Effect of Low-Level Laser Therapy on Patients With Class II Mandibular Deficiency Treated with Farmand Functional Appliance.

Introduction: Considering the positive effects of a low-level laser on new bone formation, we aimed to investigate the effects of a low-level laser in the treatment of patients with class II mandibular deficiency treated with Farmand functional appliance. Methods: Twenty-two growing patients aged 10-14 years were randomly divided into "Farmand" and "Farmand+Laser" groups. All patients were treated with Farmand functional appliance. Patients in the "Farmand+laser" group were exposed to laser irradiation (980 nm, 100 mw, 4 points around temporomandibular joints, 100 seconds each point) weekly for three months after 3-4 weeks of using the appliance. Lateral cephalometry radiographs were taken from all patients before and after the treatment period, and changes in skeletal and dental parameters were measured. Results: The association of the particular laser irradiation with the functional appliance led to a greater increase in the effective length of the mandible (Co-Gn, P=0.048), the anterior sagittal position of the mandible (SNB, P=0.029), and the length of the ramus (Co-Go, P=0.028), and it showed a further decrease in the discrepancy between the jaws (ANB, P=0.000) compared with the functional appliance alone. Conclusion: The application of the laser with the chosen parameters and protocol in conjunction with the functional appliance improved the effects of the functional appliance and reduced the discrepancy between the two jaws.

Evaluation of the effect of two types of laser on the growth of streptococcus mutans.

BACKGROUND AND AIMS: This study was done to compare the antibacterial effect of Photodynamic therapy (PDT) on streptococcus mutans (S. mutans) using two different light sources and photosensitizers (PS). MATERIALS AND METHODS: Five groups were studied in this research:no light and no toluidine blue ortho (TBO) as PS for control group, irradiation only (CO2 laser or Nd:YAG laser), and irradiation with PS (CO2 laser and TBO or Nd:YAG laser and TBO). Standard suspensions of S. mutans, based on the type of group, were used in different PDTs. Bacterial suspension from each treatment was subcultured onto the surface of Mueller-Hinton agar plates, and bacterial growth was assessed. The results were analyzed by analysis of variance (ANOVA). RESULTS: There was a statistically significant reduction in the viability of S. mutans in TBO with CO2 laser and TBO with Nd:YAG laser groups (p value < 0.05). However, there was no significant difference between control and groups treated with lasers only. The highest number of the colonies of S. mutans in treated groups was observed in CO2 laser irradiation only and the lowest number was seen in CO2 laser with TBO. In the groups irradiated alone (without TBO), no significant reduction of colonies was observed. There was no significant difference between the experimental groups. CONCLUSIONS: The colonies of S. mutans were susceptible to either CO2 laser or Nd:YAG laser in the presence of TBO with no significant difference. So these lasers with this photosensitizer may be useful in prevention of dental caries and antimicrobial treatment protocols.

Efficacy of erbium-doped yttrium aluminum garnet laser with casein phosphopeptide amorphous calcium phosphate with and without fluoride for remineralization of white spot lesions around orthodontic brackets.

OBJECTIVE: This study aimed to assess the efficacy of erbium-doped yttrium aluminum garnet (Er:YAG) laser, pastes containing casein phosphopeptide amorphous calcium phosphate (CPP-ACP) with and without fluoride and their combination for prevention of white spot lesions in the enamel. MATERIALS AND METHODS: This in vitro experimental study was conducted on 90 extracted sound premolars. The teeth were then randomly divided into six groups of 15: (1) Control, (2) laser, (3) CPP-ACP with fluoride (GC MI Paste, Recaldent™ 900 ppm as NaF), (4) CPP-ACP without fluoride (GC Tooth Mousse Recaldent™), (5) laser + CPP-ACP with fluoride, and (6) laser + CPP-ACP without fluoride. In each group, enamel surface was exposed to the remineralizing agent. The teeth were then subjected to pH cycling for 14 days. The teeth were then sectioned, polished, and underwent cross-sectional microhardness testing at 20-160 µ depth quantitatively. Using the Simpson's rule, the amount of mineral loss was calculated in each group. Statistical Analysis Used: ANOVA was used for the comparisons, and Tukey's test was applied for pairwise comparisons. RESULTS: The highest mean volume percentage of microhardness at 20-60 µ depth belonged to the group laser + CPP-ACP with fluoride and the lowest belonged to the control group (P = 0.001). The differences were not significant at 80-120 µ depth (P > 0.05). These finding are confirmed according to △Z (mineral loss). CONCLUSION: Based on these results, Er: YAG laser was able to decrease demineralization and was a potential alternative to preventive dentistry and was more effective when combined with CPP-ACP products.

