The effect of alveolar decortication on orthodontically induced root resorption

ObjectiveTo determine the effect of alveolar decortication on orthodontically induced root resorption.Materials and MethodsA total of 24 male Wistar rats (14 week old) were used. The rats were randomly divided into one of the following three groups: group 1 (control group), orthodontic tooth movement (OTM) for 2 weeks; group 2, OTM for 2 weeks + two alveolar decortications (2AD); group 3, OTM for 2 weeks + four alveolar decortications (4AD). The first molar was moved mesially for 2 weeks. Micro computed tomography was used to analyze root volume. In addition, histological sections were stained with Tartrate Resistant Acid Phosphatase (TRAP) to quantify the osteoclast number.ResultsThe buccal root volume in OTM + 4AD group was decreased by 8.92% and 6.11% when compared with the OTM-only group and OTM + 2AD group, respectively. Similarly, the other four root volumes in the OTM + 4AD group was decreased by 8.99% and 5.24% when compared with the OTM-only group and OTM + 2AD group, respectively. There was a decrease in buccal root density in the OTM + 4AD group by 4.66% and 3.56% when compared with the OTM-only group and the OTM + 2AD group, respectively. In addition, there was an increase in the number of osteoclasts by 195.73% and 98.74% in OTM + 4AD group in comparison with the OTM and OTM + 2AD group.ConclusionsThe amount of orthodontically induced root resorption was positively correlated with the extent of surgical injury used to accelerate orthodontic tooth movement.     

Phototherapy is unable to exert beneficial effects on orthodontic tooth movement in rat molars

Objectives:To investigate the effects of irradiation lasers and light-emitting diode (LED) light on root resorption in rat molars during orthodontic tooth movement (OTM).Materials and Methods:Twenty-one 12-week-old Wistar male rats were divided into three groups: OTM only (control [CG]), OTM and LED irradiation (DG), and OTM and low laser irradiation therapy (LG). The distance between the first and second molars was used to evaluate the amount of tooth movement. The mesial surfaces of the distopalatal roots were analyzed by scanning electron microscopy, and the area of the resorption was calculated.Results:Statistical analysis showed a decreased amount of tooth movement in the exposed DG or LG compared with CG, which was statistically significant (P = .031 and P = .004, respectively). However, when the DG and LG groups were compared, no statistically significant differences were found (P = .504). The root resorption areas were similar between CG and DG. However, statistically significant differences were found between LG and CG (P = .014) and LG and DG (P = .038).Conclusions:Phototherapy did not enhance tooth movement, while infrared laser irradiation did increase root resorption.     

Short-term effects of nicotine on orthodontically induced root resorption in rats

Objective:To investigate the effect of nicotine exposure on root resorption in an in vivo rat model of orthodontic tooth movement (OTM), and its association with odontoclastogenesis and receptor activator of nuclear factor-kappa B ligand (RANKL) expression.Materials and Methods:Forty-eight 10-week-old male Wistar rats were divided into three groups. The negative control group was untreated. The left maxillary first molars in the nicotine-treated group and the positive control group received OTM with an initial force of 0.6 N in the mesial direction. Also, the nicotine-treated group received intraperitoneal injection of nicotine at 7 mg/kg per day. After 21 days, the rats were humanely killed. Eight rats from each group were randomly chosen for crater volume analysis by micro-computed tomography. For the remaining eight rats in each group, specimen slices were generated for histologic examination to determine the odontoclast number and the mean optical density value of RANKL.Results:The resorption volumes in the nicotine-treated group were significantly larger than those in the control groups. Also, the nicotine-treated group displayed significantly higher number of odontoclasts and elevated RANKL expression compared to the control groups.Conclusions:In an in vivo rat model, nicotine exposure promotes odontoclastogenesis and RANKL expression, evoking aggravated root resorption during OTM.     

