Comparative study of changes in the airway dimensions following the treatment of Class II malocclusion patients with the twin-block and Seifi appliances.

BACKGROUND: Functional appliances are frequently used to stimulate mandibular growth in cases of Class II malocclusion with mandibular deficiency. Many studies have reported improved pharyngeal airway passage (PAP) dimensions following functional appliance therapy in children. OBJECTIVES: The present study aimed to assess changes in the airway dimensions following the treatment of Class II malocclusion patients with the twin-block and Seifi appliances. MATERIAL AND METHODS: Lateral cephalograms of 37 patients with Class II malocclusion and mandibular deficiency treated with the twin-block appliance (n = 20) or the Seifi appliance (n = 17) were assessed in this before-and-after study. The preoperative and postoperative lateral cephalograms were compared to determine changes in the airway dimensions at the level of the palatal plane (PP), the occlusal plane (OP) and the 2nd-4th cervical vertebrae (C2-C4) in the 2 groups. The results were analyzed with the t test and the one-way analysis of covariance (ANCOVA). RESULTS: After treatment, significant changes occurred in the point A-nasion-point B (ANB) and sellanasion-point B (SNB) skeletal cephalometric indices in the twin-block appliance group, and in ANB, SNB and incisor-mandibular plane angle (IMPA) in the Seifi appliance group. The airway dimensions at the level of PP, OP and the 3rd cervical vertebra (C3) significantly increased postoperatively as compared to the baseline in the twin-block appliance group (p < 0.05). The increases in the airway dimensions at the level of PP and C3 in the twin-block appliance group were significantly greater than in the Seifi appliance group (p < 0.05). CONCLUSIONS: The treatment of Class II Division I malocclusion with the twin-block appliance significantly increased the airway dimensions at the level of PP, OP and C3, whereas the Seifi appliance did not cause any significant changes in the airway dimensions.

Evaluation of shear bond strength and enamel remineralizing effect of experimental orthodontic composite containing nano-hydroxyapatite: An in vitro study.

OBJECTIVE: The purpose of this study was to prepare an orthodontic composite containing hydroxyapatite nanoparticles to prevent demineralization and create a suitable environment for mineral deposition around orthodontic brackets, and to investigate the mechanical and remineralizing properties of the experimental adhesive composite. METHODS: Experimental orthodontic composite were formulated using varying percentages of nano-hydroxyapatite particles. Assessments were based on four groups: a control group (3M™ Transbond™ XT) and experimental composites containing 2% (HA2), 5% (HA5) and 10% (HA10) hydroxyapatite. Vickers Microhardness test was performed to investigate the remineralizing effect in 3 stages: initial stage, after demineralization and after 4 weeks of exposure to artificial saliva. Scanning electron microscopy with energy dispersive X-ray spectroscopy analyser (SEM/EDAX) was used to evaluate hydroxyapatite precipitation and elemental composition of enamel surface. Shear Bond Strength tests were carried out using a universal testing machine and the debonding pattern was assessed using Adhesive Remnant Index (ARI). RESULTS: All groups showed clinically acceptable SBS values. The highest SBS was achieved in the HA2 group, followed by Transbond™ XT, HA5 and HA10. There was no significant difference in the ARI scores. In terms of microhardness properties, HA5 and HA10 demonstrated a significant increase after 4 weeks. The results of SEM analysis showed the precipitation of hydroxyapatite crystals and EDAX analysis indicated the increase of calcium and phosphate ion peaks compared to the demineralized sample. The data were analysed using one-way ANOVA and Tukey's Post-hoc test. CONCLUSIONS: Addition of hydroxyapatite nanoparticles to orthodontic composite can increase the mineral content and microhardness of the adjacent enamel. However, increasing the amount of nanoparticles reduces shear bond strength in a decreasing trend. The above-mentioned findings showed that incremental increase of nanoparticles of HA can be incorporated in composite to a certain extent and limitations are determined by mechanical properties (SBS) required for bracket bonding.

Comparison of the failure rate, bonding time and ARI score of two orthodontic bonding systems: Self-Etch Primer and Conventional Etching Primer: A systematic review and meta-analysis.

