Introducing a User-Friendly Technique for Treatment of Palatally-Impacted Canines with the Aid of Temporary Anchorage Devices.

Treatment of impacted canine teeth is a challenge for most clinicians, especially in adult patients with high risk of ankylosis. Conventionally, leveling and alignment of the teeth are first performed and after heavy arch wire placement in slot of brackets, de-impaction force is applied. However, this method has some disadvantages, such as inability to detect ankylosis of the impacted tooth until load application, risk of root resorption of incisors or necrosis of them, distortion of dental arch form, the need for early extraction of primary canines, which is esthetically unfavorable for patients, and long-term presence of fixed orthodontic appliances in the oral cavity. This study aims to introduce approach that can be easily used by busy clinicians to guide palatally impacted canines into the dental arch using a cantilever spring supported by two palatal miniscrews prior to the initiation of fixed orthodontic treatment, and report some cases treated with this technique. This technique does not have the shortcomings of the conventional technique. In addition, the total duration of treatment, and duration of presence of orthodontic appliances in the oral cavity are shorter than the conventional technique. In addition, is less technique sensitive and do not need time complex and time consuming wire bending.

Effectiveness of MI Paste Plus and Remin Pro on remineralization and color improvement of postorthodontic white spot lesions.

BACKGROUND: This clinical trial investigated the effectiveness of two remineralizing creams on regression of white spot lesions (WSLs) after orthodontic therapy. MATERIALS AND METHODS: The study included patients with WSLs on their upper anterior teeth who recently completed orthodontic treatment at the Department of Orthodontics of Mashhad Dental School and two private offices. The participants were randomly assigned into three groups by treatment: (1) a 12-week regimen of a cream containing casein phosphopeptide-amorphous calcium phosphate and fluoride (MI Paste Plus); (2) a 12-week regimen of a cream containing hydroxyapatite and fluoride (Remin Pro); and (3) usual home care (control). Thirty-nine patients participated and three withdrew. The main outcomes including area, mineral content, and color of WSLs were measured at enrolment and 4, 8, and 12 weeks later, respectively. Blinding was applied for outcome assessment only. The data were analyzed by analysis of variance and repeated measures analysis at the statistical significance of P < 0.05. RESULTS: Over a 3-month period, the application of both MI Paste Plus and Remin Pro caused significantly greater reduction in area and significantly higher increase in mineral content of WSLs compared to the control group (P < 0.05). The appearance of WSLs improved significantly in both experimental groups (P < 0.05), but not in the control group. No side effect was observed throughout the experiment. CONCLUSION: The application of either MI Paste Plus or Remin Pro was effective in reducing the area, increasing the mineral content and improving the appearance of demineralized enamel, indicating that these products could be recommended for managing postorthodontic WSLs.

Retentive Strength of Orthodontic Bands Cemented with Amorphous Calcium Phosphate-Modified Glass Ionomer Cement: An In-Vitro Study.

OBJECTIVES: The aim of this study was to evaluate and compare the retentive strength of orthodontic bands cemented with amorphous calcium phosphate (ACP)-containing and conventional glass ionomer cements (GICs). MATERIALS AND METHODS: One-hundred-and-twenty mandibular third molars were embedded in acrylic resin blocks with the buccal surface of crowns perpendicular to the base of the mold. The teeth were randomly divided into four groups containing 30 teeth each. Groups 1 and 3 were cemented using conventional GIC and groups 2 and 4 were cemented using ACP-containing orthodontic cement. Groups 1 and 2 without thermocycling, and groups 3 and 4 after thermocycling (5000 cycles, 5° to 55°C) were tested for retentive strength using a universal testing machine (crosshead speed of 1mm/minute). Two-way ANOVA was performed to compare the retentive strength of the groups. RESULTS: The highest retentive strength belonged to group 1, and it was significantly higher than that of group 2 (P<0.001) and group 3 (P=0.02). The mean strength for group 2 was significantly lower than that of group 1 (P<0.001) and group 4 (P=0.04). CONCLUSIONS: Although retentive strength decreased when ACP was added to GIC, the retentive strength of the samples cemented by ACP-containing GIC was remarkably high after thermocycling. It seems that in the oral cavity, ACP-containing GIC provides sufficient strength to endure forces applied on posterior teeth.