Evaluation of the effect of three mouthwashes on the mechanical properties and surface morphology of several orthodontic wires: An in vitro study.

BACKGROUND: The aim of this study was to evaluate and compare the changes in the mechanical properties and surface morphology of different orthodontic wires after immersion in three mouthwash solutions. MATERIALS AND METHODS: In this in vitro study, five specimens of each of 0.016 inch nickel titanium (NiTi), coated NiTi, and stainless steel orthodontic wires were selected. The specimens were immersed in 0.05% sodium fluoride (NaF), 0.2% chlorhexidine, Zataria multiflora extract, and distilled water (control) for 1.5 h at 37°C. After immersion, loading and unloading forces at 0.5 mm intervals and the elastic modulus (E) of the wires were measured using a three-point bending test. Surface changes were observed with a scanning electron microscope (SEM). Two-way analysis of variance and Bonferroni tests were used to compare the properties of the wires. The level of significance was set at 0.05. RESULTS: Statistically significant changes in loading and unloading forces and E of the orthodontic wires were observed after immersion in different mouthwash solutions (P < 0.05). A pairwise comparison showed a nonsignificant difference between the effect of different mouthwashes on the E of different types of wires (P > 0.05). SEM images showed surface changes in some types ofthe orthodontic wires. CONCLUSION: The mouthwashes used in this study seemed to change the mechanical properties and surface quality of the orthodontic wires.

Effect of Methylphenidate on Orthodontic Tooth Movement and Histological Features of Bone Tissue in Rats: An Experimental Study.

INTRODUCTION: Methylphenidate is a psychostimulant drug, which is commonly used by children and teenagers. This age group receives most orthodontic treatment. Effect of this drug on tooth movement is unknown. AIM: The aim of this study was to evaluate the effect of methylphenidate on orthodontic tooth movement and histological features of bone tissue in rats. MATERIALS AND METHODS: Forty-two Wistar rats (male) were selected and divided to three groups, randomly (n=14). The control group (Group 1) received no drug, the experimental Group 2 received a constant dose of methylphenidate daily for 14 days while the experimental Group 3 received increasing doses of methylphenidate daily. To exert force, a NiTi coil spring was placed between the maxillary right first molar and the maxillary right central incisor. At the end of the study period, the amount of tooth movement was measured and then the rats were sacrificed for histological analysis of bone tissue. Differences between the experimental groups were analysed using Kruskal-wallis and Mann-Whitney U tests. RESULTS: No significant differences were found in the amount of orthodontic tooth movement or osteoclasts and lacunae, between the experimental groups (p>0.05). Mann-Whitney U analysis showed significant differences in the depth of resorption lacuna between Group 2 and 3 (p=0.037). CONCLUSION: Methylphenidate has no significant effect on orthodontic tooth movement or histological features of bone tissue in rats.

Effect of Er:YAG Laser and Sandblasting in Recycling of Ceramic Brackets.