Lithium chloride reduces orthodontically induced root resorption and affects tooth root movement in rats

Objective:To investigate the influence of lithium chloride (LiCl) on orthodontic tooth movement (OTM), orthodontically induced root resorption (OIRR), and bone morphometry.Materials and Methods:Ten-week-old female Sprague Dawley rats (n = 32) were divided into four groups based on the concentration of LiCl administered daily per kilogram body weight: 0 (control group), 0.32, 0.64, and 1.28 mM/kg body weight. The maxillary left first molars were moved mesially by a 10 cN coil spring for 14 days. Micro-computed tomography, scanning electron microscope, and scanning laser microscope images were taken to measure the amount of OTM, the volume of OIRR, and bone morphometry.Results:OIRR clearly decreased depending on the amount of LiCl administered, although OTM moderately decreased. The tooth inclined mesially and the root apex moved distally in the control and 0.32 mM groups. On the other hand, the tooth inclination angle became smaller and the root apex moved mesially in the 0.64 and 1.28 mM groups. In bone morphometry, the cortical bone mineral content and bone volume increased because of LiCl administration, and the trabecular bone measurements decreased. OIRR negatively correlated to the cortical bone measurements, and the amount of OTM significantly correlated to the cortical bone morphometry.Conclusions:In rats, LiCl reduced OIRR, which induced mesial movement of the tooth root apex. OIRR positively correlated to cortical bone morphometry.     

Effects of different types of tooth movement and force magnitudes on the amount of tooth movement and root resorption in rats

Objective:To investigate differences in the amount of tooth movement and root resorption that occurred after tipping and bodily movement of the maxillary first molar in rats.Materials and Methods:Ten-week-old female Wistar rats were divided into two groups according to type of tooth movement and subdivided into four subgroups according to the magnitude of applied force. Nickel-titanium closed-coil springs exerting forces of 10, 25, 50, or 100 g were applied to the maxillary left first molars to induce mesial tooth movement. We designed a novel orthodontic appliance for bodily tooth movement. Tooth movement distance and root resorption were measured using microcomputed tomography and scanning electron and scanning laser microscopy.Results:The amount of tooth movement in the bodily tooth movement group was less than half that in the tipping tooth movement group. The greatest amount of tooth movement occurred in the 10-g tipping and 50-g bodily tooth movement subgroups, and the amount of tooth movement decreased with the application of an excessive magnitude of force. Conversely, root resorption increased when the heavier orthodontic force was applied in both groups. Root resorption in the tipping tooth movement group was approximately twice that in the bodily tooth movement group.Conclusions:Root resorption in the tipping tooth movement group was more pronounced than that in the bodily tooth movement group. Although the amount of tooth movement decreased when extremely heavy forces were applied, root resorption increased in both the tipping and bodily tooth movement groups in rats.     

The effect of prostaglandin E2 and calcium gluconate on orthodontic tooth movement and root resorption in rats

Possible modifications in orthodontic tooth movement (OTM) and root resorption as a result of local injections of prostaglandin E2 (PGE2) alone and with calcium gluconate (Ca) formed the aim of the present study. Twenty-four 8-week-old male Wistar rats were selected and randomly divided into three groups of eight. Both quadrants of the upper jaws of the first group of animals were used; therefore this group comprised two groups: control and normal. The upper left first molars of these eight animals were not placed under orthodontic force and received no injection, to serve as the normal group, considered for root resorption comparison only. The control group had localized submucosal injections of normal saline on the buccal side of the upper right first molar. In the third group, 0.1 ml of 1 mg/ml PGE2 was injected at the same site and the fourth group received an intraperitoneal injection of 200 mg/kg Ca (10%) in addition to the PGE2. All the injections were performed on days 0 and 7. The orthodontic appliance consisted of a closed coil spring ligated to the upper right first molar and incisor, exerting a force of 60 g during the 21-day experimental period, after which the animals were sacrificed. Palatal halves were removed for histological examination and for calculation of the amount of root resorption. Statistical analysis of data showed a significant (P < 0.05) acceleration in OTM after PGE2 injection compared with the control group. The addition of Ca reduced OTM but a significant increase (P< 0.05) was still recorded. A significant difference (P < 0.05) in root resorption was only observed between the PGE2 and normal groups. The findings show the importance of calcium ions working in association with PGE2 in stabilizing root resorption while significantly increasing OTM.     

