Figure 2 - uploaded by Toru Deguchi
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A drawing shows how the premolars were moved by the miniscrew-anchored mechanism. Histomorphometric analysis was performed in three different regions at the distal root of the premolars (upper, lower, apical: average region of interest in all three areas was 1.5 3 8.9 mm 2 ).
Source publication
Objective:
To investigate the relationship between root resorption (RR) and bone turnover in two different types of tooth movement in dogs.
Materials and methods:
A total of 16 dogs in two different groups were used. Tooth movement of dog premolars resulted from approximately 200 g of force. Histomorphometric analysis of premolar roots was asses...
Contexts in source publication
Context 1
... alveolar bone resorption in the compression zones seemed more rapid and extensive than in the normal rats. There is also a study that investigated the relationship between the bone turnover and RR after corticotomy. 10 However, there are few studies investigating the effect of RR relative to the change in the rate of surrounding alveolar bone turnover during tooth movement using histomorphometric analysis. Intrusion and tipping movements are known to be associated with RR. 5,6 With tipping, the periodontal ligament (PDL) peak stresses are known to be about three times greater than those with translation, and intrusion causes about four times more RR than extrusion. 5,6 Thus, investigating the incidence and the amount of RR in different types of tooth movement would be helpful in directing controlled tooth movement to avoid severe RR. Therefore, we hypothesized that there will be a reduced alveolar bone turnover adjacent to the root resorptive areas where high stress is associated with prolonged tooth movement. The study protocol was reviewed and approved by the Institutional Board of Animal Research Ethical Committee of Tohoku University. Sixteen 8-month-old beagle dogs (eight each for 4- and 12-week groups) were used. A total of 32 mandibular teeth were examined in each of four tooth movement groups (n 5 8); 4-week mainly intruded, 4-week mainly tipped, 12-week mainly intruded, and 12-week mainly tipped. The mainly tipped specimens were group A, and mainly intruded specimens were group B. The modifier ‘‘mainly’’ is used because the two groups were not exclusively tipped or intruded. The name of the group signifies the predominant type of tooth movement. Contralateral premolars were used as unloaded controls (n 5 8) (Figure 1). Impressions of the jaws for casts were taken before and after the tooth movement. Lidocaine (2% epinephrine) was injected into the mucoperiosteal flap. A crown with a hook was bonded to the second (group A) and third (group B) premolars. A 1-mm hole was drilled into the bone. Miniscrews (Titanium screw, Stryker Leibinger, Kal- amzoo, Mich; 1.0 mm in diameter and 5.0 mm in length) were inserted between the roots of the fourth premolars. Orthodontic force of 200 g was applied by the power chain attached from the miniscrew to the hook of the cast crown. Immediately before and after the tooth movement, radiographs were taken with the digital Schick x-ray computer program (CDR Schick Tec Inc, Long Island, NY). At 3 days and 10 days before humanely killing the animal, a sequence of two fluorochrome labels, calcein green (Sigma Chemical Co, St Louis, Mo) and tetracycline (Lederle Laborato- ries, American Cyanamid Co, Pearl River, NY), was administered by intravenous injection. After 4 or 12 weeks of experimental tooth movement, the dogs were euthanized. Specimens were fixed in 70% ethyl alcohol, and then dehydrated in an ascending series of ethyl alcohol baths, cleared in xylene, and infiltrated with methylmethacrylate for 20 hours. The tissues were placed in methylmethacrylate containing 3% dibutyl phthalate and 0.5% initiator (Perkodox 16, AKZO, Chicago, Ill). Before the specimen blocks were sectioned, they were all numbered and blinded. The Exakt cutting/grinding system (Exakt Medical Instruments, Oklahoma City, Okla) was used to finish the specimens after serial sectioning with a Leica 1600 Saw Microtome (Deer- field, Ill). Sections were polished to approximately 100 m m and mounted for bright field, fluorescent, and polarized light microscopy. Microradiographs were also produced using a Faxitron (Hewlett Packard, Beaverton, Ore). Since microradiographs enable us to distinguish the extent of mineralization, it was used to identify the area of root resorption and/or quality of surrounding bone. The area analyzed in this study was defined by a test line (dashed) bisecting the distal roots longitudi- nally and three solid lines perpendicular to the test line (Figure 2). The test line was defined as a perpendicular line to the line connected to the alveolar crest of the mesial and distal of the distal root. The distal alveolar surfaces, within 1.5 mm that directly faced the PDL in all three levels, were measured (Figure ...