Introduction: This study was performed to determine the shear bond strength of rebonded mechanically retentive ceramic brackets after recycling with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser or sandblasting. Methods: Twenty-eight debonded ceramic brackets plus 14 intact new ceramic brackets were used in this study. Debonded brackets were randomly divided into 2 groups of 14. One group was treated by Er:YAG laser and the other with sandblasting. All the specimens were randomly bonded to 42 intact human upper premolars. The shear bond strength of all specimens was determined with a universal testing machine at a crosshead speed of 0.5 mm/min until bond failure occurred. The recycled bracket base surfaces were observed under a scanning electron microscope (SEM). Analysis of variance (ANOVA) and Tukey tests were used to compare the shear bond strength of the 3 groups. Fisher exact test was used to evaluate the differences in adhesive remnant index (ARI) scores. Results: The highest bond strength belonged to brackets recycled by Sandblasting (16.83 MPa). There was no significant difference between the shear bond strength of laser and control groups. SEM photographs showed differences in 2 recycling methods. The laser recycled bracket appeared to have as well-cleaned base as the new bracket. Although the sandblasted bracket photographs showed no remnant adhesives, remarkable micro-roughening of the base of the bracket was apparent. Conclusion: According to the results of this study, both Er:YAG laser and sandblasting were efficient to mechanically recondition retentive ceramic brackets. Also, Er:YAG laser did not change the design of bracket base while removing the remnant adhesives which might encourage its application in clinical practice.

Effect of Carbon Dioxide Laser on Increasing Vestibular Depth in Cleft Lip and Palate Patients.

BACKGROUND: Shallow upper buccal sulcus deformity in cleft lip and palate patients is one of the common secondary deformities after primary cleft lip and palate repair; this deformity may prevent or complicate orthodontic and prosthodontic procedures causing aesthetic and functional problems. A number of methods are described to increase the anterior maxillary sulcus in these patients. PURPOSE: This study assessed the use of a carbon dioxide laser (CO2) to increase the sulcus depth. METHOD: Fifteen patients with cleft lip and palate (eight unilateral and seven bilateral) were studied. The surgical procedure was performed using CO2 laser. The vestibular depth and lip length were measured at three time points namely before surgery (T0), 1 week following surgery (T1), and 4 months following surgery (T2). After data collection, statistical analyses were done using PASW® version 18 SPSS. RESULTS: The mean values of vestibular depth were 9.46 ± 1.92, 13.83 ± 1.88, and 13.23 ± 1.76 mm for T0, T1, and T2, respectively. The vestibular depth significantly increased after 4 months of follow-up (p = 0.001). The mean amount of vestibular depth gain was not significantly different in unilateral and bilateral cleft groups (p = 0.908). The mean value of upper lip length increased by a mean of 1.23 mm and was statistically significant (p = 0.001). CONCLUSIONS: Upper buccal sulcus reconstruction with CO2 laser provides successful and stable results. CO2 laser application is suggested as an alternative to conventional vestibuloplasty.

Clinical and Radiographic Features of Pycnodysostosis with Emphasis on Dentofacial Problems.

Pycnodysostosis (PDO) is a rare genetic disorder characterized by cathepsin K deficiency which plays an important role in bone metabolism. Among clinical features of this disease which are mainly caused by altered bone remodeling are craniofacial abnormalities such as hypoplastic maxilla and obtuse gonial angle which consequently lead to respiratory insufficiency in forms of pharyngeal narrowing and severe snoring. In this paper, another case of this rare disorder is presented along with a review on etiology and management issues of respiratory insufficiency in these patients.

Effect of Four Methods of Surface Treatment on Shear Bond Strength of Orthodontic Brackets to Zirconium.