OBJECTIVE: This study aimed to evaluate the failure incidence of brackets with at least six months follow-up between self-etch primer and conventional etch/primer, as well as to investigate the clinical duration of the bonding process and the amount of adhesive remnant index (ARI). METHODS: Electronic search was conducted in databases including PubMed, Scopus, Web of Science, ProQuest, ClinicalTrials.gov, and ICTRP (International Clinical Trials Registry Platform). The electronic search targeted only randomized clinical trials and was limited from January 2000 to June 2021. Delphi list is used to evaluate the risk of bias and Stata Version14.2 software was used. This systematic review was conducted according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and recorded on the Ethics Committee of Research Institute of Dental Sciences, SBMU (IR.SBMU.DRC.REC.1398.240). RESULTS: Out of 2288 extracted studies, 30 of them entered the full-text evaluation process. According to the inclusion criteria, 15 studies entered this systematic review. Containing 607 participants and 10,563 brackets/teeth. All the included studies were of randomized clinical trials (RCT) design with either parallel or split-mouth design. Comparing the two groups, the risk difference effect (RD)=0.007 CI 95% (-0.004,0.018) indicated a neglectable difference in the risk of bracket failure during treatment between the two groups. The index I2=53.9% indicated moderate heterogeneity in the results. Furthermore, the P-value=0.007 indicated statistical insignificance between the two interventions in terms of failure rate. The clinical duration of bonding time analysis were equal to SMD _Cohen=-2.67 CI95% (-3.49, -1.85), which indicated a statistically significant reduction in clinical process time, using the self-etch primer. Data synthesis for adhesive remnant index could not be conducted due to heterogeneity among included studies. CONCLUSIONS: There was no difference between the self-etch primer and conventional etch/primer in bracket debonding at a medium level of evidence, However, there was statistically significant reduction in clinical bonding time using self-etch primer.

Evaluation of caries risk reduction following preventive programs in orthodontic patients, using Cariogram computer model: A quasi-experimental trial.

OBJECTIVE: This study evaluated the effectiveness of preventive strategies on caries risk reduction in patients undergoing orthodontic treatment, using the Cariogram program. METHODS: In this quasi-experimental study, samples were selected using a convenience quota sampling technique, in a public dental school. At first, caries risk profile was determined for each subject using the Cariogram before brackets bonding. The sample size consisted of 36 patients. The intervention group (n = 18) received preventive programs, and the control group (n = 18) was trained based on the routine oral health education by means of pamphlets. Then, Cariogram parameters were calculated for patients in both groups after six months. RESULTS: The age range of participants was from 12 to 29 years. The mean percentage of the "Actual chance of avoiding new cavities" section in the intervention group increased from 45.72 ± 21.64 to 62.50 ± 17.64. However, the mean percentage of other parameters - such as "Diet", "Bacteria" and "Susceptibility" - decreased after six months (p< 0.001). Besides, the differences in the mean percentage between intervention and control group at the end of the study period (T1) related to the Cariogram parameters were statistically significant (p< 0.001). Accordingly, the mean percentage of 'Actual chance of avoiding new cavities'' parameter in the intervention group (62.50) was statistically higher than in the control group (42.44) (p< 0.001). CONCLUSION: Implementing different preventive approaches is able to reduce the caries risk in patients undergoing fixed orthodontic treatment, which can be clearly demonstrated using Cariogram program.

Evaluation of caries risk reduction following preventive programs in orthodontic patients, using Cariogram computer model: A quasi-experimental trial

ABSTRACT Objective: This study evaluated the effectiveness of preventive strategies on caries risk reduction in patients undergoing orthodontic treatment, using the Cariogram program. Methods: In this quasi-experimental study, samples were selected using a convenience quota sampling technique, in a public dental school. At first, caries risk profile was determined for each subject using the Cariogram before brackets bonding. The sample size consisted of 36 patients. The intervention group (n = 18) received preventive programs, and the control group (n = 18) was trained based on the routine oral health education by means of pamphlets. Then, Cariogram parameters were calculated for patients in both groups after six months. Results: The age range of participants was from 12 to 29 years. The mean percentage of the "Actual chance of avoiding new cavities" section in the intervention group increased from 45.72 ± 21.64 to 62.50 ± 17.64. However, the mean percentage of other parameters - such as "Diet", "Bacteria" and "Susceptibility" - decreased after six months (p< 0.001). Besides, the differences in the mean percentage between intervention and control group at the end of the study period (T1) related to the Cariogram parameters were statistically significant (p< 0.001). Accordingly, the mean percentage of 'Actual chance of avoiding new cavities'' parameter in the intervention group (62.50) was statistically higher than in the control group (42.44) (p< 0.001). Conclusion: Implementing different preventive approaches is able to reduce the caries risk in patients undergoing fixed orthodontic treatment, which can be clearly demonstrated using Cariogram program.

