Oral Hygiene in the Presence of Orthodontic Therapy

Orthodontic treatment offers great advantages in improving facial and smile aesthetics, self-confidence and the function of the stomatognathic apparatus. The pursuit of these advantages makes use of orthodontic appliances that could be fixed or removable. However, it’s worth stating that these appliances interfere with tooth brushing, making it more difficult to brush teeth effectively. Orthodontics appliances therefore promote the accumulation of dental plaque, which results in both quantitative and qualitative changes in the oral microbiota, hence, exposing patients to several adverse effects such as White spot lesions, dental caries, periodontal pathologies and halitosis. For this reason, oral assessment of patients before, during and after treatment is necessary as well as oral hygiene instructions and motivation. Orthodontists therefore, should educate patients on oral and periodontal hygiene in order to control dental and periodontal complications. Prescriptions of plaque control materials adapted to each patient are done in order to optimize the final result and minimize unwanted complications.

Knowledge and Attitudes of Knust Pre-Clinical Dental Students towards Orthodontic Treatment

Background: Orthodontics is a dental specialty focusing on correcting dental irregularities and malocclusion. Knowledge and attitudes towards orthodontic treatment are crucial for promoting oral health and overall well-being. Education and awareness play a vital role in ensuring optimal treatment outcomes and improving quality of life. Aim: This study aims to determine the knowledge and attitudes of Kwame Nkrumah University of Science and Technology (KNUST) pre-clinical dentistry students concerning orthodontic therapy. Methodology: This research is a quantitative descriptive cross-sectional study. The research used a non-random convenience sampling method to form the desired sample. For data collection, an interview-administered questionnaire was used over one month. The study set its sights on pre-clinical dental students in KNUST. A total of 150 questionnaires were printed to meet the sample size. Results: The results of the research showed that the knowledge level of KNUST pre-clinical students on orthodontic treatment and its nuances is quite limited. They however had a fair level of knowledge on the disease or ailment that orthodontic treatments solved (especially malocclusion). Their interest in orthodontic treatments on the other hand was quite significant, with a large number having interest in it. Conclusion: To conclude, KNUST pre-clinical students in Ghana although having a limited level of knowledge on orthodontic treatments have a keen interest in undergoing them regardless of the discomforts or the length of time.

Effect of different interventions on orthodontic tooth movement acceleration:A network meta-analysis

Objective: To explore the effectiveness of various interventions in accelerating tooth movement, a systematic review and net-work meta analysis were used to draw a conclusion. Methods: MEDLINE, EMBASE, Willey Library, EBSCO, Web of Science Databases, and Cochrane Central Register of Controlled Trials databases to identify relevant studies. ADDIS 1.16.6 and Stata 16.0 software were used for NMA. Results: Five thousand five hundred and forty-two articles were searched out. After screening by two independent investigators, forty-seven randomized controlled trials, 1 390 participants, were included in this network meta-analysis. A total of 11 interventions involving Piezocision (Piezo), Photobiomodulation therapy (PBMT), Plate- let-rich plasma(PRP), Electromagnetic field(EF), Low intensity laser therapy(LLLT), Low intensity pulsed ultrasound(LI-PUS), Low-frequency vibrations(LFV), Distraction osteogenesis(DAD), Corticotomy(Corti), Microosteoperforations (MOPS), Traditional orthodontic(OT)were identified and classified into 3 classes including surgical treatment, non-surgical treatment and traditional orthodontic treatment. According to SUCRA probability ranking of the best intervention effect, when orthodontic treatment lasted for 1 month, PBMT (90.6%), Piezo(87.4%) and MOPs(73.6%)were the top three interventions to improve the efficiency of canine tooth movement. When orthodontic treatment lasted for 2 months, Corti (75.7%), Piezo (69.6%) and LFV(58.9%)were the top three interventions for improving the mobility efficiency of canine tooth movement. When orthodontic treatment lasted for 3 months, Cort (73.3%), LLLT(68.4%)and LFV(60.8%)were the top three interventions for improving the mobility efficiency of canine tooth movement. Conclusion: PBMT and Piezo can improve the efficiency of canine tooth movement significantly after 1 month, while Corti and LFV can improve the efficiency of canine tooth movement better after 2 and 3 months.