OBJECTIVES: Providing reliable attachment between bracket base and zirconia surface is a prerequisite for exertion of orthodontic force. The purpose of the present study was to evaluate the effect of four zirconium surface treatment methods on shear bond strength (SBS) of orthodontic brackets. MATERIALS AND METHODS: One block of zirconium was trimmed into four zirconium surfaces, which served as our four study groups and each had 18 metal brackets bonded to them. Once the glazed layer was removed, the first group was etched with 9.6% hydrofluoric acid (HF), and the remaining three groups were prepared by means of sandblasting and 1W, and 2W Er: YAG laser, respectively. After application of silane, central incisor brackets were bonded to the zirconium surfaces. The SBS values were measured by a Dartec testing machine with a crosshead speed of 1 mm/min. Data were analyzed using one-way ANOVA and Tukey's HSD for multiple comparisons. RESULTS: The highest SBS was achieved in the sandblasted group (7.81±1.02 MPa) followed in a descending order by 2W laser group (6.95±0.87 MPa), 1W laser group (6.87±0.92 MPa) and HF acid etched group (5.84±0.78 MPa). The differences between the study groups were statistically significant except between the laser groups (P<0.05). CONCLUSION: In terms of higher bond strength and safety, sandblasting and Er: YAG laser irradiation with power output of 1W and 2W can be considered more appropriate alternatives to HF acid etching for zirconium surface treatment prior to bracket bonding.

Antimicrobial effect of zataria multiflora extract in comparison with chlorhexidine mouthwash on experimentally contaminated orthodontic elastomeric ligatures.

OBJECTIVES: Long-term use of orthodontic appliances and fixation ligatures creates a favorable environment for the accumulation of oral normal microflora and increases the risk of enamel demineralization and periodontal disease. The aim of this study was to compare the antimicrobial effects of Zataria Multiflora extract and 0.2% chlorhexidine (CHX) mouthwash on experimentally contaminated orthodontic elastomeric ligatures. MATERIALS AND METHODS: In this lab trial study, Iranian and foreign-made elastomeric ligatures were experimentally contaminated in Streptococcus mutans, Enterococcus faecalis and Candida albicans suspensions. Ligatures were then decontaminated using 0.2% CHX as the control, 0.5 mg/ml Zataria multiflora extract mouthwashes as the test and phosphate buffered saline (PBS) as the negative control for one hour. Antimicrobial properties of both solutions were evaluated by comparing the mean viable bacterial cell count on both rings after decontamination, using SPSS version 15 software. RESULTS: The mean viable bacterial cell count on Iranian ligatures was greater than that on foreign-made ligatures before disinfection (P=0.001), however this difference for C. albicans was not statistically significant (P=0.061). Chlorhexidine mouthwash completely eliminated all tested microorganisms attached to both elastomeric rings, but Zataria extract was only capable of completely eliminating C. albicans from both ligatures. Statistically significant differences were found in viable bacterial counts on both ligatures before and after disinfection with Zataria extract (P=0.0001). CONCLUSION: Zataria multiflora extract has antimicrobial properties and can be used for disinfection of elastomeric ligatures. In vivo studies are required to evaluate the efficacy of the incorporation of this herbal extract in mouthwashes for orthodontic patients.

Effects of removing adhesive from tooth surfaces by Er:YAG laser and a composite bur on enamel surface roughnessand pulp chamber temperature.

BACKGROUND: At the end of fixed orthodontic treatment, the remnant of adhesive should be eliminated from the tooth surface. The purpose of this study was to compare the effect of three methods of removing adhesive on enamel surface roughness, dental pulp temperature, and also on the time spent. MATERIALS AND METHODS: The brackets on 90 extracted teeth were debonded using bracket removal pliers. A thermocouple sensor was fitted on the buccal wall of the pulp chamber through access cavity to measure thermal changes during adhesive removal. The residue of adhesive was eliminated from enamel surface of teeth by either tungsten carbide bur, erbium-doped yttrium aluminum garnet laser, or fiber reinforced composite bur. Scanning electron micrographs images were taken to assess the roughness of enamel surface. The time spent for adhesive removal was recorded as well. Chi-square test was used to evaluate the remnants of adhesive and enamel surface roughness; t-test and also repeated measurement analysis of variance were applied at P < 0.05 to compare the thermal changes of the pulp chamber and time spent between the methods of surface treatment. RESULTS: The results of surface roughness were significantly different (P < 0.001). The pulp temperature changed significantly (P < 0.001). Tungsten carbide bur increased the temperature by 5.5°C significantly slower than reinforced composite bur (P = 0.004), however removed the adhesive residue faster than two other methods although not significantly (P = 0.069). CONCLUSION: Within the limitations of this study, fiber reinforced composite bur created the smoothest enamel surface while Er:YAG laser the roughest. Tungsten carbide and composite burs generated more heat compared to Er:YAG laser. In addition, tungsten carbide bur was the fastest and Er:YAG laser the slowest devices to remove adhesive residue.