RESUMO Objetivo: O presente estudo usou o software Cariogram para avaliar a eficácia de estratégias preventivas para redução do risco de cáries em pacientes sob tratamento ortodôntico. Métodos: Nesse estudo quase-experimental, as amostras foram selecionadas por meio de uma técnica de amostragem por cota de conveniência, em uma faculdade pública de Odontologia. Inicialmente, o perfil de risco de cárie foi determinado para cada indivíduo usando o Cariogram antes da colagem dos braquetes. A amostra consistiu de 36 pacientes: o grupo experimental (n = 18) recebeu programas preventivos, e o grupo controle (n = 18) recebeu orientações sobre a saúde bucal por meio de folhetos. Após seis meses, os parâmetros obtidos por meio do Cariogram foram calculados novamente para os pacientes de ambos os grupos. Resultados: A faixa etária dos participantes foi de 12 a 29 anos. A porcentagem média da seção "Probabilidade real de prevenir novas cáries" no grupo experimental aumentou de 45,72 ± 21,64 para 62,50 ± 17,64. Por outro lado, a porcentagem média de outros parâmetros - como "Dieta", "Bactérias" e "Suscetibilidade" - diminuiu após seis meses (p< 0,001). Além disso, as diferenças nas porcentagens médias entre o grupo experimental e o grupo controle ao fim do estudo (T1), relacionadas aos parâmetros do Cariogram, foram estatisticamente significativas (p< 0,001). Assim, a porcentagem média do parâmetro "Probabilidade real de prevenir novas cáries" no grupo experimental (62,50) foi estatisticamente maior do que no grupo controle (42,44) (p< 0,001). Conclusão: A implementação de diferentes abordagens preventivas pode reduzir o risco de cárie em pacientes sob tratamento ortodôntico com aparelhos fixos, o que pode ser observado claramente por meio do software Cariogram.

Association between Lateral Cephalometric Changes in X-Y Coordinate System and Profile Changes among Skeletal Class III Patients after Orthognathic Surgery.

BACKGROUND: Since aesthetic issues are the most important causes of referring skeletal class III patients to surgeons, investigating the impact of orthognathic surgeries on improving patient profiles increases the quality of treatment and quality of life. METHODS: In a retrospective observational-analytical study, 25 patients older than 18 years with class III skeletal malocclusion who had gone under both orthodontic and double-jaw orthognathic treatment were enrolled. Cephalometric imaging interval was before and at least 6 months after surgery. By defining a number of points and coordinate axes (X-Y), a criterion for comparing hard and soft tissue changes was obtained. These measurements were coordinated, linear and angular. The quantitative data were compared with data obtained using the Likert Scale Questionnaire by means of electronic "Google Forms" that was completed by orthodontists (n=5) and maxillofacial surgeons (n=5) to rank improvement in post-surgical profiles for both cephalometry and photography from poor to pleasant. Spearman Correlation Analysis was conducted between the quantitative and qualitative data. RESULTS: Vertical changes of point B and horizontal changes of point PNS showed correlation with improvement of patient profile. Changes in N-Pog line (R=-0.4), mandibular plane angle (R=-0.4) and nasolabial angle (NLA) (R=0.38) were significantly correlated with improvement of profiles. CONCLUSION: In orthognathic double-jaw surgery on patients with skeletal Class III, forward movement of maxilla, upward positioning of mandible (decreasing anterior facial height), decreasing mandibular plane angle and increasing nasolabial angle would result in a better profile.

Dentoskeletal Stability in Conventional Orthognathic Surgery, Presurgical Orthodontic Treatment and Surgery-First Approach in Class-III Patients.