Context 2
... alveolar bone resorption in the compression zones seemed more rapid and extensive than in the normal rats. There is also a study that investigated the relationship between the bone turnover and RR after corticotomy. 10 However, there are few studies investigating the effect of RR relative to the change in the rate of surrounding alveolar bone turnover during tooth movement using histomorphometric analysis. Intrusion and tipping movements are known to be associated with RR. 5,6 With tipping, the periodontal ligament (PDL) peak stresses are known to be about three times greater than those with translation, and intrusion causes about four times more RR than extrusion. 5,6 Thus, investigating the incidence and the amount of RR in different types of tooth movement would be helpful in directing controlled tooth movement to avoid severe RR. Therefore, we hypothesized that there will be a reduced alveolar bone turnover adjacent to the root resorptive areas where high stress is associated with prolonged tooth movement. The study protocol was reviewed and approved by the Institutional Board of Animal Research Ethical Committee of Tohoku University. Sixteen 8-month-old beagle dogs (eight each for 4- and 12-week groups) were used. A total of 32 mandibular teeth were examined in each of four tooth movement groups (n 5 8); 4-week mainly intruded, 4-week mainly tipped, 12-week mainly intruded, and 12-week mainly tipped. The mainly tipped specimens were group A, and mainly intruded specimens were group B. The modifier ‘‘mainly’’ is used because the two groups were not exclusively tipped or intruded. The name of the group signifies the predominant type of tooth movement. Contralateral premolars were used as unloaded controls (n 5 8) (Figure 1). Impressions of the jaws for casts were taken before and after the tooth movement. Lidocaine (2% epinephrine) was injected into the mucoperiosteal flap. A crown with a hook was bonded to the second (group A) and third (group B) premolars. A 1-mm hole was drilled into the bone. Miniscrews (Titanium screw, Stryker Leibinger, Kal- amzoo, Mich; 1.0 mm in diameter and 5.0 mm in length) were inserted between the roots of the fourth premolars. Orthodontic force of 200 g was applied by the power chain attached from the miniscrew to the hook of the cast crown. Immediately before and after the tooth movement, radiographs were taken with the digital Schick x-ray computer program (CDR Schick Tec Inc, Long Island, NY). At 3 days and 10 days before humanely killing the animal, a sequence of two fluorochrome labels, calcein green (Sigma Chemical Co, St Louis, Mo) and tetracycline (Lederle Laborato- ries, American Cyanamid Co, Pearl River, NY), was administered by intravenous injection. After 4 or 12 weeks of experimental tooth movement, the dogs were euthanized. Specimens were fixed in 70% ethyl alcohol, and then dehydrated in an ascending series of ethyl alcohol baths, cleared in xylene, and infiltrated with methylmethacrylate for 20 hours. The tissues were placed in methylmethacrylate containing 3% dibutyl phthalate and 0.5% initiator (Perkodox 16, AKZO, Chicago, Ill). Before the specimen blocks were sectioned, they were all numbered and blinded. The Exakt cutting/grinding system (Exakt Medical Instruments, Oklahoma City, Okla) was used to finish the specimens after serial sectioning with a Leica 1600 Saw Microtome (Deer- field, Ill). Sections were polished to approximately 100 m m and mounted for bright field, fluorescent, and polarized light microscopy. Microradiographs were also produced using a Faxitron (Hewlett Packard, Beaverton, Ore). Since microradiographs enable us to distinguish the extent of mineralization, it was used to identify the area of root resorption and/or quality of surrounding bone. The area analyzed in this study was defined by a test line (dashed) bisecting the distal roots longitudi- nally and three solid lines perpendicular to the test line (Figure 2). The test line was defined as a perpendicular line to the line connected to the alveolar crest of the mesial and distal of the distal root. The distal alveolar surfaces, within 1.5 mm that directly faced the PDL in all three levels, were measured (Figure ...
