Incidence Of Root Resorption Research Articles

Three consecutive days of application of LED therapy is necessary to inhibit experimentally induced root resorption in rats: a microtomographic study.

Previous studies have suggested that phototherapy may modulate orthodontic tooth movement and the incidence of root resorption. We aimed to identify a minimal dose-response relationship to LED therapy with regard to orthodontic tooth movement (OTM) and root resorption in rats. Forty-eight male Wistar rats were divided into six groups with equal and random distribution: control (C) no intervention; three daily LED irradiation (CLED); submitted only to OTM (RR); OTM and LED irradiation on the first day (LED1); OTM and two LED irradiation on the first and second days (LED2); and OTM and three LED irradiation on the first, second, and third days (LED3). Orthodontic appliance was installed in groups RR, LED1, LED2, and LED3 to promote OTM. Animals from groups CLED, LED1, LED2, and LED3 received LED therapy (940nm, 4J, 4J/cm2) according to each group of treatment. After 7days, all the animals were sacrificed. The jaws were fixed and scanned with microtomography (micro-CT). The micro-CT images were reconstructed on 2D and 3D models. These models were used to identify and measure root resorption number and dimensions (diameter, depth, and volume). The distance between the first and second molars was used to verify tooth displacement. The results showed that LED3 group had significantly lower number of root resorption. The root resorption dimensions (diameter and depth) had no significant differences among the experimental groups. LED3 group had significant tooth displacement in relation to C and CLED groups. In conclusion, three daily LED therapy doses are required to inhibit root resorption after appliance of orthodontic forces.

Tissue responses resulting from tooth movement surgically assisted by corticotomy and corticision in rats.

To compare the histological responses in corticotomy- and corticision-assisted tooth movement. Ninety Wistar rats were divided into three groups: C (control-tooth movement only), CT (tooth movement + corticotomy), and CI (tooth movement + corticision). Surgeries were performed on the vestibular and lingual cortical bone of the maxillary first molar. Tooth movement was carried out with nickel-titanium closed coil springs having a force of 30 g. The rats were sacrificed at 3, 14, and 28 days. To evaluate the number of osteoclasts and amount of root resorption, a tartrate-resistant acid phosphatase stain was used. Hematoxylin and eosin staining was performed for areas of hyalinization, and the organic bone matrix was stained with picrosirius. The CT group showed a greater number of osteoclasts than did the C group on day 3 (P < .05). At the same time point, the CT and CI groups showed a delayed onset of organic bone matrix remodeling and a lower incidence of root resorption than did the C group (P < .05). There were also fewer hyalinization areas in the CI group than in the C group on day 3 (P < .05). Corticotomy effectively increased bone resorption during the early stages of tooth movement, but this increase was not observed for corticision. The surgical procedures did not accelerate organic bone matrix remodeling. Corticotomies and corticisions decreased the risk of root resorption only during the early stages of movement. Corticision reduced the level of hyalinization, while corticotomy did not.

Influence of enamel matrix derivative on healing of root surfaces after bonding treatment and intentional replantation of vertically fractured roots.

The objectives of this study were to histopathologically evaluate cementum regeneration on root surfaces when an enamel matrix derivative (EMD) was used to bond a vertically fractured root and to evaluate the effectiveness of EMD in inhibiting root resorption. A total of 40 roots from 24 maxillary premolars in beagles were used. The root was vertically fractured using a chisel and mallet. Super-Bond was then used to bond the fractured root. In the experimental group, the root surface was treated with ethylenediaminetetraacetic acid and an EMD. The control group received no treatment. The root was then replanted in its original location. Histopathological observation and measurement using image-analyzing software were carried out after 8 weeks. In the experimental group, shallow resorption cavities developed on the root planed surfaces with new acellular cementum appearing over them. In the control group, no new cementum was seen on the planed surfaces, and there was connective tissue joining the roots. In some of the samples, resorption and multinucleated giant cells were seen. The experimental group showed a significantly larger volume of cementum formation (P < 0.001), and the volume of root resorption was significantly smaller (P = 0.004). When bonding and replanting tooth roots after a vertical fracture, the application of EMD was effective in regenerating cementum on root surfaces from which periodontal ligament had been lost in the area around the fracture line and in reducing the incidence of root resorption.