For many years, the conventional approach to orthognathic surgery which was orthodontic treatment prior to orthognathic surgery has been the accepted method of treatment for skeletal class III malocclusion patients. This review compared the dentoskeletal stability of treatment results between conventional orthognathic surgery methods with presurgical orthodontic treatment and surgery-first approach in skeletal class III patients. The study protocol was based on Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement for systematic review and meta-analysis. Electronic and manual searches for literature since 2011 were conducted. PubMed and Medline databases were accessed. Data extraction and analysis were performed by two independent individuals. Seven studies out of hundred-fourteen articles met the inclusion criteria and were selected for qualitative analysis. The included studies were 494 patients with skeletal class-III malocclusion. Stability of treatment was compared between surgery-first approach and conventionally treated patients. The statistical analysis confirmed that surgery-first approach did not show more stability compared with presurgical orthodontics. The surgery-first approach shortened the overall treatment duration. However, more skeletal stability in conventional treatment was assessed. Both surgery-first approach and conventional treatment with presurgical orthodontics resulted in favorable skeletal changes in class-III malocclusion patients. Moreover, these findings should be discussed further due to the variety of study designs, outcomes and biases. Current evidence in this field still needs to be expanded. The authors wish to see more well-designed randomized controlled trials with long-term follow ups to confirm the results.

Innovative evaluation of local injective gel of curcumin on the orthodontic tooth movement in rats.

BACKGROUND: Curcumin is the most active compound in turmeric. It can suppress the nuclear factor kappa-light-chain-enhancer of activated B cells pathway and prevent the osteoclastogenesis procedure. This study aimed to be the first to evaluate the effect of curcumin on the rate of orthodontic tooth movement (OTM). MATERIALS AND METHODS: Forty rats were used as follows in each group: (1) negative control: Did not receive any appliance or injection; (2) positive control: received 0.03 cc normal saline and appliance; (3) gelatin plus curcumin (G): Received 0.03 cc hydrogel and appliance; and (4) chitosan plus curcumin (Ch): Received 0.03 cc hydrogel and appliance. They were anesthetized and closed nickel-titanium coil springs were installed between the first molars and central incisors unilaterally as the orthodontic appliance. After 21 days, the rats were decapitated, and the distance between the first and second molars was measured by a leaf gauge. Howship's lacunae, blood vessels, osteoclast-like cells, and root resorption lacunae were evaluated in the histological analysis. Data were analyzed by one-way ANOVA, Tukey's test, and t-test (P < 0.05 consider significant). RESULTS: No significant difference was found in OTM between groups delivered orthodontic forces. Curcumin inhibited root and bone resorption, osteoclastic recruitment, and angiogenesis significantly. CONCLUSION: Curcumin had no significant inhibitory effect on OTM. While it had a significant role on decreasing bone or root resorption (P > 0.05).

Laser Surgery of Soft Tissue in Orthodontics: Review of the Clinical Trials.

Introduction: Recently, a wide variety of procedures have been done by laser application in orthodontics. Apart from the mentioned range of various treatments, laser has become a tool for many soft tissue surgeries as an alternative to conventional scalpel-based technique during orthodontic treatments in the management of soft tissue. Due to scarce information in the latter subject, this study was designed in order to include clinical trials that included soft tissue ablation by laser in orthodontics. Methods: Literature was searched based on PubMed and Google Scholar databases in 5 years (2010-2015) with English language restriction and clinical trial design. Studies that performed soft tissue application of laser during orthodontic treatment were extracted by the authors. Results: Only eight studies met the inclusion criteria. No significant difference was found between laser ablation and conventional scalpel technique in the matter of treatment outcome. However, few issues remained to clarify the differences in the mentioned procedures. Conclusion: Laser performance can be recommended in case of preceding less bleeding and discomfort during surgical procedure. There are still quandaries among clinical application of scalpel-based surgery in aesthetic region with bracket-bonded teeth. Precaution and knowledge regarding the characteristics of laser beam such as wavelength, frequency, power and timing is extremely needed.

Comparative effectiveness of Low Level Laser therapy and Transcutaneous Electric Nerve Stimulation on Temporomandibular Joint Disorders.

