An evaluation of root resorption incident to orthodontic intrusion

External root resorption after orthodontic treatment: a study of contributing factors

Purpose

The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption.

Materials and Methods

This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment.

Results

Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption.

Conclusion

These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth.

External apical root resorption in patients treated by serial extractions followed by mechanotherapy

INTRODUCTION

In the course of orthodontic treatment with serial extractions (SE), spontaneous unraveling of crowded incisors occurs. It was hypothesized that SE followed by mechanotherapy will cause less external apical root resorption (EARR) than orthodontic treatment with late extractions (LE).

METHODS

The records of 24 patients who underwent SE and mechanotherapy and 24 control patients who underwent LE and mechanotherapy were examined. The groups were matched for sex, central incisor root development and morphology, malocclusion class, ANB angle, and overjet. Lateral cephalograms taken before mechanotherapy (T1) and after mechanotherapy (T2) were traced and superimposed on the palatal plane with registration on the osseous details superior to the maxillary incisors and on the palatal curve. The T1 and T2 central incisor lengths, changes in the axial inclination, and horizontal and vertical apical movements were measured.

RESULTS

The tooth lengths in both groups were reduced: the EARR values were 1.8 mm (± 1.1) in the SE group and 2.1 mm (± 1.4) in the LE group, and the difference between the groups was not significant. The movements of the teeth in both groups were similar in absolute values.

CONCLUSIONS

The spontaneous unraveling of incisor crowding with SE treatment does not prevent the common EARR seen in patients treated with LE, when the patients are treated by mechanotherapy after the SE.

Effects of intrusion combined with anterior retraction on apical root resorption

This study evaluated the influence of intrusion mechanics combined with anterior retraction on root resorption of the maxillary incisors. A sample of 56 patients was divided into two groups: group 1 comprised 28 patients (12 females and 16 males), presenting with an increased overjet and deep overbite (6.48 and 4.78 mm, respectively) treated with reverse curve of Spee intrusion mechanics and group 2 comprised 28 patients (12 females and 16 males) with an increased overjet of 5.67 mm and a normal overbite of 1.12 mm. The initial mean ages for groups 1 and 2 were 13.41 and 13.27 years, respectively. Pre- (T1) and post- (T2) treatment periapical radiographs were used to evaluate root resorption. The groups were compared using the Mann-Whitney U-test. Correlation between root resorption and tooth movement was investigated with Spearman's correlation coefficient. The subjects in group 1 had statistically greater root resorption (P < 0.05) than those in group 2. The initial overbite severity and the amount of correction had significant positive correlations with root resorption (r = 0.324 and r = 0.320, respectively). The combination of anterior retraction with intrusive mechanics causes more root resorption than anterior retraction of the maxillary incisors alone.

Severe root resorption in orthodontic patients treated with the edgewise method: prevalence and predictive factors

INTRODUCTION

Our aims in this study were to assess the prevalence of severe root resorption and identify possible associations in orthodontic patients treated with the edgewise method.

METHODS

The sample included 1049 patients who had periapical radiographs taken for all incisors before and after treatment. The radiographs were examined by 2 orthodontists using an x-ray viewer with standard light intensity. These variables were collected: root shape, overbite, initial resorption, and hypodontia. The patients were classified according to sex, Angle classification, ethnicity, age, duration of treatment, type of dentition (mixed or permanent), and treatment with or without extraction of 4 premolars. Resorption was considered severe when it affected more than a third of the length of the root. Statistical analysis included the chi-square test and both simple and multiple logistic regression (P < or =0.05).

RESULTS

Severe root resorption was observed in 14.5% of the sample. Patients treated with exodontia of the first premolars (odds ratio [95% CI] = 6.38 [4.2-9.7]), those who had triangle-shaped roots at the beginning of treatment (odds ratio [95% CI] = 4.67 [3.1-6.9]), and those with initial root resorption (odds ratio [95% CI] = 4.52 [2.7-7.6]) had a greater chance of developing severe root resorption during orthodontic treatment.