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Background/purpose
Orthodontic tooth movement is achieved by alveolar bone remodeling, and therefore the balance of bone resorption and formation is important. Receptor activator of nuclear factor-κB ligand (RANKL) plays a crucial role in bone resorption. We previously reported that tumor necrosis factor-α (TNF-α) is also important in bone resorpti...
Statement of the Problem: Root resorption (RR) after orthodontic tooth movement (OTM) is known as a multifactorial complication of orthodontic treatments. Hormonal deficiencies and their effect on bone turnover are reported to have influences on the rate of tooth movement and root resorption.
Purpose: This study was designed to evaluate the effect...
Citations
... 15,16 Root resorption (RR) is a serious complication that should be avoided during orthodontic treatment. This pathology depends on multiple factors, including: 1) factors specific to the patient, such as genetics (interleukin (IL)-1β polymorphism), 17 age and gender, 18 personal habits, 2,19 shape of the root, 10 systemic factors, 20 periodontal disease, [21][22][23] occlusal relationship, 24,25 dental morphology, 26 dental size, 27 traumatized teeth, 28 periapical infection, 29 and previous root resorption 15 ; and 2) factors related to orthodontic treatment, 30 such as inadequate biomechanics, 31 long duration of treatment, 32 type of orthodontic movements, 33 intensity of the forces, 34 range of movements, and type of orthodontic appliances. 35 The mandibular and maxillary incisors have been reported as the teeth most susceptible to RR due to orthodontic treatment 36 ; therefore, the orthodontist should consider determining factors for proper management during orthodontic treatment. ...
External apical root resorption (EARR) is a serious complication that should be avoided during orthodontic treatment; this pathology depends on multiple factors. Data from clinical studies should be assessed to determine the influence these factors have on the development of EARR. This systematic review aims to compare EARR produced by different factors (orthodontic systems, dental trauma, and dental vitality). The protocol was registered on the PROSPERO database. The search was performed on 5 databases. Accepted study designs included randomized controlled trials, nonrandomized clinical trials, and observational studies. Full-text articles from clinical studies of EARR associated with orthodontic treatment in English, Spanish, or Portuguese with no publication date restrictions were selected. Data from the studies, such as age, population, study groups, and outcome measures, were recorded. Multiple meta-analyses were performed with data from the included studies. Evidence suggests that EARR induced by orthodontic treatment is similar, regardless of the technique used. Evidence of the effect of previous dental trauma on EARR during orthodontic treatment is limited. There is less EARR associated with orthodontic treatment in endodontically treated teeth than in vital teeth. These conclusions should be considered with caution due to the low certainty of the evidence.
... Bone metabolism not only affects the acceleration of tooth movement but also modifies the periodontal tissue and therefore the extent of root resorption [15]. A low bone turnover rate is considered to be a predisposing factor for root resorption, and high bone turnover is associated with less root resorption [16]. Moreover, studies have shown that periodic vibration [17] and low-level laser therapy (LLLT) stimulation during orthodontic treatment can increase the rate of bone turnover and thus reduce the extent of root resorption [18]. ...
Root resorption during orthodontic tooth movement (OTM) is caused by an imbalance between the bone turnover rate and applied mechanical stress. The administration of 4-hexylresorcinol (4HR) increases the bone turnover rate and factors associated with bone formation. Thus, 4HR may show protective activity against root resorption during orthodontic tooth movement (OTM). A total of 40 rats (male: 20; female: 20) were included in this study, and the mandibular first molar was subjected to excessive orthodontic force. The experimental group (n = 20) received 12.8 mg/kg of 4HR every 2 weeks. The controls (n = 20) received a solvent without 4HR. Both groups had the same sex distribution. On Day 28 after the initiation of OTM, all the animals were sacrificed for micro-computed tomography analysis, Western blot analysis, and immunohistochemistry. The ratios of the root length and root volume to the total volume were significantly higher in the experimental group compared to those in the control group (p < 0.05). The expression levels of OPG, RANKL, alkaline phosphatase, and Runx2 in the experimental group according to Western blotting were significantly higher in the experimental group compared to those in the control group (p < 0.05). Their expression was mainly found in the periodontal ligament area. In conclusion, the administration of 4HR decreased the root resorption caused by OTM and increased the expression levels of OPG, RANKL, alkaline phosphatase, and Runx2.