Introduction: Temporomandibular joint disorders (TMDs) are the most common source of pain on the face. There are multiple etiologies, and several types of treatment have been reported. The use of non-invasive and reversible therapies in the treatment of such problems is recommended. The present study evaluated the effect of low-level laser (LLL) therapy and transcutaneous electric nerve stimulation (TENS) on TMDs. Methods: In this single-blind study, 40 patients with temporomandibular disorders were randomly divided into four groups: TENS (TENSTem dental), LLL (diode 810 nm CW), shamTENS, and sham-LLL. All subjects were examined and data on pain and tenderness in the temporomandibular joint (TMJ) and masticatory muscles (using the visual analogue scale) and mouth-opening (distance between incisal edges before feeling pain; mm) were collected before baseline (T1), after each session (T2-T5) and one month after the end of the sessions (T6)), and analyzed using repeated measure analysis of variance (ANOVA) and Bonferroni statistical tests. A P value < 0.05 was considered significant. Results: The decrease in pain (P=0.000), tenderness (P=0.000) and increase in mouth-opening ability (P=0.002) was greater in the TENS and LLL groups than in the placebo groups. At the one-month follow-up, significant decrease in pain and tenderness was recorded in the TENS and LLL groups (P=0.000). There was no significant differences between TENS and LLL and the placebo groups for maximum mouth-opening at the end of the study (P=0.692). Conclusion: Using TENS or LLL therapy can improve TMD symptoms at least for the short term. Although the effects of the placebo played a role in improving symptoms, their effects were less important.

Analysis of Transforming Growth Factor- ß1 Expression in Resorptive Lacunae following Orthodontic Tooth Movement in An Animal Model.

OBJECTIVE: Root resorption is a complication of orthodontic treatment and till date, there is a dearth of information regarding this issue. The aim of this study was to determine whether the expression of transforming growth factor-ß1 (TGF-ß1, an inflammatory cytokine) is related to orthodontic force. Moreover, if associated, the expression level may be helpful in differential diagnosis, control and ultimate treatment of the disease. MATERIALS AND METHODS: In this experimental study, a total of 24 eight-week-old male Wistar rats were selected randomly. On day 0, an orthodontic appliance, which consisted of a closed coil spring, was ligated to the upper right first molar and incisor. The upper left first molar in these animals was not placed under orthodontic force, thus serving as the control group. On day 21, after anesthesia, the animals were sacrificed. The rats were then divided into two equal groups where the first group was subjected to histological evaluation and the second group to reverse transcriptase-polymerase chain reaction (RT-PCR). Orthodontic tooth movement was measured in both groups to determine the influence of the applied force. RESULTS: Statistical analysis of data showed a significant root resorption between the experimental group and control group (P<0.05), however, there was no significant difference in the expression level of the inflammatory cytokine, TGF-ß1. CONCLUSION: Based on the findings of this study, we suggest that there is a direct relationship between orthodontic force and orthodontic induced inflammatory root resorption. In addition, no relationship is likely to exist between root resorption and TGF-ß1 expression in the resorptive lacunae.

Ultraviolet-induced surface grafting of octafluoropentyl methacrylate on polyether ether ketone for inducing antibiofilm properties.

Since octafluoropentyl methacrylate is an antifouling polymer, surface modification of polyether ether ketone with octafluoropentyl methacrylate is a practical approach to obtaining anti-biofilm biocompatible devices. In the current study, the surface treatment of polyether ether ketone by the use of ultraviolet irradiation, so as to graft (octafluoropentyl methacrylate) polymer chains, was initially implemented and then investigated. The Fourier-transform infrared and nuclear magnetic resonance spectra corroborated the appearance of new signals associated with the fluoroacrylate group. Thermogravimetric curves indicated enhanced asymmetry in the polymer structure due to the introduction of the said new groups. Measuring the peak area in differential scanning calorimetry experiments also showed additional bond formation. Static water contact angle measurements indicated a change in wettability to the more hydrophobic surface. The polyether ether ketone-octafluoropentyl methacrylate surface greatly reduced the protein adsorption. This efficient method can modulate and tune the surface properties of polyether ether ketone according to specific applications.

Effect of local injection of Zolena, zoledronic acid made in Iran, on orthodontic tooth movement and root and bone resorption in rats.