CONCLUSIONS

A high prevalence of severe root resorption was observed in Brazilian patients treated with the edgewise method. The main factors directly involved in severe resorption were extraction of first premolars, triangle-shaped roots, and root resorption before treatment.

Forces and moments on posterior teeth generated by incisor intrusion biomechanics

OBJECTIVES

To comparatively evaluate the extrusive forces and torquing moments on the posterior dentition generated during anterior intrusion with different intrusion techniques in the maxillary and mandibular dental arch.

MATERIAL AND METHODS

Seven wire specimens were used for each of the following intrusive arches: Utility arch 0.016 x 0.016' Blue Elgiloy, Utility arch 0.017 x 0.025' TMA and Burstone Intrusion arch 0.017 x 0.025' TMA. The wires were inserted on bracketed dental arches constructed on maxillary Frasaco models, segmented mesially to the maxillary canines. Simulated intrusion from 0.0-3.0 mm was performed on the Orthodontic Measurement and Simulation System (OMSS). The forces and moments were recorded in all three planes of space at 0.1 mm increments and the values at 3.0 mm for all wires were used for all statistical evaluations. The data were analyzed, separately for the forces and moments, by means of two-way analysis of variance (ANOVA) with forces and moments serving as the dependent variables and intrusion technique and jaw (maxilla or mandible) as the independent variable. Post hoc multiple comparisons were performed using the Tukey test at .05 error rate.

RESULTS

The 0.016 x 0.016' Blue Elgiloy utility arch exerted the highest posterior extrusive forces, 15% higher than the 0.017 x 0.025' TMA utility and 40% higher in comparison with the 0.017 x 0.025' TMA Burstone intrusion arch.The lowest posterior moment in the sagittal plane was generated by the 0.017 x 0.025' TMA Burstone intrusion arch. The 0.016 x 0.016' Blue Elgiloy utility arch exerted 15% higher posterior moments and the 0.017 x 0.025' TMA utility 25% higher. Forces and moments were consistently larger for the mandible compared to the maxilla for the same intrusion technique.

CONCLUSIONS

The upper Burstone 0.017 x 0.025' TMA intrusion arch exerted the lowest forces/moments on posterior teeth. The highest forces were generated by the 0.016 x 0.016-inch Blue Elgiloy utility arch and the highest moments by the lower 0.017 x 0.025-inch TMA utility arch.

Forces and moments generated with various incisor intrusion systems on maxillary and mandibular anterior teeth

OBJECTIVE

To evaluate the comparative intrusive forces and torquing moments in the sagittal plane generated during anterior intrusion using different incisor intrusion mechanics in the maxillary and mandibular anterior teeth.

MATERIALS AND METHODS

Five wire specimens were used for each of the following intrusive arches: non-heat-treated, 0.016 x 0.016-inch blue Elgiloy utility arch, 0.017 x 0.025-inch TMA utility arch, and 0.017 x 0.025-inch TMA Burstone intrusion arch. The wires were constructed according to the specifications given by their inventors and were inserted on bracketed dental arches on Frasaco models, segmented mesial to the canines. Simulated intrusion from 0.0-1.5 mm was performed on the Orthodontic Measurement and Simulation System (OMSS), and forces and moments were recorded at 0.1 mm vertical displacement increments. All measurements were repeated five times for each specimen, and maximum values recorded at 1.5 mm for all wires were used for all statistical evaluations. The data were analyzed with two-way analysis of variance (ANOVA) with forces and moments serving as the dependent variables, separately, and wire type and jaw as the independent variables. Post hoc multiple comparisons were performed using the Tukey test (.05 error rate).

RESULTS

The 0.017 x 0.025-inch TMA Burstone intrusion arch exerted the lowest intrusive forces, followed by the 0.017 x 0.025-inch TMA utility and the 0.016 x 0.016-inch blue Elgiloy utility arch. The lowest anterior moment in the sagittal plane in this experiment was generated from the 0.017 x 0.025-inch TMA Burstone intrusion arch.

CONCLUSIONS

The intrusive forces, as well as the generated moments, were always higher in the mandible, where significant differences were observed among the configurations tested.