... After the corticotomy, tissues were activated by increased osteoclastogenesis that resulted in decreased bone density. 21 Deguchi et al. 22 found that increased root resorption was related to decreased bone turnover. It has been assumed that increased bone turnover leads to less PDL hyalinization and root resorption in both LF and HF groups. ...
Objectives:
To investigate the effects of light and heavy forces with corticotomy on tooth movement rate, alveolar bone response, and root resorption in a rat model.
Materials and methods:
The right and left sides of 40 male Wistar rats were randomly assigned using the split-mouth design to two groups: light force with corticotomy (LF) and heavy force with corticotomy (HF). Tooth movement was performed on the maxillary first molars using a nickel-titanium closed-coil spring delivering either 10 g (light force) or 50 g (heavy force). Tooth movement and alveolar bone response were assessed by micro-computed tomography (micro-CT) at day 0 as the baseline and on days 7, 14, 21, and 28. Root resorption was examined by histomorphometric analysis at day 28.
Results:
Micro-CT analysis showed a significantly greater tooth movement in the HF group at days 7 and 14 but no difference in bone volume fraction at any of the observed periods. Histomorphometric analysis found no significant difference in root resorption between the LF and HF groups at day 28.
Conclusions:
Heavy force with corticotomy increased tooth movement at days 7 and 14 but did not show any difference in alveolar bone change or root resorption.
From early goals of having ideal dental occlusion and jaw relationships, modern treatment goals now involve a soft tissue paradigm in human dentistry. Orthodontic treatment should be biologically based for a harmonious occlusion, rather than cosmetic orientation of teeth. Malocclusions in young dogs and cats with deciduous dentitions, which are best termed deciduous malocclusions, are not unusual. The aims of orthodontic treatment are to provide a reasonably functional, esthetic, stable, and harmonious occlusion by altering the position or presence of the natural teeth. Interceptive orthodontics is generally considered to be the extraction or recontouring (crown reduction) of primary or permanent teeth that are contributing or will contribute to alignment problems of the permanent dentition. Removable orthodontic appliances are those that are designed to be easily and routinely removed, and then reinserted. Orthodontic wire is commonly used in a large variety of orthodontic appliances.
Introduction
A randomized split-mouth experiment was performed in dogs to determine the effects of bone grafting, together with corticotomies and buccal tooth movements, on dehiscence formation.
Methods
Bilateral full-thickness mucoperiosteal buccal flaps were raised, and corticotomies were performed with a piezosurgery unit adjacent to the maxillary second premolars in 7 dogs. The experimental (graft+) side received a demineralized freeze-dried allograph and a resorbable collagen membrane. The second premolars were expanded with archwires for 9 weeks, followed by 3 weeks of consolidation. Soft tissue measurements included probing depths, attachment loss, and recession. Tooth movements were monitored using intraoral, radiographic, and model measurements. Bone surrounding the second premolars was evaluated with microcomputed tomography. New bone formation was analyzed histologically using calcein and alizarin fluorescent labels, and hematoxylin and eosin stains.
Results
Postsurgical healing progressed normally with no signs of infection. The graft+ and control (graft−) second premolars underwent similar amounts of expansion (about 2.5 mm intraorally; about 1.7 mm radiographically) and tipping, with no statistically significant side differences. The soft tissue periodontium was not affected on either side. There were bony dehiscences on both the graft+ and graft− sides, with slightly but significantly (P = 0.038) more bone loss over the mesial root on the graft− side. Bone material density was significantly (P = 0.028) greater on the graft+ side. Buccal bone apposition was evident surrounding graft particles, and mineralized particulate graft material was present at the apical aspect of the roots on the graft+ side.
Conclusions
Bone grafting does not prevent dehiscence formation because only a limited amount of new bone is formed, primarily at the more apical aspects of the tooth's roots.