Load Deflection Characteristics of Nickel Titanium Initial Archwires.

OBJECTIVES: The aim of this study was to assess and compare the characteristics of commonly used initial archwires by their load deflection graphs. MATERIALS AND METHODS: This study tested three wire designs namely copper nickel titanium (CNT), nickel titanium (NiTi), and multi-strand NiTi (MSNT) archwires engaged in passive self-ligating (PSL) brackets, active self-ligating (ASL) brackets or conventional brackets. To evaluate the mechanical characteristics of the specimens, a three-point bending test was performed. The testing machine vertically applied force on the midpoint of the wire between the central incisor and canine teeth to obtain 2 and 4mm of deflection. The force level at maximum deflection and characteristics of plateau (the average plateau load and the plateau length) were recorded. Two-way ANOVA and Tukey's test were used at P <0.05 level of significance. RESULTS: Force level at maximum deflection and plateau length were significantly affected by the amount of deflection. The type of archwires and brackets had significant effects on force level at maximum deflection, and plateau length. However, the bracket type had no significant effect on the average plateau force. CONCLUSION: With any type of brackets in deflections of 2 and 4mm, MSNT wire exerted the lowest while NiTi wire exerted the highest force level at maximum deflection and plateau phase. The force level at maximum deflection and the plateau length increased with raising the amount of primary deflection; however the average plateau force did not change significantly.

Body dysmorphic disorder in Iranian orthodontic patients.

Patient's preoccupations with perceived defect in appearance or excessive concern about minimal flaws are among diagnostic criteria of body dysmorphic disorder (BDD). Sufferers usually seek cosmetic procedures such as orthodontic treatment. This study was conducted to estimate the prevalence of BDD among a sample of Iranian orthodontic patients. A total of 270 orthodontic patients were evaluated with BDD-YBOCS questionnaire for the diagnosis of BDD. Fifteen patients (5.5%) were screened positive for BDD. BDD was more frequent among females, singles and in younger patients. Most of the BDD patients experienced multiple previous orthodontic evaluations. The relative high prevalence of BDD among orthodontic patients in Iran offers that orthodontists should take psychologically based problems such as BDD into account while evaluating patient's orthodontic problems.

Effects of carbonated soft drink consumption on orthodontic tooth movements in rats.

OBJECTIVE: The aim of this animal study was to evaluate the possible effects of Carbonated Soft Drink consumption on the rate of orthodontic tooth movement in rats. MATERIALS AND METHODS: Thirty-six adult male Sprague-Dawley rats were randomly divided into two experimental groups and one control group. In the experimental groups (A&B), the water in the dietary regimen was replaced with soft drinks (Fanta® in group A and Cola® in group B) two weeks before placement of orthodontic appliances. Then 5-mm nickel-titanium closed-coil springs were placed between the maxillary right first molars and first incisors under general anesthesia. This regimen continued for two weeks more and animals drank soft drink ad libitum. At the end of the experimental period, the rats were sacrificed, and interproximal tooth movements were measured. RESULTS: The mean amounts of tooth movement were 0.19mm in group A, 0.22mm in group B and 0.37mm in group C. Statistical analysis with analysis of variance (ANOVA) test showed significant differences between all groups. The least movement occurred in group A that had received Fanta® drink. CONCLUSION: CSDs consumption decreases the rate of orthodontic tooth movement. The role of soft drinks in decreasing tooth movement might be related to its effects on bone metabolism.