Cementum and dentin repair following root damage caused by the insertion of self-tapping and self-drilling miniscrews.

OBJECTIVE: The aim of this study was to evaluate the histological responses of cementum, root dentin, and pulp following intentional root injuries caused via self-tapping and self-drilling miniscrews. MATERIALS AND METHODS: Fourteen patients (with a mean age of 15.7 years and age range of 14-18 years) who were scheduled for the extraction of all four first premolars as part of their orthodontic treatment plan participated in this study. The roots of the right and the left quadrants' first premolars were designedly injured using self-tapping miniscrews and self-drilling miniscrews, respectively. Teeth were extracted eight weeks after the injury. Cementum repair was assessed through histological examinations. RESULTS: In this study, 40 teeth (75.4%) showed reparative cementum formation and 13 teeth (24.5%) showed no repair. There was no significant difference between the two groups regarding the formation of reparative cementum (P = 0.3). In all examined teeth, the inflammatory response of the pulp to the cold test was within the normal range. CONCLUSION: This study showed that in most cases, the healing of cementum was observed eight weeks after the injury and the two methods of miniscrew insertion showed no significant difference when it comes to the healing process.

The effect of canine disimpaction performed with temporary anchorage devices (TADs) before comprehensive orthodontic treatment to avoid root resorption of adjacent teeth.

OBJECTIVE: The aim of this study was to evaluate the movement of impacted canines away from the roots of neighboring teeth before full-mouth bracket placement, performed by means of TADs to decrease undesired side effects on adjacent teeth. METHODS: The study sample consisted of 34 palatally impacted canines, being 19 in the experimental group and 15 in the control group. In the experimental group, before placement of brackets, the impacted canine was erupted by means of miniscrews. In the control group, after initiation of comprehensive orthodontics, canine disimpaction was performed by means of a cantilever spring soldered to a palatal bar. At the end of treatment, volume of lateral incisors and canine root resorption were measured and compared by means of a CBCT-derived tridimensional model. Visual Analogue Scale (VAS) score, bleeding on probing (BOP) and gingival index (GI) were recorded. Clinical success rate was also calculated. RESULTS: The volume of root resorption of lateral teeth in the control group was significantly greater than in the experimental group (p < 0.001). At the end of treatment, VAS score, GI and BOP were not significantly different between the two groups. CONCLUSION: Based on our results, it seems that disimpaction of canines and moving them to the arch can be done successfully carried out with minimal side effects by means of skeletal anchorage.

Evaluation of the effects of subgingival injection of Simvastatin on space re-opening after orthodontic space closure in adults.

Background. This clinical trial evaluated the effect of Simvastatin on space re-opening after orthodontic space closure and its effect on the gingival index (GI) and clinical attachment loss (CAL). Methods. 16 females, 25-40 years old, with spaces between anterior mandibular teeth due to chronic periodontitis were participated in this study. The patients were randomly divided into control and experimental groups. In the experimental group, 1.2% Simvastatin gel and in the control group, 0.9% sodium chloride as a placebo was injected into the pocket depth of the six anterior teeth. The amount of space reopening, GI and CAL were measured. Results. No serious complications were observed during interventions and follow-up periods. Space re-opening was significantly reduced in patients receiving Simvastatin (P < 0.001). Moreover, GI reduction was significantly greater in Sim-vastatin group compared to the control group (P < 0.001). However, CAL did not demonstrate a significant difference between the groups. Conclusion. Simvastatin may decrease space re-opening after orthodontic space closure in human anterior teeth.

The effect of canine disimpaction performed with temporary anchorage devices (TADs) before comprehensive orthodontic treatment to avoid root resorption of adjacent teeth