Background. Anchorage control is an essential part of orthodontic treatment planning, especially in adult patients who demand a more convenient treatment. Zoledronic acid (ZA) is an effective choice to address this problem. It is the most potent member of the bisphosphonates family that has an inhibitory effect on bone resorption by suppressing osteoclast function. Therefore, ZA might be a good option for orthodontic anchorage control. The current study evaluated the effect of local administration of Zolena (ZA made in Iran) on orthodontic tooth movement (OTM) and root and bone resorption. Methods. The experimental group consisted of 30 rats in 3 subgroups (n=10). Anesthesia was induced, and one closed NiTi coil spring was installed between the first molar and central incisor unilaterally, except for the negative control group. The positive control group received vestibular injection of 0.01 mL of saline next to the maxillary first molar, and 0.01 mL of the solution was injected at the same site in the ZA group. After 21 days, the rats were sacrificed and the distance between the first and second molars was measured with a leaf gauge. Histological analysis was conducted by a blind pathologist for the number of Howship's lacunae, blood vessels, osteoclast-like cells and root resorption lacunae. Data were analyzed with ANOVA, Tukey test and t-test. Results. There were no significant differences in OTM between the force-applied groups. ZA significantly inhibited bone/root resorption and angiogenesis compared to the positive control group. Conclusion. Zolena did not decrease OTM but significantly inhibited bone and root resorption. Zolena might be less potent than its foreign counterparts.

The Effect of An Angiogenic Cytokine on Orthodontically Induced Inflammatory Root Resorption.

OBJECTIVE: Orthodontically induced inflammatory root resorption (OIIRR) is an undesirable sequel of tooth movement after sterile necrosis that takes place in periodontal ligament due to blockage of blood vessels following exertion of orthodontic force. This study sought to assess the effect of an angiogenic cytokine on OIIRR in rat model. MATERIALS AND METHODS: In this experimental animal study, 50 rats were randomly divided into 5 groups of 10 each: E10, E100 and E1000 receiving an injection of 10, 100 and 1000 ng of basic fibroblast growth factor (bFGF), respectively, positive control group (CP) receiving an orthodontic appliance and injection of phosphate buffered saline (PBS) and the negative control group (CN) receiving only the anesthetic agent. A nickel titanium coil spring was placed between the first molar and the incisor on the right side of maxilla. Twenty-one days later, the rats were sacrificed. Histopathological sections were made to assess the number and area of resorption lacunae, number of blood vessels, osteoclasts and Howship's lacunae. Data were statistically analyzed using ANOVA and Tukey's honest significant difference (HSD) test. RESULTS: Number of resorption lacunae and area of resorption lacunae in E1000 (0.97 ± 0.80 and 1. 27 ± 0.01×10(-3), respectively) were significantly lower than in CP (4.17 ± 0.90 and 2.77 ± 0.01×10-3, respectively, P=0.000). Number of blood vessels, osteoclasts and Howship's lacunae were significantly higher in E1000 compared to CP (P<0.05). CONCLUSION: Tooth movement as the outcome of bone remodeling is concomitant with the formation of sterile necrosis in the periodontal ligament following blocked blood supply. Thus, bFGF can significantly decrease the risk of root resorption by providing more oxygen and angiogenesis.

Evaluation of primary stability of innovated orthodontic miniscrew system (STS): An ex-vivo study.

BACKGROUND: Stability is determined as one of the requirements in use of Temporary Anchorage Devices (TAD) in orthodontics. Miniscrew has been a widely used Bone Anchor. Compared with mini-implant that necessitates osseointegration; mechanical retention is a determining factor for primary stability of miniscrew. Studies investigated various ways to increase primary stability. The aim of this study is to introduce a new configuration of miniscrew system which is believed to obtain more primary stability. MATERIAL AND METHODS: Freshly ovine mandibles were cut in blocks. Twenty-seven miniscrews (diameter 1.6 × 8 mm; G2, Dual Top Anchor System, Jeil Medical, Seoul, Korea) were inserted in the blocks and divided in 2 experimental groups: single miniscrew and the innovated design "Seifi Twin Screw (STS)". Primary stability was evaluated by Periotest "M"® device. RESULTS: Independent t-test showed a significant difference between 2 experimental groups in periotest evaluation (p< 0.05). STS demonstrated higher primary stability due to its mechanical configuration and design. CONCLUSIONS: The STS provides higher primary stability and was found to be effective in increased success rate of miniscrew systems from the standpoint of primary stability. KEY WORDS: Anchorage procedures, anchorage techniques, orthodontic anchorage procedures, miniscrews, temporary anchorage device.

The Effect of Ovariectomy and Orchiectomy on Orthodontic Tooth Movement and Root Resorption in Wistar Rats.