Low-intensity pulsed ultrasound reduces alveolar bone resorption during orthodontic treatment via Lamin A/C-Yes-associated protein axis in stem cells

BACKGROUND The bone remodeling during orthodontic treatment for malocclusion often requires a long duration of around two to three years,which also may lead to some complications such as alveolar bone resorption or tooth root resorption.Low-intensity pulsed ultrasound(LIPUS),a noninvasive physical therapy,has been shown to promote bone fracture healing.It is also reported that LIPUS could reduce the duration of orthodontic treatment;however,how LIPUS regulates the bone metabolism during the orthodontic treatment process is still unclear.AIM To investigate the effects of LIPUS on bone remodeling in an orthodontic tooth movement(OTM)model and explore the underlying mechanisms.METHODS A rat model of OTM was established,and alveolar bone remodeling and tooth movement rate were evaluated via micro-computed tomography and staining of tissue sections.In vitro,human bone marrow mesenchymal stem cells(hBMSCs)were isolated to detect their osteogenic differentiation potential under compression and LIPUS stimulation by quantitative reverse transcription-polymerase chain reaction,Western blot,alkaline phosphatase(ALP)staining,and Alizarin red staining.The expression of Yes-associated protein(YAP1),the actin cytoskeleton,and the Lamin A/C nucleoskeleton were detected with or without YAP1 small interfering RNA(siRNA)application via immunofluorescence.RESULTS The force treatment inhibited the osteogenic differentiation potential of hBMSCs;moreover,the expression of osteogenesis markers,such as type 1 collagen(COL1),runt-related transcription factor 2,ALP,and osteocalcin(OCN),decreased.LIPUS could rescue the osteogenic differentiation of hBMSCs with increased expression of osteogenic marker inhibited by force.Mechanically,the expression of LaminA/C,F-actin,and YAP1 was downregulated after force treatment,which could be rescued by LIPUS.Moreover,the osteogenic differentiation of hBMSCs increased by LIPUS could be attenuated by YAP siRNA treatment.Consistently,LIPUS increased alveolar bone density and decreased vertical bone absorption in vivo.The decreased expression of COL1,OCN,and YAP1 on the compression side of the alveolar bone was partially rescued by LIPUS.CONCLUSION LIPUS can accelerate tooth movement and reduce alveolar bone resorption by modulating the cytoskeleton-Lamin A/C-YAP axis,which may be a promising strategy to reduce the orthodontic treatment process.

线上线下混合多元化教学模式在口腔医学本科留学生Orthodontics课程教学中的应用研究

目的探讨线上线下混合多元化教学模式在口腔医学本科留学生Orthodontics课程教学中的应用效果。方法于2020—2023年选取西安交通大学口腔医学院2015—2018级(大五)本科留学生为研究对象,将2015级和2016级留学生设为对照组(18名,传统教学模式),2017级和2018级留学生设为试验组(28名,线上线下混合多元化教学模式)。比较两组的教学效果。结果试验组学生的学习兴趣、课堂表现评分高于对照组(P<0.05);试验组教师的课堂参与评分高于对照组(P<0.05)。试验组的课程考核成绩高于对照组(P<0.05)。结论线上线下混合多元化教学模式在一定程度上可提高学生的学业水平和Orthodontics课程教学效果。

Comparison of Self-Perception of Esthetics and Orthodontic Treatment Needs among Dental and Non-Dental Students with Assessment by Orthodontist