Comparison of the changes of alveolar bone thickness in maxillary incisor area in extraction and non-extraction cases: computerized tomography evaluation

To compare, through computed tomography, alveolar bone thickness changes at the maxillary incisors area during orthodontic treatment with and without tooth extraction. Twelve patients were evaluated. They were divided into 2 groups: G1--6 patients treated with extraction of right and left maxillary first premolars, with mean initial age of 15.83 years and mean treatment length of 2.53 years; G2--6 patients treated without extraction, with mean initial age of 18.26 years and mean treatment length of 2.39 years. Computed tomographies, lateral cephalograms and periapical radiographs were used at the beginning of the treatment (T1) and 18 months after the treatment had started (T2). Extraction space closure occurred in the extraction cases. Intragroup and intergroup comparisons were performed by dependent and independent t test, respectively. In G1, the central incisor was retracted and uprighted, while in G2 this tooth showed vestibularization. Additionally, G1 presented a higher increase of labial alveolar bone thickness at the cervical third in comparison with G2. The incidence of root resorption did not present significant differences between groups. There were no changes in alveolar bone thickness when extraction and nonextraction cases were compared, except for the labial alveolar bone thickness at the cervical third of maxillary incisors.

A clinical survey for the association between root resorption incident to orthodontic treatment and host factors

Introduction: The purpose of this study was to clarify the prevalence and degree of root resorption induced by force application during orthodontic treatment. Association between the root resorptio...

Association between root resorption incident to orthodontic treatment and treatment factors

Sir, We read with interest the article about the association between root resorption and orthodontics by Motokawa et al. (2012). The prevalence and degree of root resorption induced by orthodontic treatment in association with treatment factors was well described by the authors. The results of their study indicated that orthodontic treatments with extractions, long-term use of a multiloop edgewise arch-wire appliance and elastics, treatment time, and distance of tooth movement are …

Clinical survey of the association between root resorption incident to orthodontic treatment and host factors

Clinical survey of the association between root resorption incident to orthodontic treatment and host factors

Association between root resorption incident to orthodontic treatment and treatment factors

The purpose of this study was to clarify the prevalence and degree of root resorption induced by orthodontic treatment in association with treatment factors. The files of 243 patients (72 males and 171 females) aged 9-51 years were randomly selected from subjects treated with multi-bracket appliances. The severity of root resorption was classified into five categories on radiographs taken before and after treatment. The subjects were divided into extraction (n = 113 patients, 2805 teeth) and non-extraction (n = 130 patients, 3616 teeth) groups and surgical (n = 56 patients, 1503 teeth) and non-surgical treatment (n = 187 patients, 4918 teeth) groups. These subjects were also divided into two or three groups based on the duration of multiloop edgewise archwire (MEAW) treatment, elastic use, and total treatment time: 0 month (T1; n = 184 patients, 4831 teeth), range 1-6 months (T2; n = 37 patients, 994 teeth), more than 6 months (T3; n = 22 patients, 596 teeth); range 0-6 months (n = 114 patients, 3016 teeth) more than 6 months (n = 129 patients, 3405 teeth); range 1-30 months (n = 148 patients, 3913 teeth) and more than 30 months (n = 95 patients, 2508 teeth). The prevalence of overall and severe root resorption evaluated by the number of subjects and teeth was compared with a chi-square test. A Student's t-test for unpaired data was used to determine any statistically significant differences. The prevalence of severe root resorption based on the number of teeth was significantly higher in the group with extractions (P < 0.01). Longer use of a MEAW appliance and elastics also produced a significantly higher prevalence of root resorption (P < 0.05). On the other hand, the prevalence of severe root resorption was not significantly different between the subjects treated with or without surgery, but there was a significant increase when treatment time was prolonged (P < 0.05). A significant difference was found in the amount of root movement of the upper central incisors and the distance from their root apices to the cortical bone surface (P < 0.05). These are regarded as essential factors in the onset of root resorption. These results indicate that orthodontic treatment with extractions, long-term use of a MEAW appliance and elastics, treatment time, and distance of tooth movement are risk factors for severe root resorption.