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 of female and male steroid sex hormones on tooth movement and root resorption. MATERIALS AND METHOD: Orthodontic appliances were placed on the right maxillary first molars of 10 ovariectomized female and 10 orchiectomized male Wistar rats as experimental groups and 10 female and 10 male healthy Wistar rats as control groups. NiTi closed-coil springs (9mm, Medium, 011"×.030", Ortho Technology(®); Tampa, Florida) were placed between the right incisors and the first right maxillary molars to induce tipping movement in the first molars with the application of a 60g force. After 21 days, the rats were sacrificed and tooth movement was measured by using a digital caliper (Guanglu, China). Orthodontic induced root resorption (OIRR) was assessed by histomorphometric analysis after hematoxylin and eosin staining of sections of the mesial root. RESULTS: The rate of tooth movement was significantly higher in all female rats, with the root resorption being lower in the experimental group. The rate of tooth movement in experimental male rats was significantly higher than the control group (p= 0.001) and the rate of root resorption was significantly lower in the experimental group (p= 0.001). CONCLUSION: It seems that alterations in plasma levels of estrogen, progesterone, and testosterone hormones can influence the rate of OTM and RR. The acceleration in tooth movement increased OTM and decreased RR.

The Effect of Thyroid Hormone, Prostaglandin E2, and Calcium Gluconate on Orthodontic Tooth Movement and Root Resorption in Rats.

STATEMENT OF THE PROBLEM: A major objective of investigators is to clarify the role of metabolites in achievement of maximum tooth movement with minimal root damage during orthodontic tooth movement (OTM). PURPOSE: The aim of this study was to determine the effect of administration of thyroid hormone, prostaglandin E2, and calcium on orthodontic tooth movement and root resorption in rats. MATERIALS AND METHOD: Sixty four male Wistar rats were randomly divided into 8 groups of eight rats each: 1- 20µg/kg thyroxine was injected in traperitoneally after installation of the orthodontic appliance.  2- 0.1 ml of 1 mg/ml prostaglandin E2 was injected submucosally.  3- 10% (200 mg/kg) calcium gluconate was injected.  4- Prostaglandin E2 was injected submucosally and 10% calcium was injected intraperitoneally.  5- Thyroxine was injected intraperitoneally and prostaglandin E2 was injected submucosally.  6- 20µg/kg thyroxine with calcium was injected. 7- Prostaglandin E2 was injected submucosally with calcium and thyroxine.  8- Distilled water was used in control group. The orthodontic appliances comprised of a NiTi closed coil were posteriorly connected to the right first molar and anteriorly to the upper right incisor. OTM was measured with a feeler gauge. The mid-mesial root of the first molar and the adjacent tissues were histologically evaluated. The Data were analyzed by one-way ANOVA and Student-Newman-Keuls test. RESULTS: The highest mean OTM was observed in the thyroxine and prostaglandin E2 group (Mean±SD = 0.7375±0.1359 mm) that was significantly different (p< 0.05). A significant difference (p< 0.05) in root resorption was observed between the prostaglandin E2 (0.0192±0.0198 mm(2)) and the other groups. CONCLUSION: It seems that the combination of thyroxine and prostaglandin E2, with a synergistic effect, would decrease the root resorption and increase the rate of orthodontic tooth movement in rats.

Effect of nanocrystalline hydroxyapatite socket preservation on orthodontically induced inflammatory root resorption.

OBJECTIVE: Orthodontically induced inflammatory root resorption (OIIRR) is considered to be an important sequel associated with orthodontic tooth movement (OTM). OTM after Socket preservation enhances the periodontal condition before orthodontic space closure. The purpose of this study is to investigate the histologic effects of NanoBone®, a new highly nonsintered porous nano-crystalline hydroxyapatite bone on root resorption following OTM. MATERIALS AND METHODS: This experimental study was conducted on four male dogs. In each dog, four defects were created at the mesial aspects of the maxillary and mandibular first premolars. The defects were filled with NanoBone®. We used the NiTi closed coil for mesial movement of the first premolar tooth. When the experimental teeth moved approximately halfway into the defects, after two months, the animals were sacrificed and we harvested the area of interest. The first premolar root and adjacent tissues were histologically evaluated. The three-way ANOVA statistical test was used for comparison. RESULTS: The mean root resorption in the synthetic bone substitute group was 22.87 ± 11.25×10(-4)mm(2) in the maxilla and 21.41 ± 11.25×10(-4)mm(2) in the mandible. Statistically, there was no significant difference compared to the control group (p>0.05). CONCLUSION: The use of a substitution graft in the nano particle has some positive effects in accessing healthy periodontal tissue following orthodontic procedures without significant influence on root resorption (RR). Histological evaluation in the present study showed osteoblastic activity and remodeling environment of nanoparticles in NanoBone®.