Objectives: The present study was conducted to compare the self-perception of esthetics and wish for seeking orthodontic treatment among dental and non-dental students. The realistic orthodontic treatment needs were confirmed by expert orthodontist. Methods: A cross-sectional study was conducted among 255 male students (Dental—75, Medical—93 and Pharmacy—87 students). The questionnaire included 20 items covering dental esthetics self-perception (10 questions), self-confidence and psychological impact (5 questions), and the need for seeking orthodontic treatment (5 questions) on a five-point Likert scale. The realistic orthodontic treatment needs were confirmed by photographs using aesthetic component of IOTN and clinical examination for the participants and analysis of jaw models using Dental aesthetic index (DAI). Kruskal-Wallis ANOVA was used to check the significant difference between groups. Results: The overall average esthetic self-perception score for total sample was 3.83. The overall average psychological impact score for the whole sample was 2.67. The total percentage of participants who either agree or strongly agree with the question related to their perception of need for seeking orthodontic treatment was 70%. According to the assessment of orthodontic needs using AC-IOTN, 19.8% required definitive treatment. According to the assessment of orthodontic treatment needs based on DAI, 20.3% and 9.9% needed highly desirable (DAI 31 - 35) and definite need of treatment (DAI ≥ 36) respectively. Conclusion: It can be concluded that there was no difference between the esthetic perception of dental and non-dental students. The self-perception for seeking orthodontic treatment was over-reported by participants compared to real requirement as assessed by orthodontic specialist. Dental esthetics has no psychological impact on academic performance and self-confidence as perceived by study participants.

Effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats

Objective:To investigate effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats.Methods:Eighty SD rats were randomly divided into 4 groups,blank control group(group A)with 5 rats,treatment normal group(group B)with 25 rats,inflammation control group(group(group C)with 25 rats,inflammation treatment group(group D)with 25 rats.Immunohistochemistry and histomorphometric analysis was performed to measure the expression of IL-6,IL-8 and the firet molar to the recent movement in the distance.Results:The expression of IL-8 reached a maximum on day 5 and declined thereafter in group B;the expression of IL-6 reached a maximum on day 5 in group B.The expression of IL-6 and IL-8 was gradually weakened with time in group C.The expression of IL-6 and IL-8 were high,and reached a maximum on day 5 and declined thereafter in group D.AD of positive cells in group D were higher than group B at each time point(P<0.05).The time which 0.49 N orthodontic force was loaded was longer,orthodontic tooth movement distance was greater.Movement distance in group D were longer than group B(P<0.05).Conclusions:Orthodontic force as well as inflammatory stimulus can evoke the expression of IL-6 and IL-8.Under the combined effects of inflammation and orthodontic force,the expression of IL-6,IL-8will increase.

Applications of stem cells in orthodontics and dentofacial orthopedics:Current trends and future perspectives

A simple overview of daily orthodontic practice involves use of brackets, wires and elastomeric modules. However, investigating the underlying effect of orthodontic forces shows various molecular and cellular changes. Also, orthodontics is in close relation with dentofacial orthopedics which involves bone regeneration. In this review current and future applications of stem cells(SCs) in orthodontics and dentofacial orthopedics have been discussed. For craniofacial anomalies, SCs have been applied to regenerate hard tissue(such as treatment of alveolar cleft) and soft tissue(such as treatment of hemifacial macrosomia). Several attempts have been done to reconstruct impaired temporomandibular joint. Also, SCs with or without bone scaffolds and growth factors have been used to regenerate bone following distraction osteogenesis of mandibular bone or maxillary expansion. Current evidence shows that SCs also have potential to be used to regenerate infrabony alveolar defects and move the teeth into regenerated areas. Future application of SCs in orthodontics could involve accelerating tooth movement, regenerating resorbed roots and expanding tooth movement limitations. However, evidence supporting these roles is weak and further studies are required to evaluate the possibility of these ideas.

Colour stabilities of three types of orthodontic clear aligners exposed to staining agents

The aim of this study was to evaluate and compare the colour stabilities of three types of orthodontic clear aligners exposed to staining agents in vitro. Sixty clear orthodontic aligners produced by three manufacturers （Invisalign, Angelalign, and Smartee） were immersed in three staining solutions （coffee, black tea, and red wine） and one control solution （distilled water）. After 12-h and 7-day immersions, the aligners were washed in an ultrasonic cleaner and measured with a colourimeter. The colour changes （△E＊） were calculated on the basis of the Commission Internationale de I＇Eclairage L＊a＊b＊ colour system （CIE L＊a＊b＊）, and the results were then converted into National Bureau of Standards （NBS） units. Fourier transformation infrared （FT-IR） spectroscopy and scanning electron microscopy （SEM） were conducted to observe the molecular and morphologic alterations to the aligner surfaces, respectively. The three types of aligners exhibited slight colour changes after 12 h of staining, with the exception of the Invisalign aligners stained with coffee. The Invisalign aligners exhibited significantly higher AE＊ values （ranging from 0.30 to 27.81） than those of the Angelalign and Smartee aligners （AE＊ values ranging from 0.33 to 1.89 and 0.32 to 1.61, respectively, P〈O.05）. IFT-IR analysis confirmed that the polymer-based structure of aligners did not exhibit significant chemical differences before and after the immersions. The SEM results revealed different surface alterations to the three types of aligner materials after the 7-day staining. The three types of aesthetic orthodontic appliances exhibited colour stability after the 12-h immersion, with the exception of the Invisalign aligners stained by coffee. The Invisalign aligners were more prone than the Angelalign and Smartee aligners to pigmentation. Aligner materials may be improved by considering aesthetic colour stability properties.