Effects of vitamin D deficiency on the rate of orthodontic tooth movement: An animal study

Bone remodeling and orthodontic tooth movement (OTM) are controlled by certain essential molecules, one of which is vitamin D. Increased levels of vitamin D have been associated with increased rates of OTM. The purpose of this study was to determine the effect of vitamin D deficiency on the rate of OTM, and to determine their association after applying orthodontic forces.Materials and MethodsWistar rats were divided into two groups: control group with average vitamin D levels and experimental group with induced vitamin D deficiency. Orthodontic appliances were fixed to initiate tooth movement. Distance between the reference teeth were measured in millimeters on day zero, and repeated every 7 days, till day 21.ResultsA significant difference within the experimental group was found; as well as within the control group, there was also no significant interaction between time and the type of group.ConclusionThe rate of Orthodontic tooth movement was not affected by induced vitamin D deficiency in rats.     

Influence of nicotine on orthodontic tooth movement: A systematic review of experimental studies in rats

ObjectiveThe objective of this systematic review was to assess the impact of nicotine administration on orthodontic tooth movement (OTM).MethodsA systematic search was conducted in PubMed, Scopus, EMBASE, MEDLINE (OVID) and Web of Knowledge databases and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Studies evaluating the influence of nicotine on OTM, and with the presence of a control group (OTM without nicotine administration), were included. Quality assessment of the selected studies was performed following the Animal Research Reporting in Vivo Experiment (ARRIVE) guidelines.ResultsSix of the initially identified 108 articles fulfilled the inclusion criteria and were selected. All included studies were performed in male rats, which underwent OTM with or without nicotine administration. Since there was a variation among the included studies regarding nicotine dosage and the duration and magnitude of force application during OTM only a qualitative analysis could be performed. The studies reported that nicotine administration accelerated OTM by inducing alveolar bone resorption around the moving teeth. It was also found that nicotine increased root resorption during experimental OTM. More standardized animal research or clinical studies are warranted to further evaluate the impact of nicotine on OTM.ConclusionsOn an experimental level, nicotine exposure in rats jeopardizes OTM by increasing alveolar bone loss and root resorption. From a clinical perspective, further studies are needed to assess the impact of habitual use of tobacco products on OTM.     

应用Micro-CT研究矫治力对正畸牙齿移动及牙根吸收的影响

目的：了解不同矫治力作用下大鼠牙齿移动距离及牙根吸收情况,探索应用Micro?CT研究正畸牙齿移动过程中矫治力对牙根吸收的影响。方法10周龄健康雄性SD大鼠64只（220~270 g）,分别施以10 g （10 g力组）、30 g力（130 g力组）拉右侧上颌第一磨牙向近中移动建立实验动物模型,以对侧同名牙为对照牙。于加力后第3、7、14、28天处死动物,使用Micro?CT扫描上颌第一磨牙及周围牙槽骨,测量上颌第一磨牙近中移动距离,计算加力28 d上颌第一磨牙近中根的表面凹陷体积,进行统计学分析。结果加力后发生牙齿移动,10 g力组在加力14 d内,牙齿移动量小于30 g力组（P =0.039）,在加力28 d时大于30 g力组（P<0.05）。加力28 d,10 g力组、30 g力组的牙根表面凹陷总体积高于对照组（P=0.004）,30 g力组产生的牙根表面凹陷总体积高于10 g力组（P<0.001）。结论 Micro?CT可以对牙齿移动及牙根吸收进行可靠评价及量化分析。加力后28 d,10 g力组移动量较30 g力组大,相应产生牙根吸收较30 g力组少。     

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

Objective:To compare the histological responses in corticotomy- and corticision-assisted tooth movement.Materials and Methods: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.Results: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).Conclusions: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.     