Combined effects of Er: YAG laser and casein phosphopeptide-amorphous calcium phosphate on the inhibition of enamel demineralization: An in vitro study.

BACKGROUND: Development of white spot lesions on enamel is a significant and common problem during the fixed orthodontic treatment. Various preventive methods have been suggested. The purpose of this study was to evaluate the preventive potential of MI Paste Plus, Er: YAG Laser and combined under similar in vitro conditions against demineralization. MATERIALS AND METHODS: In this experimental in vitro study, 60 extracted premolars were randomly allocated to four groups (n = 15) of control, MI Paste Plus, Laser and MI + Laser (MIL). Enamel surface of each group was treated with one of above materials before and during the pH cycling for 12 days through a daily procedure of demineralization and remineralization for 3 h and 20 h, respectively. Teeth were sectioned and evaluated quantitatively by cross-sectional microhardness testing at 20 µm intervals from the outer enamel surface toward dentinoenamel junction up to 160 µm and data were analyzed using the one-way analysis of variance and Tukey test. P < 0.05 was considered as significant. RESULTS: MIL group had the least amount of demineralization (P < 0.001). Control group (C group) had the greatest relative mineral loss and the laser group (L group) had 45% less mineral loss than the C group and there was no significant difference between the MI Paste Plus and L group (P = 0.154). CONCLUSION: BASED ON THESE RESULTS, ER: YAG laser was able to decrease demineralization and was a potential alternative to preventive dentistry and was more effective when combined with casein phosphopeptide-amorphous calcium phosphate products.

Effect of tramadol at different doses on orthodontic tooth movement and bone resorption in rats.

BACKGROUND: Tramadol is an opioid agonist that has the potential of being abused. The aim of this study was to compare the effect of different doses of tramadol on orthodontic tooth movement (OTM) and bone resorption in rats. MATERIALS AND METHODS: Forty-two male rats were assigned randomly to two experimental groups and one control group. Nickel-titanium coil springs were used to exert orthodontic force. The rats in the control group and experimental group-1, respectively, received a daily injection of 0.1 ml of normal saline and 10 mg/kg of tramadol for 14 days. The rats in experimental group-2 received 10 mg/kg of the same drug on days 1-4, 20 mg/kg on days 5-8, 40 mg/kg on days 9-12 and 60 mg/kg on days 13 and 14. OTM was measured on days 4, 8, 12, and 14. At the end of the experimental period, the rats were sacrificed. Histological analysis was also performed to evaluate the number of osteoclasts, osteoblasts, and Howship's lacunae. RESULTS: Statistical analysis with analysis of variance tests showed that the rats in experimental group-2 had significantly decreased OTM compared with the other two groups (P < 0.05), whereas OTM for the rats in experimental group-1 was comparable to that in the control group (P > 0.05). The histological evaluations did not show any significant difference among the groups (P > 0.05). CONCLUSION: The effect of tramadol hydrochloride on OTM depends on the dosage used. High doses of the drug reduce the extent of OTM significantly.

Shear bond strength of orthodontic brackets bonded to porcelain following etching with Er:YAG laser versus hydrofluoric acid.

AIM: The purpose of the present study was to evaluate the shear bond strength of orthodontic brackets bonded to porcelain following etching with erbium-doped yttrium aluminum garnet (Er:YAG) laser compared with 9.6% hydrofluoric acid (HF). METHODS: A total of 100 porcelain disk samples were divided into four groups, and after removing their glazed layer, the first group was etched with 9.6% HF, and the other three groups were etched with Er:YAG lasers of 1.6, 2, and 3.2 W, respectively. After application of silane on the disk surfaces, central incisor brackets were bonded with composite on the disks. The disks were mounted on an acrylic stand for measuring the shear bond strengths. The shear bond strengths were measured by a testing machine. RESULTS: The mean shear bond strength in the laser group with power of 1.6 W (7.88 MPa) was more than that of the HF (7.4MPa), 2-W power (7.52 MPa), and 3.2-W power (7.45 MPa) groups, but this difference was not statistically significant. Examination with an electron microscope showed different patterns of etching by HF and laser. Also, etching by laser and HF had not resulted in cracks on the porcelain surface. CONCLUSION: Er:YAG laser can be a suitable method for bonding of orthodontic brackets to porcelain surfaces.