ABSTRACT Objective: The aim of this study was to evaluate the movement of impacted canines away from the roots of neighboring teeth before full-mouth bracket placement, performed by means of TADs to decrease undesired side effects on adjacent teeth. Methods: The study sample consisted of 34 palatally impacted canines, being 19 in the experimental group and 15 in the control group. In the experimental group, before placement of brackets, the impacted canine was erupted by means of miniscrews. In the control group, after initiation of comprehensive orthodontics, canine disimpaction was performed by means of a cantilever spring soldered to a palatal bar. At the end of treatment, volume of lateral incisors and canine root resorption were measured and compared by means of a CBCT-derived tridimensional model. Visual Analogue Scale (VAS) score, bleeding on probing (BOP) and gingival index (GI) were recorded. Clinical success rate was also calculated. Results: The volume of root resorption of lateral teeth in the control group was significantly greater than in the experimental group (p < 0.001). At the end of treatment, VAS score, GI and BOP were not significantly different between the two groups. Conclusion: Based on our results, it seems that disimpaction of canines and moving them to the arch can be done successfully carried out with minimal side effects by means of skeletal anchorage.

RESUMO Objetivo: o objetivo do presente estudo foi avaliar o uso de dispositivos de ancoragem temporária (DATs) para a movimentação de caninos impactados, afastando-os das raízes dos dentes vizinhos, antes da colagem dos braquetes em todos os dentes, com o objetivo de minimizar os efeitos colaterais indesejáveis nesses dentes adjacentes. Métodos: a amostra consistiu de 34 caninos impactados por palatino, sendo 19 no grupo experimental e 15 no grupo controle. No grupo experimental, antes da colagem dos braquetes, os caninos impactados foram tracionados utilizando-se mini-implantes. No grupo controle, após o início do tratamento ortodôntico, a desimpacção dos caninos foi realizada com uma mola em cantiléver soldada a uma barra transpalatina. Ao fim do tratamento, os valores referentes à reabsorção radicular nos incisivos laterais e caninos foram medidos e comparados por meio de modelos tridimensionais reconstruídos a partir de TCFCs. Foram também registrados os escores relativos à dor sentida pelos pacientes, usando uma escala visual analógica (VAS); além do Índice de Sangramento à Sondagem (ISS) e do Índice Gengival (IG). O índice de sucesso clínico também foi calculado. Resultados: o volume de reabsorção radicular nos incisivos laterais no grupo controle foi significativamente maior do que no grupo experimental (p < 0,001). Ao fim do tratamento, não houve diferença significativa entre os dois grupos quanto aos escores relativos à VAS, ao IG e ISS. Conclusão: esses resultados sugerem que a desimpacção de caninos e a movimentação deles para a arcada dentária podem ser realizadas, com sucesso e com mínimos efeitos colaterais, por meio da ancoragem esquelética.

Incorporation of CPP-ACP into Luting and Lining GIC: Influence on Wear Rate (in the Presence of Artificial Saliva) and Compressive Strength.

The improvement of mechanical and antibacterial properties of glass ionomer cements (GICs) is an important goal in dental research. In this way, modification of GIC with caries preventive and remineralizing materials such as casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is a new strategy to enhance its anticariogenic properties and the remineralization of teeth. However, one main concern is that adding CPP-ACP may have negative effects on the mechanical properties of GIC. This study investigated the influence of adding CPP-ACP on the wear rate (in the presence of artificial saliva) and compressive strength of luting and lining glass ionomer cement. CPP-ACP was incorporated into a luting and lining glass ionomer cement at different percentages (1, 1.56, and 2%). Wear rate and compressive strength were measured for each group using Pin-on-Disk tribometer device (in artificial saliva condition) and universal testing machine, respectively. The wear test was carried out in the presence of artificial saliva for better simulation of the oral environment. Our results demonstrated that increasing the percentage of CPP-ACP from 0 up to 1.56% (w/w), caused a decrease of 19% in the wear rate. However, at 2% (w/w) CPP-ACP, the wear rate increased. Compressive strength was improved by 31% when the CPP-ACP concentration was increased to 1.56% (w/w), but decreased when the concentration was raised to 2% (w/w). In conclusion, adding 1.56% CPP-ACP into luting and lining glass ionomer cement appears to provide an acceptable combination of two important mechanical properties, compressive strength and wear rate.

How Is the Enamel Affected by Different Orthodontic Bonding Agents and Polishing Techniques?