Root and Bone Response to the Proximity of a Mini-Implant under Orthodontic Loading

To determine the histological reaction of the root and bone as a mini-implant approaches the root. Two kinds of mini-implants were inserted into the buccal alveolar bone of 4 beagles (2 males and 2 females). The specimens were classified as the near-root group, the PDL contact group, the root contact group, and the root perforation group. Cementum resorption, dentin resorption, cementum repair, cementum growth, ankylosis, root cracking, and root fracture were assessed as the implant neared the root. The incidence of root resorption increased when the mini-implant was less than 0.6 mm from the root in the near-root group and PDL contact group. Root cracking and root fracture occurred in the root contact group and root perforation group. Bone resorption and ankylosis were observed in some specimens. However, some specimens of the PDL contact group and root contact group had cementum growth or little root resorption despite proximity to the root. In the root perforation group, root resorption and ankylosis occurred on the side opposite the insertion. There is a risk of root contact and severe tissue damage from a thick mini-implant and the drilling procedure, either of which can induce root resorption or ankylosis. Use of smaller mini-implants may reduce root contact and tissue damage. However, the small mini-implant may need enhancement of its stability.

Age-dependent external root resorption during tooth movement in rats

Objective. To investigate the effect of age on root resorption and distribution along different parts of the root during prolonged light force application. Material and methods. Orthodontic appliances were placed in two groups of 30 rats (one group 6 weeks old, the other 9–12 months old), with contralateral sides as controls. Groups of animals were killed at 1, 2, 4, 8, and 12 weeks. At the study site, incidence was counted as either 1 (with resorption) or 0 (without); severity was measured as the summed length of all resorption lacunae as a percentage of study total root length. Results. Young and adult rats had the same incidence of root resorption in the early phase (<4 weeks), and both increased in the late phase (4–12 weeks) to the same level. Severity of resorption increased with prolonged tooth movement only in adult rats. However, there was no age-related difference in either the early or the late phase. In both groups, the middle part of the root had the highest incidence of resorption; the most severe resorption occurred exclusively at this part. Conclusion. Orthodontic intervention even with light forces increased both the incidence and severity of root resorption, the more so in the middle part of the root. Adult rats had increased incidence and severity with prolonged tooth movement.

The Displaced Maxillary Canine—a Retrospective Study

The re-alignment of retained maxillary canines was studied in relation to the degree of displacement in panoramic radiographs, mesiodistal root deviations, length of treatment and side-effects. The aim was then to determine whether the decision between surgical removal and orthodontic re-alignment can be made on the basis of panoramic radiographs alone. Forty-seven panoramic radiographs with 59 displaced canines were used to determine their distance and inclination to the occlusal plane (similar to the method described by Dausch-Neumann [8]), the position of the crown tip, and the frequency of mesiodistal root deviations. The length of active treatment was recorded and analyzed statistically in relation to the degree of displacement and incidence of root deviation. Finally, pre- and post-therapeutic panoramic radiographs were compared to determine the incidence of root resorptions and marginal bone defects. The mean values for the angle of inclination and the distance of the maxillary canines from the occlusal plane were 57.4 degrees (+/- 14.3 degrees ) and 10.5 mm (+/- 3.8 mm), respectively. In 21 canines, the crown tips projected most frequently between the central and lateral incisors. Twelve canines presented root deviations. Treatment lasted an average of 1.9 years (+/- 0.7 years). No correlation was found between the treatment time and the canine's distance from the occlusal plane (r = 0.03), its angle of inclination (r = 0.06), position of the crown tip (r = 0.12), or root deviation (r = -0.07). Root resorptions were found in nine canines (15.3%) and marginal bone defects in 24 canines (40.7%). Fifty-nine retained maxillary canines, some showing extreme displacement, were re-aligned in an average of 1.9 years. There was no correlation between the degree of canine displacement in the panoramic radiographs or the incidence of mesiodistal root deviations and active treatment time. For this reason, the indication to remove displaced maxillary canines should not be taken from panoramic radiographs alone.

Effects of local administration of clodronate on orthodontic tooth movement and root resorption in rats

Clodronate, a non-N-containing bisphosphonate, strongly inhibits bone resorption and also has anti-inflammatory properties. The purpose of this study was to examine the effect of the local administration of clodronate on orthodontic tooth movement. Both the right and left upper first molars of 26 7-week-old male Wistar rats were moved buccally with a standardized expansion spring. Clodronate solution was injected into the sub-periosteum area adjacent to the left upper molar every third day during the experimental period. The right first molar served as the control. Local injection of clodronate caused a significant (P < 0.001) and dose-dependent reduction in tooth movement in the rats. The number of osteoclasts on the clodronate-injected side was significantly less (P < 0.01) than on the control side. Local clodronate also inhibited root resorption incident to tooth movement. These results suggest that localized use of clodronate could be a useful therapeutic adjunct in orthodontic treatment.