Regular nicotine intake increased tooth movement velocity,osteoclastogenesis and orthodontically induced dental root resorptions in a rat model

Orthodontic forces have been reported to significantly increase nicotine-induced periodontal bone loss. At present, however, it is unknown, which further （side） effects can be expected during orthodontic treatment at a nicotine exposure corresponding to that of an average European smoker. 63 male Fischer344 rats were randomized in three consecutive experiments of 21 animals each （A/B/C） to 3 experimental groups （7 rats, 112/3）. （A） cone-beam-computed tomography （CBCT）; （B） histology/serology; （C） reverse- transcription quantitative real-time polymerase chain reaction （RT-qPCR）/cotinine serology--（1） control; （2） orthodontic tooth movement （OTM） of the first and second upper left molar （NiTi closed coil spring, 0.25 N）; （3） OTM with 1.89 mg-kg- 1 per day s.c. of L（- ）-nicotine. After 14 days of OTM, serum cotinine and IL-6 concentration as well as orthodontically induced inflammatory root resorption （OIIRR）, osteoclast activity （histology）, orthodontic tooth movement velocity （CBCT, within 14 and 28 days of OTM） and relative gene expression of known inflammatory and osteoclast markers were quantified in the dental-periodontal tissue （RT-qPCR）. Animals exposed to nicotine showed significantly heightened serum cotinine and IL-6 levels corresponding to those of regular European smokers. Both the extent of root resorption, osteoclast activity, orthodontic tooth movement and gene expression of inflammatory and osteoclast markers were significantly increased compared to controls with and without OTM under the influence of nicotine. We conclude that apart from increased periodontal bone loss, a progression of dental root resorption and accelerated orthodontic tooth movement are to be anticipated during orthodontic therapy, if nicotine consumption is present. Thus patients should be informed about these risks and the necessity of nicotine abstinence during treatment.

Clinical factors correlated with the success rate of miniscrews in orthodontic treatment

Miniscrews offer a reliable alternative for anchorage during orthodontic treatment,particularly for non-cooperative patients or periodontal patients with alveolar bone loss.The study aims at assessing the correlation of various clinical indicators with the success or failure of miniscrews used for anchorage during orthodontic treatment.Thirty-four consecutive patients with a cumulative total of 82 miniscrews implanted participated in the study.Generalized Estimating Equations were used to assess the correlation of various factors with success rates.The miniscrew was considered the unit of analysis clustered within site and within patient.The overall success rate of miniscrews was 90.2%.For every additional miniscrew used in a patient＇s oral cavity,the success rate was reduced by 67%.Retromandibular triangle and palatal placement and in movable mucosa resulted in lower success rate.The miniscrew length and diameter were found to correlate with success rates.Orthodontic force applied on miniscrews for uprighting purposes showed a lower success rate than that used for retraction.This study revealed that miniscrews present high success rates.The number of miniscrews used per patient,the miniscrew site placement,the soft tissue type of placement,the miniscrew length and diameter as well as the orthodontic force applied on the miniscrew showed significant correlation with success rates.

Role of third molars in orthodontics

The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too.