OBJECTIVES: The objective of this study was to assess the effect of new bonding techniques on enamel surface. MATERIALS AND METHODS: Sixty upper central incisors were randomly divided into two equal groups. In the first group, metal brackets were bonded using TransbondXT and, in the second group, the same brackets were bonded with Maxcem Elite. The shear bond strength (SBS) of both agents to enamel was measured and the number and length of enamel cracks before bonding, after debonding and after polishing were compared. The number of visible cracks and the adhesive remnant index (ARI) scores in each group were also measured. RESULTS: There were significantly more enamel cracks in the Transbond XT group after debonding and polishing compared to the Maxcem Elite group. There was no significant difference in the length of enamel cracks between the two groups; but, in each group, a significant increase in the length of enamel cracks was noticeable after debonding. Polishing did not cause any statistically significant change in crack length. The SBS of Maxcem Elite was significantly lower than that of Transbond XT (95% confidence interval). CONCLUSION: Maxcem Elite offers clinically acceptable bond strength and can thus be used as a routine adhesive for orthodontic purposes since it is less likely to damage the enamel.

Periodontal changes following molar intrusion with miniscrews.

BACKGROUND: With the introduction of skeletal anchorage system, recently it is possible to successfully intrude molar teeth. On the other hand, there have been concerns about periodontal changes associated with intrusion and there are few studies on this topic, especially for posterior teeth. MATERIALS AND METHODS: Ten female patients were enrolled in this study. Maxillary molar intrusion was achieved by inserting two miniscrews and a 17 × 25 titanium molybdenum alloy spring. Crestal height changes were evaluated at three intervals including: Baseline (T0), end of active treatment (T1) and 6 months after retention (T2). Other variables including probing depth, gingival recession, attachment level and bleeding on probing were evaluated by clinical measurements in the three above mentioned intervals. One-sample Kolmogrov-Smirnov test ascertained the normality of the data. For all patients, the changes in tooth position and crestal height were evaluated using one-sample t-test. (P < 0.05). RESULTS: Supra-erupted molars were successfully intruded a mean of 2.1 ± 0.9 mm during active treatment (T0-T1). A mean bone resorption of 0.9 ± 0.9 mm in mesial crest and 1 ± 0.8 mm in distal crest had occurred in total treatment (T0-T2). A mean of 0.6 ± 1.4 mm bone was deposited on mesial crest during the retention period (T1-T2) following tooth relapse. On average, 0.8 ± 0.4 mm attachment gain was obtained. Gingival margin coronalized a mean of 0.8 ± 0.6 mm throughout the entire treatment. Probing depth showed no significant change during treatment. CONCLUSION: Within the limitations of this study, these results suggest that not only periodontal status was not negatively affected by intrusion, but also there were signs of periodontal improvement including attachment gain and shortening of clinical crown height.

Effect of fluoride on nickel-titanium and stainless steel orthodontic archwires: an in-vitro study.

OBJECTIVES: The commonly used Nickel-Titanium (NiTi) archwires in orthodontic treatment are often exposed to fluoride-containing mouthwashes. The aim of this in-vitro study was to evaluate and compare the corrosion resistance of three commercially available NiTi archwires exposed to 0.05 wt% and 0.2 wt% fluoride mouthwashes. MATERIALS AND METHODS: Three different types of NiTi archwires, 0.016″ in diameter, from Dentaurum, Global, and GAC, and a stainless steel archwire from Dentaurum were examined to assess their corrosion resistance in Fusayama-Meyer artificial saliva and in two other artificial saliva containing 0.05 wt% and 0.2 wt% sodium fluoride (NaF). After the primary setup of wires, they were tested by potentiodynamic and potentiostatic polarization and corrosion potential/time analyses. Their surfaces were evaluated using a scanning electronic microscope (SEM). RESULTS: The results showed that all the wires were passive in artificial saliva. In contrast, by adding fluoride ions to the solution, the decrease in the archwires' corrosion resistance was in direct proportion to the increase in fluoride concentration. CONCLUSION: The NiTi wires experienced deterioration of their corrosion properties under the effect of fluoride but not as much as the stainless steel archwires.

Covering of fiber-reinforced composite bars by adhesive materials, is it necessary to improve the bond strength of lingual retainers?