Histological and histochemical quantification of root resorption incident to the application of intrusive force to rat molars.

This study was conducted to investigate the nature of root resorption resulting from intrusive forces applied to the rat lower molars, by means of histological and histochemical techniques with tartrate resistant acid phosphatase (TRAP). Thirty-eight 13-week-old Wistar strain male rats were used. Intrusive force was created by a fixed appliance which was adjusted to exert an initial force of 50 g for the duration of 1, 2, and 3 weeks. The degree of root resorption and distribution of TRAP positive cells were evaluated. On the root surface, the TRAP positive scores were low in the apical regions. Significant differences in the scores were found in the inter-radicular region of the roots between the experimental and control groups for the 2- and 3-week groups. More active resorption of bone occurred during the experimental period, as denoted by greater TRAP positive scores on the bone than on the root surface. Root resorption scores in the apical root region were larger in the 2- and 3-week groups than in the 1-week group. Significant differences in the root resorption scores were also found between the 1- and 3-week groups in the inter-radicular region, indicating that intrusive force application of a longer duration may lead to a higher frequency of root resorption. It is shown that, irrespective of the level of TRAP positive cells and root resorption scores, the degree of root resorption activity is higher in the apical root region than in the inter-radicular area. These results indicate that cellular cementum may be resorbed more easily because of its richer organic components and low mineralized structure.

An evaluation of root resorption incident to orthodontic intrusion

A new radiographic method was developed for measuring changes in root length. With this technique, orthodontic intrusion was investigated as a potential cause of apical root resorption of maxillary incisors. The experimental group consisted of 17 patients with excessive overbite who were treated with a Burstone-type intrusion arch, which delivered a low level of force (about 15 gm per tooth). A control group was made up of 17 patients in full-arch fixed appliances who were randomly selected. After a period of approximately 4 months, the intrusion group had only slightly more root resorption than the controls, 0.6 mm versus 0.2 mm (statistically significant difference). Intrusion measured at the center of resistance of the central incisor averaged 1.9 mm. The amount of resorption was not correlated with the amount of intrusion. A weak correlation, r = 0.45, was found between resorption and movement of the apex (i.e., in addition to intrusion, there was often palatal root movement). Results of this study seem to indicate that intrusion with low forces can be effective in reducing overbite while causing only a negligible amount of apical root resorption. (Am J Orthod Dentofac Orthop 1996;109:543-8.)

The finite element analysis of stress in the periodontal ligament when subject to vertical orthodontic forces.

In the past, vertical intrusive movement of teeth has been considered difficult and most routine clinical vertical movement of teeth has been confined to extrusion. It has been suggested that attempts at intrusion may result in an increased incidence of root resorption and also in occasional devitalization. The displacement and resulting stress fields associated with such treatment can be successfully studied using the finite element method. In the case being considered initial movements are known to be small; therefore, the assumption in the study that the material behaves linear-elastically is considered to be reasonable. This study of vertical tooth movement demonstrated that the maximum cervical margin stress in the periodontal ligament was 0.0046 N/mm2, whilst the highest apical stress was 0.00205 N/mm2 when intrusive and extrusive forces of 1 Newton were applied to the buccal surface of the crown of a tooth model. These stresses were evaluated in the light of previous studies and found to be within the suggested clinical optimum level. However, the periodontal stress distribution following orthodontic loading within this three-dimensional finite element model was found to be highly complex.

The initial phase of orthodontic root resorption incident to local compression of the periodontal ligament.