Reliability assessment and correlation analysis of evaluating orthodontic treatment outcome in Chinese patients

This study aimed to assess the reliability of experienced Chinese orthodontists in evaluating treatment outcome and to determine the correlations between three diagnostic information sources. Sixty-nine experienced Chinese orthodontic specialists each evaluated the outcome of orthodontic treatment of 108 Chinese patients. Three different information sources： study casts （SC）, lateral cephalometric X-ray images （LX） and facial photographs （PH） were generated at the end of treatment for 108 patients selected randomly from six orthodontic treatment centers throughout China. Six different assessments of treatment outcome were made by each orthodontist using data from the three information sources separately and in combination. Each assessment included both ranking and grading for each patient. The rankings of each of the 69 judges for the 108 patients were correlated with the rankings of each of the other judges yielding 13 873 Spearman rs values, ranging from -0.08 to ＋0.85. Of these, 90% were greater than 0.4, showing moderate-to-high consistency among the 69 orthodontists. In the combined evaluations, study casts were the most significant predictive component （R2=0.86, P〈0.000 1）, while the inclusion of lateral cephalometric films and facial photographs also contributed to a more comprehensive assessment （R2=0.96, P〈0.000 1）. Grading scores for SC＋LX and SC＋PH were highly significantly correlated with those for SC＋LX＋PH （r（SC＋LX）vs.（SC＋LX＋PH）=0.96, r（SC＋PH）vs.（SC＋LX＋PH）=0.97）, showing that either SC＋LX or SC＋PH is an excellent substitute for all three combined assessment,

Systematic review of mini-implant displacement under orthodontic loading

A growing number of studies have reported that mini-implants do not remain in exactly the same position during treatment, although they remain stable. The aim of this review was to collect data regarding primary displacement immediately straight after loading and secondary displacement over time. A systematic review was performed to investigate primary and secondary displacement. The amount and type of displacement were recorded. A total of 27 studies were included. Sixteen in vitro studies or studies using finite element analysis addressed primary displacement, and nine clinical studies and two animal studies addressed secondary displacement. Significant primary displacement was detected （6.4-24.4 μm） for relevant orthodontic forces （0.5-2.5 N）. The mean secondary displacement ranged from 0 to 2.7 mm for entire mini-implants, The maximum values for each clinical study ranged from 1.0 to 4.1 mm for the head, 1.0 to 1.5 for the body and 1,0 to 1.92 mm for the tail part. The most frequent type of movement was controlled tipping or bodily movement. Primary displacement did not reach a clinically significant level. However, clinicians can expect relevant secondary displacement in the direction of force. Consequently, decentralized insertion within the inter-radicular space, away from force direction, might be favourable. More evidence is needed to provide quantitative recommendations.

Periodontally accelerated osteogenic orthodontics with platelet-rich fibrin in an adult patient with periodontal disease:A case report and review of literature

BACKGROUND In the clinical scenario,adult patients with periodontal diseases and dental malformation,characterized by dental crowding in lower anterior teeth with the thin biotype,often require orthodontic treatment.This case report aimed to evaluate the clinical and radiographic outcomes of periodontally accelerated osteogenic orthodontics(PAOO)combined with autologous platelet-rich fibrin(PRF)in an adult patient with class I malocclusion along with dental crowding,a thin periodontal biotype,and buccal plate deficiency.CASE SUMMARY A 32-year-old female complaining of dental crowding and gingival bleeding was referred to the orthodontic clinic.The patient underwent periodontal risk assessment prior to orthodontic treatment.She was diagnosed with a high risk of gingival recession due to dental crowding,root prominence,loss of buccal plates,and a thin gingival tissue biotype.The treatment regimen included PAOO combined with autologous PRF for alveolar augmentation and interproximal enamel reduction for moderate dental crowding.Clinically,PAOO-assisted orthodontic tooth movement in this case showed enhanced periodontium remodeling.Radiographic outcomes also showed statistically significant improvements(P<0.01)in the mandibular buccal alveolar bone.CONCLUSION This case report suggests the combination of autologous PRF with PAOO to enhance bone augmentation and long-term tissue support in adult orthodontic patients with periodontal disease.