Intramaxillary and intermaxillary absolute anchorage with an endosseous dental implant and rare-earth magnets

This case report describes the management of a partially edentulous adult with a severe deepbite malocclusion and a collapsed buccal segment because of supraeruption of the maxillary second and third molars. The treatment involved placement of an endosseous dental implant to achieve absolute intermaxillary and intramaxillary anchorage. Rare-earth magnets embedded in acrylic bite-blocks were used to intrude the supraerupted maxillary molars on the right side. After use as an anchorage device, the implant was restored and brought into occlusion. Good occlusal and esthetic results were achieved with this cost-effective treatment.

Mini-implants for en masse intrusion of maxillary anterior teeth in a severe Class II division 2 malocclusion

This case report describes the treatment of a 16-year-old post pubertal male patient with a severe Class II division 2 malocclusion and 100% deep bite. In the first phase of treatment, a 'Jones-Jig' molar distalization appliance was used to distalize the maxillary molars by more than 6 mm, to achieve a Class I molar relation. In the second phase of treatment, mini-implants were inserted between the roots of the maxillary lateral incisor and canine to intrude all the maxillary anterior teeth en masse in a single step. Four millimetres of intrusion was achieved. The implants remained stable throughout treatment. In the mandibular arch the incisors were proclined to alleviate the severe crowding. Good overjet and overbite was achieved and has been maintained one year after completion of active orthodontic treatment.

Evaluation of root resorption after open bite treatment with and without extractions

INTRODUCTION

In this study, we evaluated the root resorption degree in open bite and normal overbite patients, treated with and without premolar extractions.

METHODS

A sample of 120 patients was selected and divided into 4 groups. Group 1 comprised 32 patients treated with premolar extractions with an initial mean age of 14.01 +/- 2.58 years and an initial mean overbite of -3.45 +/- 0.23 mm. Group 2 included 28 open bite patients treated without extractions, with an initial mean age of 13.27 +/- 2.75 years and an initial mean overbite of -3.10 +/- 0.24 mm. Group 3 comprised 30 patients with normal overbite, treated with premolar extractions, having a mean age of 13.28 +/- 1.79 years and a mean overbite of 1.09 +/- 0.24 mm at the beginning of treatment. Group 4 consisted of 30 patients with normal overbite, treated without extractions, at a mean age of 12.87 +/- 1.43 years and a mean overbite of 1.67 +/- 0.24 mm at the beginning of treatment. The groups were matched by initial age, treatment time, and malocclusion type. Pretreatment and posttreatment periapical radiographs were used to evaluate the amount of root resorption. The groups were compared by using the Kruskal-Wallis and Dunn nonparametric tests. Correlations between the degree of root resorption and amount of tooth movement, usage time of anterior vertical elastics, and treatment time were investigated with the Spearman correlation coefficient.

RESULTS

No statistically significant difference was found between the root resorption degrees of open bite vs normal overbite groups, but the extraction groups had statistically significant greater root resorption than the nonextraction groups. Significant correlations were observed in the extraction groups between root resorption degree and amount of overjet correction and retraction of maxillary incisor apex.

CONCLUSIONS

Root resorption was similar between open bite and normal overbite treatment protocols, but extraction treatment showed greater root resorption than nonextraction treatment. There was a statistically significant correlation of overjet correction and retraction of maxillary central incisor apices with the degree of root resorption.

Anterior open bite with temporomandibular disorder treated with titanium screw anchorage: Evaluation of morphological and functional improvement

Skeletal anterior open bite is one of the most challenging malocclusions to correct because it is difficult to establish absolute anchorage for molar intrusion with traditional orthodontic mechanics. In addition, patients with anterior open bite sometimes have signs and symptoms of temporomandibular disorders (TMD). In this article, we report the successful treatment of a patient with severe skeletal anterior open bite and TMD; we used titanium screw anchorage. The patient, a woman, age 19 years 11 months, had an open bite of -4.0 mm and increased anterior lower facial height. The titanium screws were implanted in the mandible, and intrusion force was provided with elastic chains for 6 months. After active treatment for 36 months, her mandibular first molars were intruded about 3.0 mm, and good occlusion was achieved. Her retrognathic chin and convex profile were improved both by upward rotation of the mandible and advancement genioplasty with vertical reduction. After treatment, the TMD signs and symptoms were reduced, and improvements of both function and occlusion were achieved. Molar intrusion with titanium screw anchorage might be a useful treatment option to improve function, occlusion, and facial esthetics in patients with severe anterior open bite and TMD.