The effect of bone morphometric changes on orthodontic tooth movement in an osteoporotic animal model

Objective:To elucidate the effect of bone morphometric changes on orthodontic tooth movement (OTM) in zoledronic acid–treated ovariectomized rats.Materials and Methods:Twenty-one 10-week-old female Wistar rats were divided into ovariectomy (OVX), OVX with zoledronic acid administration (OVX + ZOL), and sham operation (control) groups. Two weeks after OVX, ZOL administration was initiated. Twelve weeks after OVX, a nickel-titanium closed-coil spring of 25-g force was applied mesially to the maxillary left first molar. In vivo micro–computed tomography (CT) of the left proximal tibia was performed for bone morphometric analysis every 2 weeks after OVX. In addition, OTM was investigated using micro-CT at 0, 12, and 14 weeks after OVX.Results:There were significant differences in the bone mineral content (BMC), bone volume (BV), BMC to tissue volume ratio (BMC/TV), and BV to TV ratio of trabecular bone between the control and OVX groups and also between the OVX + ZOL and OVX groups. In the OVX + ZOL group, increased BMC and BV in the cortical bone and increased bone mineral density (BMD) in the trabecular bone were observed. Interestingly, OTM in the OVX group was almost two times more than that in the control and OVX + ZOL groups. Moreover, OTM was correlated with BMD, BMC, BV, and BMC/TV in the trabecular bone.Conclusions:OVX accelerated OTM, while ZOL suppressed it. OTM demonstrated a significant negative relationship with trabecular bone mass.     

Effects of bone regeneration materials and tooth movement timing on canine experimental orthodontic treatment

Objectives:To evaluate the effects of bone regeneration materials and orthodontic tooth movement (OTM) timing on tooth movement through alveolar bone defects treated with guided bone regeneration (GBR) utilizing xenografts (Bio-Oss) and alloplast (β-TCP).Materials and Methods:Twenty-four standard alveolar bone defects in six male beagle dogs were treated by GBR using either Bio-Oss or β-TCP (experimental), whereas the control defects were left empty. The defects were further grouped into early or late subgroups, depending on OTM timing after GBR (ie 1 month or 2 months, respectively). Rates of OTM were measured intraorally, while computed tomography scan images were used to assess bone density, alveolar bone height, second premolar displacement, and tipping tendency.Results:Generally, the Bio-Oss early and Bio-Oss late subgroups recorded the lowest amount of tooth movement compared with other modes of GBRs assessed. Before OTM, the control group registered significantly lower bone height compared with the Bio-Oss and β-TCP groups (P < .01). The control group was inferior on bone density and bone height compared with Bio-Oss and β-TCP.Conclusions:The Bio-Oss group had favorable radiologic features (higher alveolar bone level and bone density with less premolar tipping) but showed slower OTM than the control group. The late OTM subgroup had favorable radiologic features and showed faster tooth movement than the early OTM in the β -TCP group.     

The effect of thyroid hormone on orthodontic tooth movement in rats

The major goals of this study were to determine the effects of different doses of thyroxin on the rate of orthodontic tooth movement and the force-induced root resorption. In this study fifty male Sprague--Dawley rats were divided into five groups: a normal group with no intervention; a control group in which appliances were placed and 10 ml/kg i.p./day normal saline was injected; and three thyroxin groups in which appliances were placed and 5, 10 and 20/microgram/kg i.p./day L-thyroxin were administered, respectively. A fixed orthodontic appliance consisting of a 5 mm closed-coil spring was ligated between the maxillary incisor and maxillary first molar to deliver an initial force of 60 gm. The results showed that administration of 20/microgram/kg i.p./day L-thyroxin significantly increased the amount of orthodontic tooth movement (p < 0.001). The extent of root resorption as seen from scanning electron micrographs decreased with thyroxin administration.     