OBJECTIVES: The objectives were to evaluate the shear bond strength (SBS) of fiber-reinforced composite (FRC) retainers when bonding them to teeth with and without covering the FRC bars using two different adhesive systems. MATERIALS AND METHODS: Hundred and twenty extracted human maxillary premolars were randomly divided into eight groups (n = 15). FRC bars (4 mm length, Everstick Ortho(®), Stick Tech, Oy, Turku, Finland) were bonded to the proximal (distal) surfaces of the teeth using two different adhesives (Tetric Flow [TF, Ivoclar Vivadent, Switzerland] and resin-modified glass ionomer cement [RMGIC, ODP, Vista, CA, USA]) with and without covering with the same adhesive. Specimens were exposed to thermocycling (625 cycles per day [5-55°C, intervals: 30 s] for 8 days). The SBS test was then performed using the universal testing machine (Zwick, GMBH, Ulm, Germany). After debonding, the remaining adhesive on the teeth was recorded by the adhesive remnant index (0-3). RESULTS: The lowest mean SBS (standard deviation) was found in the TF group without covering with adhesive (12.6 [2.11] MPa), and the highest bond strength was in the TF group with covering with adhesive (16.01 [1.09] MPa). Overall, the uncovered RMGIC (15.65 [3.57] MPa) provided a higher SBS compared to the uncovered TF. Covering of FRC with TF led to a significant increase in SBS (P = 0.001), but this was not true for RMGIC (P = 0.807). Thermal cycling did not significantly change the SBS values (P = 0.537). Overall, eight groups were statistically different (ANOVA test, F = 3.32, P = 0.034), but no significant differences in bond failure locations were found between the groups (Fisher's exact tests, P = 0.92). CONCLUSIONS: The present findings showed no significant differences between SBS of FRC bars with and without covering by RMGIC. However, when using TF, there was a significant difference in SBS measurements between covering and noncovering groups. Therefore, the use of RMGIC without covering FRC bars can be suggested, which can be validated with in vivo studies.

Evaluation of health related quality of life changes after initial orthodontic treatment.

PURPOSE: To evaluate the changes of Oral Health Related Quality of Life (OHRQoL) in patients after the placement of a fixed orthodontic appliance. MATERIALS AND METHODS: This prospective study consisted of 148 adolescents (97 girls and 51 boys) between the ages of 14 and 17 who were patients of an orthodontic clinic. OHRQoL was assessed by a modified questionnaire that evaluated four domains: oral symptoms, functional limitations as well as emotional and social well-being in three time frames: before bonding and banding (T(0)), two months after initiating orthodontic treatment (T(1)) and six months after initiating orthodontic treatment (T(2)). The repeated measures test was used to compare the relative changes of OHRQoL among the different time frames. RESULTS: There were no significant differences between the levels of OHRQoL and its domains for boys or girls at any time point. The overall level of OHRQoL decreased significantly at T(1) relative to T(0); however, the emotional well-being domain improved at T(1) in comparison to T(0). At T(2), the OHRQoL level increased significantly relative to T(0) in all domains. CONCLUSION: The patients' quality-of-life level decreased by initiating orthodontic treatment; however, during that period, emotional well-being increased. As orthodontic treatment progressed, the quality of life level increased.

Which Factors Affect Dental Esthetics and Smile Attractiveness in Orthodontically Treated Patients?

OBJECTIVES: This study aimed to find the factors that affect dental esthetics and smile attractiveness in orthodontically treated patients according to laypeople's judgment, and to determine whether there is any relationship between dental and smile esthetics. MATERIALS AND METHODS: Using the Q-sort technique, 60 laypersons (30 males, 30 females) rated dental and smile photographs of 48 orthodontically treated patients based on their degree of attractiveness. Dental and smile parameters of each rated image were measured by Smile Analyzer software. The Student's t-test and chi-square test were used to compare dental and smile parameters between attractive and unattractive images. The logistic regression was used to assess which variables predicted dental and smile esthetics in treated individuals. RESULTS: The philtral to commissural height ratio and gingival display were significantly different in attractive and unattractive smiles (P=0.003 and P=0.02, respectively). None of the dental variables were found to be a determinant of dental esthetics at the end of the orthodontic treatment (P>0.05). According to the judgment of all raters (female and male) and the male raters' judgment, smile attractiveness could be predicted by philtral to commissural height ratio and buccal corridor ratio (P<0.05). There was no statistically significant relationship between dental esthetics and smile attractiveness in orthodontically treated patients (P>0.05). CONCLUSION: The philtral to commissural height ratio and buccal corridor ratio can be considered as predictors of smile attractiveness in orthodontically treated patients. Achieving dental esthetics at the end of orthodontic treatment does not guarantee smile attractiveness.