Physical properties of root cementum: Part 9. Effect of systemic fluoride intake on root resorption in rats

INTRODUCTION

Orthodontically induced inflammatory root resorption is a common complication in orthodontic treatment. Fluoride has been reported to have a beneficial effect against root resorption in dental traumatology. The effect of fluoride on orthodontically induced inflammatory root resorption has not been investigated. This study was undertaken to investigate the effect of fluoride on the incidence of root resorption.

METHODS

Thirty-two female 8-week-old Wistar rats were separated into 4 groups. Two groups (6 rats per group) were controls; they did not undergo orthodontic tooth movement. The other 2 groups (10 rats per group) had orthodontic tooth movement consisting of activated 100-g closing nickel-titanium coils (NiTi 10-000-06, GAC International, Bohemia, NY) connecting the mandibular first molar to the incisors. Fluoridated water (100 ppm) was given ad libitum to 1 control and 1 experimental group. The other 2 groups received deionized water. After 2 weeks, the animals were killed, and the samples were harvested. Resorption craters were scanned with a Micro CT (SkyScan 1072, Aartselaar, Belgium). Software analysis of the scanned samples provided a volumetric measurement of the resorption craters on the mandibular molar cementum surface.

RESULTS

Resorption sites were found in the control samples, especially on the distal surfaces; this could be attributed to normal physiological tooth drift. Resorption sites were significantly (P <.05) increased in the groups receiving orthodontic tooth movement.

CONCLUSIONS

Fluoride reduces the size of resorption craters, but the effect is variable and not statistically significant (P >.05).

True incisor intrusion attained during orthodontic treatment: A systematic review and meta-analysis

INTRODUCTION

The purpose of this meta-analysis was to quantify the amount of true incisor intrusion attained during orthodontic treatment.

METHODS

Electronic databases (PubMed, Medline, Medline In-Process & Other Non-Indexed Citations, all EBM reviews [Cochrane Database of Systematic Reviews, ASP Journal Club, DARE, and CCTR], Embase, Web of Science, and Lilacs) were searched with the help of a senior health sciences librarian. The goal was to identify clinical trials that assessed true incisor intrusion through cephalometric analysis and factored out craniofacial growth when required. From the selected abstracts, original articles were retrieved, and their references were hand searched for missing articles.

RESULTS

Twenty-eight articles met the initial inclusion criteria, but 24 were rejected because they did not quantify true incisor intrusion or factor out normal growth impact when required. The remaining 4 articles showed that true incisor intrusion is attainable (0.26 to 1.88 mm for the maxillary incisors and -0.19 to 2.84 mm for the mandibular incisors) but with large variability depending on the appliance used. A meta-analysis with results from the 2 articles that used the segmental technique was completed. The combined mean estimates of intrusion and 95% CI were 1.46 mm (1.05-1.86 mm) for the maxillary incisors and 1.90 mm (1.22-2.57 mm) for the mandibular incisors.

CONCLUSIONS

True incisor intrusion is achievable in both arches, but the clinical significance of the magnitude of true intrusion as the sole treatment option is questionable for patients with severe deepbite. In nongrowing patients, the segmented arch technique can produce 1.5 mm of incisor intrusion in the maxillary arch and 1.9 mm in the mandibular arch.

Exploring the third dimension in root resorption

OBJECTIVE

To review and investigate the validity of various 2D quantitative measurement techniques, and to explore the third dimension of root resorption.

DESIGN

A review of the literature involving various quantitative evaluation of root resorption.