Tooth movement alterations by different low level laser protocols: a literature review.

Low-Level Laser Therapy (LLLT) provides several benefits for patients receiving orthodontic treatment. According to some literatures, Orthodontic Tooth Movement (OTM) can be enhanced but some investigators have reported contradictory results. This article reviews the literature regarding the different aspects of the use of LLLT on OTM and its alterations. The general data regarding the study design, sample size, wavelength (nm), power (mW), and duration were extracted and recorded independently. Electronic databases of PubMed and ScienceDirect from January 2009 to August 2014 were searched. Also Google Scholar and grey literature was searched for relevant references. Some investigators found that the amount of tooth movement in the Low-Energy Laser Irradiation (LELI) group was significantly greater than in the nonirradiation group by the end of the experimental period. Low-level laser irradiation accelerates the bone remodeling process by stimulating osteoblastic and osteoclastic cell proliferation and function during orthodontic tooth movement. But some researchers have reported that no statistical differences in the mean rate of tooth movement were noted between low energy and high energy experimental sides and their controls. Some evidence shows that low-level laser irradiation accelerates the bone remodeling process and some evidence shows that LLLT has not effect on OTM. In some investigations no statistical differences in the mean rate of tooth movement can be seen between low energy and high energy experimental sides and their controls. It has been shown by authors that laser irradiation can reduce the amount of OTM and a clinical usage for the inhibitory role of low level laser irradiation is enforcing the anchorage unit.

Effects of low-level laser therapy on orthodontic tooth movement and root resorption after artificial socket preservation.

BACKGROUND: Low- level laser therapy has been used to stimulate the orthodontic tooth movements (OTM) previously. Furthermore, in the orthodontic treatments accompanying tooth extractions, the adjacent teeth move towards the extraction sites and close the space in some cases. Then, the adjacent tooth movements must be prevented in the treatments requiring space. Laser stimulates and at some doses decelerates tooth movement; it also improves healing process and enhances osteogenesis. Hence, it can prevent movement by osteogenesis adjacent to the tooth. The present study investigated the effects of low-level laser therapy on the OTM and root resorption following artificial socket preservation. MATERIALS AND METHODS: In this experimental animal trial, 16 male albino rabbits were selected with similar characteristics and randomly divided in two groups. Under general anesthesia, an artificial socket, 8 mm in height, was created in the mesial aspect of the first premolars of the rabbits and filled with demineralized freeze dried bone allograft (DFDBA). The first premolars were connected to the incisors using nickel titanium coil springs. In experimental group, gallium-aluminum-arsenide (GaAlAs) laser was irritated mesial to first premolar where artificial socket was created continuously (808 nm). The cycle was 10 days irritation, 14 days rest, 10 days irritation, 14 days rest (Biostimulation mode). Control group was not laser irradiated. All animals were sacrificed after 48 days and the distance between the distal aspect of the first premolars, and the mesial surface of the second premolars was measured with leaf gauge. The specimens underwent histological assessments. Integrity of root and its resorption was observed under microscope calibration. The size of resorption lacunae was calculated in mm(2). Normality of data was proved according to Kolmogorov-Smirnov analysis, and Student's t-test was done. P value less than 0.05 was considered as significant. RESULTS: The mean OTM were 5.68 ± 1.21 mm in the control group and 6.0 ± 0.99 mm in the laser irradiated teeth with no statistically significant differences(P > 0.75). The mean root resorption was 1.61 ± 0.43 mm(2) and 0.18 ± 0.07 mm(2) in the control and experimental groups respectively being significantly lower in the laser irradiated teeth (P < 0.0001). CONCLUSION: The findings of the present study show that GaAlAs irradiation together with the application of DFDBA led to limited amount of the stimulated OTM. The laser beam irradiation in combination with alloplastic materials used for socket preservation could reduce the degree of root resorption significantly.