Orthodontic tooth movement in cholestatic and cirrhotic rats

OBJECTIVE: To investigate whether cirrhosis and cholestasis could influence orthodontic tooth movement. DESIGN: Basic science, animal experimental study. SETTING: This study was conducted in the Department of Pharmacology, School of Medicine at Tehran University of Medical Sciences in 2007. PARTICIPANTS: A total of 40 male Sprague-Dawley rats (150-200 g) were divided into five experimental groups: non-operated, cholestatic-sham, cirrhotic-sham, cholestatic and cirrhotic groups. METHODS: An orthodontic appliance, consisting of a 5 mm nickel titanium closed coil spring, was ligated between the maxillary right incisor and first molar of each rat to deliver an initial force of 60 g. The cholestatic and cirrhotic groups underwent a bile duct ligation operation and received an orthodontic appliance for 7 days (cholestatic group) and 28 days (cirrhotic group) after surgery. Two other groups underwent a sham operation and had an orthodontic appliance inserted after 7 (cholestatic-sham) and 28 days (cirrhotic-sham). A fifth control group underwent neither bile duct ligation operation nor sham operation. RESULTS: The cirrhotic group showed significantly increased orthodontic tooth movement (OTM), compared to all other study groups (P<0.001). The mean OTM in the cholestatic group was significantly higher than in the other three groups (two sham groups and unoperated one) (P<0.01). Bone density was also significantly decreased in the bile duct ligated (cirrhotic and cholestatic) groups (P<0.01). CONCLUSION: Our data demonstrated that biliary cirrhosis could cause a significant increase in the OTM and decrease in the bone density in rats, though there was no significant alteration in bone resorption or osteoclasts detected in such animals.     

Comparison of the effects of three surgical techniques on the rate of orthodontic tooth movement in a rat model

Objective:To evaluate the effect of corticotomy and corticision, with and without a full mucoperiosteal flap, on the rate of tooth movement and alveolar response in a rat model.Materials and Methods:Sixty male, 6-week-old Wistar rats were divided into five groups based on surgical procedure, as follows: control (no tooth movement), orthodontic tooth movement (OTM) only, corticotomy, corticision, and corticision with full mucoperiosteal flap (corticision + flap). A force of 10–15g was applied from the maxillary left first molar to the maxillary incisors using nickel-titanium springs. Surgery was performed at the time of appliance placement (day 0), and tooth movement occurred for 21 days. Micro–computed tomography was performed on day 21 to evaluate the amount of tooth movement and alveolar bone parameters. Histomorphometry, including tartrate-resistant acid phosphatase staining, was performed to quantify the osteoclast parameters at day 21.Results:No statistical differences in the amount of OTM, bone volume fraction, and tissue density and the osteoclast parameters were found among all experimental groups.Conclusions:Corticotomy and corticision, with or without a full mucoperiosteal flap, did not show a significant effect on either the OTM magnitude or alveolar bone response.     

Effect of continuous versus intermittent orthodontic forces on root resorption: A microcomputed tomography study

Objectives:To compare the extent of root resorption and the amount of tooth movement between continuous orthodontic force and intermittent orthodontic force that was activated in a similar way to a 4-week orthodontic adjustment period.Materials and Methods:Twenty-five patients who required the extraction of upper first premolars were recruited in this study. A buccally directed continuous force of 150 g was applied to the upper first premolar on one side for 15 weeks. A buccally directed intermittent force (28 days on, 7 days off) of the same magnitude was applied to the contralateral first premolar. The teeth were extracted at the end of the experimental period and processed for volumetric evaluations of resorption craters. The degree of tooth movement and rotation were measured on the study models.Results:Continuous force application displayed significantly higher root resorption volume than the intermittent force application (P < .05), particularly on the buccal and lingual surfaces (P < .05) and the middle third of the root (P < .01). There was more tipping and rotational movement in the continuous force group.Conclusions:In a 4-week orthodontic adjustment period, intermittent force significantly reduced the amount of root resorption compared with continuous force. Although there was less degree of tooth movement with intermittent force, unwanted rotational movement was avoided. This is crucial in patients who are predisposed to orthodontically induced inflammatory root resorption, and the use of this intermittent regimen should be considered.     