Evaluation of relationship between oral health-related quality of life and occlusion traits among female adolescents.

BACKGROUND: The aim of this study was to determine the impact of malocclusions on oral health-related quality of life (OHRQOL) among female adolescents. MATERIALS AND METHODS: This is an observational cross-sectional descriptive study. A total of 129 female students with age ranges between 14 and 17 years old were randomly selected from Mashhad (Iran) high schools and were asked to fill out an OHRQOL questionnaire included in four parts: Oral symptoms, functional limitations, emotional well-being and social well-being. Each participant was clinically examined to assess her malocclusion according to the index of complexity, outcome and need (ICON) and finally the data were entered to SPSS 11.5 and the relation between these two variables was assessed with Pearson correlation test. P < 0.05 was considered as statistically significant. RESULTS: There was statistically significant correlation between ICON scores and quality of life (P = 0.0176). Being separately assessed, among four parts of the questionnaire, only emotional well-being was significantly correlated with the ICON score (P < 0.05). CONCLUSION: Malocclusions play a vital role in OHRQOL. However, in female adolescents among four parts of OHRQOL, emotional well-being had significant relationship with malocclusions.

Analysis of Different Positions of Fiber-Reinforced Composite Retainers versus Multistrand Wire Retainers Using the Finite Element Method.

Background. The aim of this study was to evaluate root displacement of the lower incisors fixed with FRC in different positions versus FSW retainers using the finite element method. Materials and Methods. 3D finite element models were designed for a mandibular anterior segment: Model 1: flexible spiral wire bonded to the lingual teeth surfaces, Model 2: FRC bonded to the upper third of lingual teeth surfaces, and Model 3: FRC bonded to the middle third. FE analysis was performed for three models and then tooth displacements were evaluated. Results. In contrast to lateral incisors and canines, the FSW retainer caused the central teeth to move more than the teeth bonded with FRC in both loadings. Comparison between Models 2 and 3 (in vertical loading) showed that FRC retainers that bonded at the upper third of lingual teeth surfaces made central and canine teeth move less than FRC retainers bonded at the middle third; however, for lateral teeth it was the opposite. Conclusion. FRC retainers bonded at the upper third of lingual teeth surfaces make central and canine teeth move less than FRC retainers bonded at the middle third in vertical loading; however, for lateral teeth it was the opposite.

A comparative study of treatment outcomes between begg and edgewise orthodontic systems in class I cases.

BACKGROUND: The purpose of this study was to compare the occlusal peer assessment rating (PAR) index in Class I patients treated by means of Begg and Edgewise methods. MATERIALS AND METHODS: The pre- and post-treatment study models of Class I patients, referred to two private clinics, treated with Begg method (n = 30) and standard Edgewise method (n = 30), were reviewed retrospectively using PAR index including dental displacements, buccal occlusion (anteroposterior, vertical and transverse), overjet, overbite and midline parameters. The changes in PAR indices were analyzed using paired t-test. A P < 0.05 was considered as statistically significant. RESULTS: There was no significant difference in sex and age distribution between the two groups. The improvement of buccal occlusion in patients treated by Begg method (1.51 ± 0.39) was significantly higher than that of patients treated by Edgewise method (0.28 ± 0.39). The duration of treatment in Begg method (17.8 ± 1.3 months) was significantly shorter than that of Edgewise method (23.7 ± 1.3 months). However, there were no significant differences between the two methods in terms of total PAR index, dental displacements, overjet, overbite and midline. CONCLUSION: In conclusion, findings of the present study indicated that Begg method might be associated with better improvement of buccal occlusion and shorter duration of treatment.

The effect of low level laser therapy on the rate of tooth movement and pain perception during canine retraction.

