment by bracket bonding in both jaws. Initial wire was 0.014" NiTi. Lower second molar tubes were bonded at the time of 0.016" x 0.022" NiTi wire placement. Group B was same as Group A, but second lower molars were bonded at the first appointment. Placement of the 0.017" x 0.025" stainless steel wire in the mandibular arch was considered the primary endpoint of the trial, indicating the completion of the levelling phase. The days required from bonding to the endpoint comprised the main outcome. Non-parametric statistics were applied.

RESULTS

There were two dropouts in each group. The compared groups had similar baseline characteristics regarding age, sex, overjet, overbite, space in the dental arch, average Curve of Spee (CoS), and maximum CoS. Group A tended to require more days for levelling (median: 203 days) than Group B (median: 168 days). However, this difference was not statistically significant (P = 0.128). From the tested occlusal factors, only initial overjet was found to be moderately associated with the days required to complete levelling of the mandibular arch (r = 0.45, P = 0.009).

CONCLUSIONS

In the frame of the current study, the duration of the levelling phase of orthodontic treatment with fixed appliances was not affected by the timing of second molar inclusion in the appliance. Future research could aim in cases with deep CoS to generalize the present findings and in larger sample sizes.

Factors associated with alveolar bone depth mesial to the mandibular third molars after orthodontic protraction

INTRODUCTION

The objective of this research was to study the factors associated with the alveolar bone depth mesial to the mandibular third molars (M8) after the mandibular second (M7) and third molars were protracted into the space of the mandibular first molars (M6), which were newly extracted for orthodontic treatment or extracted more than 1 year before treatment.

METHODS

This retrospective study included 57 adult patients (mean age 23.40 ± 4.40 years) in whom M6 were newly extracted for orthodontic treatment or extracted more than 1 year before treatment. The alveolar bone depth mesial to M8 was measured on posttreatment panoramic radiographs. The vertical, horizontal, and angular changes of M8 were measured on both pre- and posttreatment panoramic radiographs. Linear correlation and regression analyses were conducted to explore the factors associated with the alveolar bone depth mesial to M8.

RESULTS

The alveolar bone conditions of M6 (R= -0.391, P <0.001) and the vertical movement directions of M8 (R= -0.433, P <0.001) were significant factors associated with the alveolar bone depth mesial to M8 after orthodontic protraction.

CONCLUSIONS

Without considering the pretreatment periodontal status of M8, patients with M6 extracted exceeding 1 year before treatment and with M8 extruded after orthodontic protraction may exhibit deeper alveolar bone depth mesial to M8.

Effect of mandibular first molar mesialization on alveolar bone height: a split mouth study

Objectives

To evaluate the risk of vertical alveolar bone loss (ABL) in mesialized mandibular permanent molars due to space closure in patients with unilateral second premolar agenesis. The contralateral side served as control.

Subjects and methods

Twenty-five retrospectively selected subjects (median age 14.9, range 12.0, 31.9 years) were analyzed. Space closure (approximately 10 mm) was performed using skeletal anchorage. ABL was measured at mesial and distal sites of first molars in pre- and post-treatment panoramic radiographs. Measurements were corrected for distortion and magnification of radiographs. Molar angulation according to the occlusal plane was also evaluated. Permutational multivariate analysis of covariance (MANCOVA), followed by pairwise comparisons, was performed.

Results

MANCOVA resulted in no difference in ABL between the distal sites of mesialized molars and the control sites. On the contrary, there was statistically higher ABL, at the mesial sites of mesialized versus non-mesialized molars (p = 0.042; median 0.19 mm; range − 0.82, 1.33); though the difference was not clinically relevant. In the space closure side, mesially, only two patients had ABL higher that 1 mm. No patient had a severe bone level height defect (> 3 mm distance from the cementoenamel junction) at any point.

When testing differences in molar angulation between sites and from pre- to post-treatment condition, no significant difference was detected (p > 0.05, median − 1.9°, range − 13.5, 6.2).

Limitations

This is a retrospective study on panoramic radiographs.

Conclusions

Space closure through extensive tooth movement was identified as a risk factor for vertical ABL, at the mesial sites of mandibular first molars. However, the amount of ABL was not clinically relevant, and thus this treatment option is considered safe in terms of ABL.