Factors Influencing Subjective Orthodontic Treatment Need and Culture-related Differences among Chinese Natives and Foreign Inhabitants

Aim The aim of this survey was to compare Chinese natives and foreign inhabitants in Chengdu, China, with respect to： （1） attitudes towards dental appearance, （2） subjective orthodontic treatment need, and （3） the main factors influencing orthodontic treatment need. Methodology A total of 522 subjects, including 227 foreign inhabitants and 295 Chinese natives in Chengdu participated in the survey. A simple random sampling method was adopted and a face-to-face interview was conducted at some public sites using a questionnaire. Data was entered by two persons synchronously using Epidata 3.0, and SPSS 13.0 was used to analyze these data. Results 89.0% of foreign inhabitants were satisfied with their teeth compared to only 46.8% of Chinese natives. Females were more dissatisfied with their teeth than males. Chinese natives put improving appearance as the top priority （55.9%） for seeking orthodontic treatment; however, in foreign inhabitants, the main reason for seeking treatment was to improve masticatory function（44.1%）, followed by ＂to be pretty＂ （35.2%）. The importance of well-aligned teeth and self-perception of psychosocial impact of malocclusion were the same two main factors influencing subjective orthodontic treatment need （P〈0.05） in foreign inhabitants and Chinese natives. Sub- jective orthodontic treatment need between the two target groups was significantly different （P〈0.05）. Conclusion （1） It was very common that Chinese natives were dissatisfied with their dental appearance, and their subjective orthodontic treatment needs were high. （2） There were some differences in orthodontic treatment motives between the two target groups. （3） There were differences in subjective orthodontic treatment needs between foreign inhabitants and Chinese natives. However, the prominent influential factors were almost the same. There may be benefit to understanding subjective orthodontic needs of different races.

Effect of maxillary expansion on orthodontics

Objective:To explore the effect of maxillary expansion on orthodontics.Methods:Eight beagle dogs were randomly divided into two groups,with 4 dogs in each group.Dogs in group1 were executed immediately and received the direct physical measurement.The magnetic expansion appliance was used in group 2 for the maxillary expansion.After the expansion,the model was taken again and they were executed after cone beam CT(CBCT) scanning.The model measurement method was adopted in group 1 to measure the dental measurement indicators and width of base bone arch.The CBCT measurement method was employed to measure the above dental indicators and bone indicators.The difference in the indicators measured by different methods was compared and analyzed.Results:Before the expansion,there was no significant difference in the bone measurement indicators between the CBCT measurement method and direct physical measurement method.After the expansion,there was no significant difference in indicators between the CBCT measurement method and direct physical measurement.But there was significant difference among the model measurement method,CBCT measurement method and direct physical measurement method.There was the significant difference in the dental indicators between the CBCT measurement method and model measurement,as well as the bone indicators of posterior marginal spacing of greater palatine foramen,posterior marginal spacing of incisive foramen,width of base bone arch and spacing of implant anchorage.Conclusions:There is no significant difference between the effect of CBCT measurement method and direct physical measurement method,but CBCT is significantly better than the model measurement.

Effect of low level laser therapy on dental pulp during orthodontic movement

AIM: To validate the protocol described here to be used in future clinical trials related to the effect of laser therapy on dental pulp. METHODS: Histologically treated samples from eight human healthy premolar teeth obtained from the middle root level were distributed in four groups: group 1(G1) absolute control; group 2(G2) only laser irradiation; group 3(G3) exposed only to orthodontics; and group 4(G4) treated with orthodontics and laser. Laser treatment was performed at 830 nm wavelength, 100 mW(energy 80 J/cm2, 2.2 J), for 22 s in the vestibular surface and 22 s in the palatal surface, 1 mm away from the dental root mucosa. Three staining methods were performed: hematoxylin-eosin(HE), Masson's Trichrome method and Gomori's method.RESULTS: The pulp histology parameters were evaluated and the results classified in to 3 parts: an inflammatory response, soft tissue response(dental pulp) and hard tissue response(dentin and predentin). There was no inflammation(chronic or acute) in any of the evaluated groups. The zones of pulp necrosis were found in one premolar of G3 and in one of G4; in groups G2 and G4 there was higher angiogenesis than in the other two groups. G4 group presented the highest level of vascularization. A reduced nerve density was observed in G3. A G2 specimen showed increased nerve density. A higher rate of calcification was observed in G1 compared to G2. Denticles, either real or false, were observed in G1, G2 and G3. Sclerosis of dentin and focal dentin loss was observed among all the groups. Secondary dentin was present in one sample in G1 and G2. A necrosis zone was found in one sample of G3 and G4. No differences between groups were observed in the odontoblast irregularity layer but the layer was wider in the group treated with laser only. A notable difference was detected in reduction of the cell-free layer between the groups G1 and G4. The findings in pulp tissue favor its adaptative response against dental movement induced by orthodontics. No definitive conclusions may be derived as this is a pilot study. CONCLUSION: The protocol described here was shown to be an effective method to evaluate changes in dental pulp submitted to low level laser in teeth under orthodontic movement.