RESULTS

Quantitative evaluation of resorption using radiographs has proven to be highly inaccurate because of magnification errors and their inability to be readily repeated and reproduced. Studies using histology sections of samples have proven to be laborious and technique sensitive. Inherent parallax errors and loss of material in data transfer have denied the true understanding of this 3D event.

CONCLUSION

With the evolution in computing technology and digital imaging, the vision of evaluating the extent of root resorption in 3D has materialized. It was demonstrated that 3D volumetric quantitative evaluation of root resorption craters was feasible and its accuracy and repeatability was high.

Mechanical stress generated by orthodontic forces on apical root cementum: a finite element model

OBJECTIVES

1) To determine the mechanical stress generated at the root apex during different types of tooth movement using a finite element model of an ideal, human maxillary central incisor. 2) To determine the relationship of thickness of cementum and the magnitude of mechanical stress at the root apex.

DESIGN

Computer simulation.

SETTING AND SAMPLE POPULATION

Not applicable, computer simulation.

EXPERIMENTAL VARIABLES

Tooth and investing tissue layers (enamel, dentin, cementum, pulp, periodontal ligament, and alveolar bone).

OUTCOME MEASURE

Von Mises and maximum principal stresses.

RESULTS

Increasing the apical thickness of cementum increases the amount of mechanical stress.

CONCLUSION

A finite element model incorporating all layers of a human maxillary central incisor has been developed. This model was used to determine the location and magnitude of mechanical stress generated for all regions of the tooth, PDL, and enclosed alveolar bone, when orthodontic forces are applied to the tooth. Mechanical stresses were found to increase at the root apex with increasing thickness of apical cementum.

Root resorption caused by orthodontic treatment: an evidence-based review of literature

Literature on apical root shortening published in the 1990s is reviewed. Three categories were assigned: sample-based clinical studies, clinical case reports, and animal model studies. Great variability for root shortening was reported, including resorption experienced by individuals who had never undergone orthodontic treatment. Some studies attempted to predict severe resorption whereas others compared different types of treatment. Included are several histological studies of teeth that were moved in humans. Very few of the sample-based clinical studies were prospective, randomized clinical trials. Data from a study that the author was involved in was used to estimate the percentage of patients who would experience different amounts of apical root shortening. It was estimated that 5% of the patients treated would experience more than 5 mm of root shortening.

Analysis of stress in the periodontium of the maxillary first molar with a three-dimensional finite element model

The aim of this study was to simulate the stress response in the periodontium of the maxillary first molar to different moment to force ratios, and to determine the moment to force ratio for translational movement of the tooth by means of the finite element method. The three-dimensional finite element model of the maxillary first molar consisted of 3097 nodes and 2521 isoparametric eight-node solid elements. The model was designed to dissect the periodontal ligament, root, and alveolar bone separately. The results demonstrate the sensitivity of the periodontium to load changes. The stress pattern in the periodontal ligament for a distalizing force without counterbalancing moments showed high concentration at the cervical level of the distobuccal root due to tipping and rotation of the tooth. After various counterrotation as well as countertipping moments were applied, an even distribution of low compression on the distal side of the periodontal ligament was obtained at a countertipping moment to force ratio of 9:1 and a counterrotation moment to force ratio of 5:1. This lower and uniform stress in the periodontal ligament implies that a translational tooth movement may be achieved. Furthermore, high stress concentration was observed on the root surface at the furcation level in contrast with anterior teeth reported to display high concentration at the apex. This result may suggest that the root morphology of the maxillary first molar makes it less susceptible to apical root resorption relative to anterior teeth during tooth movement. The stress patterns in the periodontal ligament corresponded with the load types; those on the root appeared to be highly affected by bending and the high stiffness of the root.

Etiology and sequelae of root resorption

This article reviews the current status of investigation into apical root resorption within the context of orthodontic treatment. Treatment and patient factors that have traditionally been investigated are discussed, along with the results of current research in this area. The need for rethinking traditional research strategies in the quest for identifying both control and causative mechanisms is explored. Finally, proposals for key areas of future interest are highlighted.