Hereditary gingival fibromatosis: a review and a report of a rare case.

Hereditary gingival fibromatosis (HGF) is a rare condition which manifests itself by an enlarged gingival tissue covering teeth to various extents. The condition may occur isolated or as part of a syndrome. This paper presents a case of 9-year-old female patient suffering from HGF with chief complaint of mouth protrusion. Cephalometric findings showed severe mandibular deficiency and vertical maxillary excess. Patient exhibited perioral muscle contraction on mouth closing. After discussing the treatment possibilities with the patient and her parents, the decision was made to wait until growth potential decreases (following the adolescent growth spurt) and to correct the problem with orthognathic surgery.

New regression equations for mixed dentition space analysis in an Iranian population.

AIMS: Prediction of the mesiodistal crown width of unerupted canines and premolars is an important aspect of mixed dentition analysis. The accuracy of Tanaka-Johnston equations, the most commonly method, is questionable when it is applied to different ethnic groups. In this study, we aimed to develop a new regression equation for this prediction in an Iranian population. MATERIALS AND METHODS: The dental casts of 120 Iranian subjects with complete permanent dentition were selected. Mesiodistal crown widths of teeth were measured with digital caliper. In the first part of the study, the correlation and linear regression equations between four mandibular incisors and the canine-premolars segments of both arches were developed (modified Tanaka-Johnston equation). In the second part, as a new method, correlation and linear regression equations were developed between the sum of mandibular central incisors-maxillary first molars and the canine-premolars segments. RESULTS: It was found that the correlation coefficients between the sum of mandibular central incisors-maxillary first molars and the maxillary and mandibular canine-premolars segments were higher (r = 0.66, 0.68 respectively) than the one between the four mandibular incisors and the canine-premolars segments (r = 0.58. 0.64). CONCLUSION: New linear regression equations were derived. In this study, the sum of mandibular central incisors and maxillary first molars was better predictor for unerupted canines and premolars. This novel approach allows the prediction of width of unerupted canines and premolars to take place at earlier age. CLINICAL SIGNIFICANCE: Using the new method, orthodontists could take advantage of mixed dentition analysis at earlier age. Moreover, to test the derived equations on a larger sample size and in other ethnicities is highly recommended.

Effect of direct electric current on parietal bone osteogenesis.

INTRODUCTION: It has been shown that biphasic electric stimuli may be effective in stimulation of bone growth. This study aimed to evaluate the role of direct electric current on osteogenesis of the parietal bone in a canine model. MATERIALS AND METHODS: After surgical implantation of assembly involving 3 electrodes in the parietal bones in 5 adult male dogs, 20-MA direct electric current was applied. As a control group, a neutral assembly was implanted on the contralateral side of the calvaria.After 45 days of implantation, through a second surgical procedure, the bone samples were taken off the implantation sites and subjected to histologic evaluation. The data were analyzed with SPSS 16 software package (SPSS Inc., Chicago, IL) using Chi-squared and Fisher exact tests. RESULTS: The bony tissues from all tissue sample sites were viable. Foreign body reaction that was documented by the presence of giant cells was observed in all samples. Histologic evaluation of samples revealed no statistically significant difference with respect to inflammatory reaction, bony trabecular thickness, bone arrangement, and maturation among the 3 electrode types (P > 0.05). CONCLUSIONS: Direct electric stimulation of the parietal bone in this canine model revealed no statistically significant difference with respect to inflammatory reaction, bony trabecular thickness, bone arrangement, and maturation.