The present light microscopic investigation was undertaken in order to study the initial phase of orthodontic root resorption in areas of pressure and, more specifically, to focus on the first cells that penetrate the root surface. Twenty-one upper first molars (rats) and 31 lower first molars (mice) were moved mesially by a fixed orthodontic appliance. The experimental periods were 1, 2, 3, 4, and 5 days in rats, and 1, 2, 3, 4, 5, 6, 7, and 8 days in mice. Tartrate-resistant acid phosphatase (TRAP) and Haematoxylin Eosin (H&E) stains were used. Root resorption related to a hyalinized zone showed a consistent pattern: Root resorption started in the circumference of the necrotic hyalinized tissue. In the central parts of the hyalinized zone frontal root resorption occurred 3-4 days later than in the periphery. Indications that the mechanisms for circumferential and central resorption differed was the reason for presenting only the periphery stage in this paper. The initial penetration of cells into precementum/cementum occurred at the peripheries or at a short distance from the peripheries of the hyalinized zone. These cells were TRAP-negative, indicating that they were not clasts or clast precursors. Before this happened TRAP-negative macrophage-like cells were observed at the borderline between the hyalinized tissue and vital periodontal membrane (PM). TRAP-positive cells were first observed in the bone marrow spaces. During the later stages mono- and multi-nucleated TRAP-positive cells were participating in active removal of the hyalinized tissue toward the root surface, and in resorption of cementum and dentine.

Replantation: An analysis of 29 teeth

The results of replantation of 29 teeth are described. Maxillary incisors constituted 85% of 27 permanent teeth. The period between avulsion and replantation ranged from within an hour to 86 days, but the actual extraoral period was within 5 hours in all but one case. Nineteen of the 27 permanent teeth were functioning for 7 months to 6 years and 7 months postoperatively. Root resorption was the cause of tooth loss in five cases. The incidence of root resorption seemed to increase with the increase of the extraoral period, but it was not affected by the period between avulsion and replantation, the condition of supporting tissues, the degree of root formation, and the type and period of splinting, indicating multiple factors involved in determining the prognosis of replanted teeth. In conclusion, every effort should be made to preserve avulsed teeth even in unfavorable conditions.

The case for postoperative orthodontics in orthognathic surgery

In patients with orthognathic problems, in whom a combination of surgery and orthodontics is required, it seems to us better to defer orthodontic treatment until after surgery has been completed and a possible relapse tendency has petered out. This conclusion is reached on the basis of arch instability and the incidence of root resorption as reported in the orthodontic literature. The soundness of "permanent retention" after orthodontic therapy is questioned. The author's concepts are illustrated with a few case reports.

Autogenous free tooth transplantation in man by a 2-stage operation technique. A longitudinal intra-individual radiographic assessment

Insufficient nutrition to the root surface of autotransplanted mature human teeth after transplantation could be an explanation for the high rates of complications such as root resorption and loss of the tooth transplant. Insufficient nutrition is suggested as being due to the distance between the recipient site tissue and the root surface, and the presence of a blood-clot between the tissues. Improved nutrition could be achieved by transplanting into contact with the vascularised connective tissue of a healing wound. To test this hypothesis, a series of human teeth with fully developed roots were autotransplanted to recipient sites prepared and left to heal for 14 days before transplantation. This study is a follow-up of 57 transplants with a minimum observation time of 1 year. Periodic radiographic examinations of the teeth were performed up to 5 years after transplantation. The results presented, showed a lower incidence of root resorption and extractions than previously reported for teeth with fully developed roots.

The role of the necrotic periodontal membrane in cementum resorption and ankylosis.

Abstract Teeth replanted with non‐vital periodontal membranes demonstrate a high incidence of root resorption and ankylosis. It has been suggested that necrotic periodontal membrane remnants actively stimulate resorption of the resistant cementum layer. The aim of this study was to examine resorption and ankylosis patterns following replantation of teeth with chemically denuded root surfaces and, by extrapolation from these data, to suggest a role for the necrotic periodontal membrane in resorption and ankylosis.Monkey incisors were replanted after endodontic therapy and immersion in 10% sodium hypochlorite. Teeth were either examined with scanning electron microscopy at intervals from 1 day to 8 wk, or subjected to light microscopic examination, using a morphometrical evaluation technique, at 8 wk post‐replantation.Only a few macrophage‐like cells, in relation to shallow resorption lacunae, were observed by 8 wk. Histologically, the alveolar bone had approached an apparently intact cementum surface in 93% of the morphometrically recorded points. This bone appeared to lie in close approximation to the cementum surface.Denuding the root surface of periodontal membrane prior to replantation demonstrated the resistance of the cementum to colonization and resorption in the absence of stimulation from necrotic periodontal membrane remnants. Furthermore, it revealed that bone replacing the periodontal membrane space grew from the alveolus towards the cementum, to which it appeared unable to fuse due to the absence of significant resorption. Thus, removal of a non‐vital periodontal membrane may result in slower destruction of tooth substance following replantation of teeth with severely damaged periodontal membranes.