Does the floor of the maxillary sinus affect tooth movement for premolar extraction space closure?

Objective

The study investigated orthodontic tooth movement by comparing various horizontal and angular measures of the teeth having different sinus–root relationship (SRR) of patients undergoing first premolar extraction treatment protocols.

Materials and methods

This retrospective cross-sectional study included 45 Taiwanese adult patients, classified as the control group (n?=?15) and the sinus group (n?=?30) according to SRR. The control group had type I SRR (sinus floor above the level connecting the buccal and palatal root apices), whereas the sinus group included patients with type V SRR (the buccal and palatal root displayed apical protrusion into the sinus floor). Morphology was identified using pretreatment orthopantomograms. Lateral cephalometric measurements were conducted before treatment (T1) and at debonding (T2).

Results

Post debonding, there were no statistically significant difference in the two groups. However, the incisors in the control group became marginally more upright than those of the sinus group, and the molars demonstrated tipping movement with minimal anchorage loss in the sinus group than in the control group. The total treatment time was not significantly different between the 2 groups.

Conclusion

The study revealed that the sinus–root relationship does not affect the orthodontic tooth movement. However, a more extensive 3-D study with larger sample size is strongly recommended before coming to any conclusion.

Clinical relevance

The lining of the floor of the maxillary sinus does not affect the orthodontic tooth movement.

     

10种国内期刊正畸牙移动动物模型应用研究的统计分析

目的:了解国内学者对正畸牙移动动物模型的应用现状.方法:利用数据库检索和手动检索相结合方式,数据库检索以清华同方知网技术产业集团出版的CNKI数据库为主要检索工具,对国内10种口腔核心期刊进行调查,检索近10年刊登的文献中有关正畸牙移动动物模型的文献,应用文献计量学方法对其进行统计分析.结果:检出文献86篇,其中69篇是关于正畸牙移动中牙周组织改建机制研究方面(80.25％)；5篇是关于正畸牙移动疼痛机制研究方面(5.81％);7篇与动情周期有关(8.13％)；5篇与正畸牙移动牙根吸收有关(5.81％).结论:目前对于正畸牙移动的研究主要在牙周组织改建方面,而关于正畸疼痛、正畸牙根吸收及生理周期等方面还有待进一步深入研究.     

Effect of Lithothamnium sp and calcium supplements in strain- and infection-induced bone resorption

Objective:To investigate the effect of Lithothamnium sp (LTT) supplement, a calcium-rich alga widely used for mineral reposition, on strain-induced (orthodontic tooth movement [OTM]) and infection-induced bone resorption (periodontal disease [PD]) in mice.Materials and Methods:Mice were divided into two bone resorption models: one with an orthodontic appliance and the other with PD induced by the oral inoculation of Aggregatibacter actinomycetencomitans (Aa). Both groups were fed a regular diet (vehicle), LTT-rich diet (LTT), or calcium-rich diet (CaCO₃). Alveolar bone resorption (ABR), the number of osteoclasts, and the levels of tumor necrosis factor α (TNF-α), calcium, and vitamin D3 were evaluated.Results:The number of osteoclasts was reduced in LTT and CaCO₃ mice, which led to diminished OTM and infection-induced alveolar bone loss. In addition, LTT- and calcium-treated groups also presented decreased levels of TNF-α in periodontal tissues and increased levels of calcium in serum.Conclusions:These results indicate that the LTT supplement influences ABR, probably due to its calcium content, by affecting osteoclast function and local inflammatory response, thus modulating OTM and PD.