AIMS: This study investigated the effect of an 810 nm gallium-aluminum-arsenide (Ga-Al-As) laser on tooth movement velocity and pain perception during canine retraction in orthodontic patients. METHODS: This single blind study included 20 patients requiring upper first premolar extraction on both sides. One half of the upper arch was irradiated with a GaAlAs laser (810 nm, 200 mW, 10 points, 21.4 J/cm2/point) and the other half served as the placebo group. Irradiation was performed just after loading canine retraction forces and on days 3, 7, 11 15 over the first month. At the 28th day, the coil spring was adjusted and the same protocol was continued. The extension of tooth movement and the degree of mesiodistal inclination of canines were measured on the study models prepared at 0, 28 and 56 days. The patients were also asked to bite on plastic blocks to examine the degree of pain perceived on canines at both sides. RESULTS: There was no significant difference either in the speed of canine movement or in its degree of mesiodistal inclination between the laser and placebo sides. The pain perception did not differ significantly between the two groups at any of the treatment appointments. CONCLUSION: Low level laser therapy (LLLT), with the parameter settings used in this study, did not affect canine movement velocity and its degree of mesiodistal inclination and did not influence pain perceived by the patients.

Comparative evaluation of the effect of Er:YAG laser and low level laser irradiation combined with CPP-ACPF cream on treatment of enamel caries.

OBJECTIVES: This study investigated the effectiveness of low power red and infrared lasers and that of Er:YAG laser, in association with CPP-ACPF cream, on remineralization of white spot lesions. STUDY DESIGN: Fifty intact premolars were immersed in a demineralization solution for 10 weeks to induce caries like lesions and then were divided into five groups. In group 1, the teeth were covered with a CPP-ACPF cream for 3 minutes and then irradiated with a low power red laser (660 nm, 200 mW) for 1 minute through the cream. In group 2, the treatment was the same as that in group 1, but an infrared laser (810 nm, 200 mW) was employed. The specimens in group 3 were irradiated with an Er:YAG laser (100 mJ, 10 Hz) combined with CPP-ACPF. In group 4, the CPP-ACPF cream was applied for 4 minutes and group 5 was submitted to neither laser nor CPP-ACPF. The micro Vickers hardness was compared at 20, 60 and 100 µ from the enamel surface among the groups. RESULTS: The highest microhardness was observed in the low power red and Er:YAG laser groups and the lowest one belonged to the CPP-ACPF alone and control groups. However, no significant difference was found in microhardness of the experimental groups at any of the evaluation depths (p>0.05). CONCLUSIONS: With the laser parameters used in this study, neither the combined application of Er:YAG laser with CPP-ACPF nor the combination of low power lasers with CPP-ACPF provided a significant increase in remineralization of enamel caries. Key words:Low level laser, Er:YAG, laser, enamel caries, CPP-ACP, microhardness, white spot lesion.

Evaluation of shear bond strength of orthodontic brackets using trans-illumination technique with different curing profiles of LED light-curing unit in posterior teeth.

BACKGROUND: Although using light-cured composites for bonding orthodontic brackets has become increasingly popular, curing light cannot penetrate the metallic bulk of brackets and polymerization of composites is limited to the edges. Limited access and poor direct sight may be a problem in the posterior teeth. Meanwhile, effectiveness of the trans-illumination technique is questionable due to increased bucco-lingual thickness of the posterior teeth. Light-emitting diode (LED) light-curing units cause less temperature rise and lower risk to the pulpal tissue. The purpose of this study was to evaluate the clinical effectiveness of trans-illumination technique in bonding metallic brackets to premolars, using different light intensities and curing times of an LED light-curing unit. METHODS: Sixty premolars were randomly divided into six groups. Bonding of brackets was done with 40- and 80-s light curing from the buccal or lingual aspect with different intensities. Shear bond strengths of brackets were measured using a universal testing machine. Data were analyzed by one-way analysis of variance test and Duncan's post hoc test. RESULTS: The highest shear bond belonged to group 2 (high intensity, 40 s, buccal) and the lowest belonged to group 3 (low intensity, 40 s, lingual). Bond strength means in control groups were significantly higher than those in experimental groups. CONCLUSIONS: In all experimental groups except group 6 (80 s, high intensity, lingual), shear bond strength was below the clinically accepted values. In clinical limitations where light curing from the same side of the bracket is not possible, doubling the curing time and increasing the light intensity during trans-illumination are recommended for achieving acceptable bond strengths.