Effect of low-level laser therapy on tooth-related pain and somatosensory function evoked by orthodontic treatment

Low-level laser therapy(LLLT) may have an effect on the pain associated with orthodontic treatment. The aim of this study was to evaluate the effect of LLLT on pain and somatosensory sensitization induced by orthodontic treatment. Forty individuals(12–33 years old; mean ± standard deviations: 20.8 ± 5.9 years) scheduled to receive orthodontic treatment were randomly divided into a laser group(LG) or a placebo group(PG)(1:1). The LG received LLLT(810-nm gallium-aluminium-arsenic diode laser in continuous mode with the power set at 400 mW, 2 J·cm–2) at 0 h, 2 h, 24 h, 4 d, and 7 d after treatment, and the PG received inactive treatment at the same time points. In both groups, the non-treated side served as a control. A numerical rating scale(NRS) of pain, pressure pain thresholds(PPTs), cold detection thresholds(CDTs), warmth detection thresholds(WDTs), cold pain thresholds(CPTs), and heat pain thresholds(HPTs) were tested on both sides at the gingiva and canine tooth and on the hand. The data were analysed by a repeated measures analysis of variance(ANOVA). The NRS pain scores were significantly lower in the LG group(P = 0.01). The CDTs,CPTs, WDTs, HPTs, and PPTs at the gingiva and the PPTs at the canine tooth were significantly less sensitive on the treatment side of the LG compared with that of the PG(P < 0.033). The parameters tested also showed significantly less sensitivity on the nontreatment side of the LG compared to that of the PG(P < 0.043). There were no differences between the groups for any quantitative sensory testing(QST) measures of the hand. The application of LLLT appears to reduce the pain and sensitivity of the tooth and gingiva associated with orthodontic treatment and may have contralateral effects within the trigeminal system but no generalized QST effects. Thus, the present study indicated a significant analgesia effect of LLLT application during orthodontic treatment.Further clinical applications are suggested.

TNF-<i>α</i>and RANKL facilitates the development of orthodontically-induced inflammatory root resorption

Background: The objective of this study was to determine the levels of tumor necrosis factor-alpha (TNF-α) and receptor activator of NF-kB ligand (RANKL) in the gingival crevicular fluid (GCF) in patients with severe root resorption after orthodontic treatment. Materials and Methods: Ten patients who had been receiving orthodontic treatment (5-control subjects and 5-severe root resorption subjects) participated in this study. GCF was collected from all patients. Subjects with severe root resorption (>1/3 of the original root length) were identified. Control group subjects with no loss of the root structure undergoing orthodontic treatment were also identified. The GCF was collected non-invasively from the mesial and distal sides of each of the upper central and lateral incisors using filter paper strips. The eluted GCF was used for a Western blot analysis with Antibodies against TNF-α and soluble RANKL (sRANKL). Ten male 6-week-old Wistar rats were subjected to orthodontic force of 50 g to induce a mesially tipping movement of the upper first molars for 7 days. The expression levels of TNF-α and RANKL proteins were determined in periodontal ligament (PDL) by immunohistochemical analysis. Results: The Western blot analysis showed that the TNF-α and sRANKL expressions were significantly higher in the severe root resorption group than in the control group. In the experimental tooth movement in vivo, resorption lacunae with multinucleated cells were observed in 50 g group. The immunoreactivity for TNF-α and RANKL was detected in PDL tissue subjected to the orthodontic force on day 7. Conclusion: These results suggest that TNF-α and RANKL play important roles in inducing or facilitating the development of orthodontically-induced inflammatory root resorption (OIIRR).