Abstract: Aims: This study investigated the effect of two home- bleaching regimens (7.5% hydrogen peroxide, 16% carbamide peroxide) on the color change and microhardness of microhybrid composite (Compo-san) and hybrid composite (TetricCeram) and RMGIC (Vivaglass). Materials and Methods: Thirty six disk – shaped specimens (5 × 2 mm)(of each restorative material for each test) were prepared and di-vided into three subgroup (n = 12).An unbleached group was used as control, while the remaining spec-imens in the two subgroups were bleached with bleaching regimens . Color change was assessed by using Vita Easy shade device , and the microhardness was determined by a Vicker,s microhardness tester. Means values were compared statistically with one way analysis of variance (ANOVA) followed by Duncan's Multiple Rang Test to determine the significant differences among the tested groups at (p = ≤ 0.05 )level of significance. Results: TetricCeram displayed unacceptable color change after bleach-ing with(16% carbamide peroxide) bleaching regimen. Decreasing in microhardness of Vivaglass after bleaching regimens, and microhardness of Composan after16% carbamide peroxide. Conclusion: The 16% carbamide peroxide bleaching regimen has significant effects on color change of TetricCeram and decreasing microhardness of Vivaglass and Composan restorative materials.

Abstract: Aims: To 1. Assess the horizontal lip position and lip thickness in both Class I and Class II Division 1 subjects; 2. To investigate the effect of gender on the horizontal lip position and lip thickness; 3. To identify the effect of skeletal differences on lip position and thickness. Materials and Methods: The sample consisted of 60 cephalometric radiographs of 30 dental and skeletal Class I subjects (15 males, 15 females) and 30 dental and skeletal Class II Division 1 subjects (15 males, 15 females). The hori-zontal lip position and thickness was analyzed using 11 linear and 4 angular measurements. Using SPSS software package (version 11.5), descriptive statistics and independent sample t–test were meas-ured to compare between the two Classes and two genders. The differences were considered significant at p < 0.05. Results: In Class I no significant differences were noticed in most of the variables except in upper lip (Ls) to Steiner line and lower lip (Li) to Holdaway line where females showed more retruded position and larger nasolabial angle (NLA) when compared to males. In Class II Division 1 subjects, the upper and lower lips were significantly protrusive in males when compared with females in relation to Sushner line (S2). Class II Division 1 males showed more protruded upper and lower lips in relation to S2 line, significantly smaller Z angle and higher H angle when compared with Class I males. Comparison between Class I and Class II Division 1 females showed a significantly higher val-ue of upper lip in relation to Steiner line (S1), and significantly smaller upper and lower lips in relation to E line, smaller Z angle and larger H angle. Conclusions: Some of the variables were not affected neither by gender nor by skeletal base while other showed statistically significant differences following gender or skeletal Class or both. However, the effect of skeletal base difference was more obvious as higher number of significant differences were seen between the two Classes

Abstract: Aims: To investigate the effect of the thickness of relining material, curing method (water bath or mi-crowave), and the surface treatment by methyl methacrylate on transverse and tensile strength of re-lined acrylic resin denture base. Materials and methods: A pilot study was done by preparing 65 sam-ples to evaluate the effect of the thickness of relining material in relation to denture base on the trans-verse strength of acrylic resin denture base, and to study the effect of surface treatment by methyl methacrylate on the transverse strength of acrylic resin denture base. The main study was done by pre-paring 320 samples and divided into two parts to study the mechanical properties of samples represent-ing a denture base cured by water bath and other group cured by microwave curing technique, and then the effect of relining by the two curing methods and the effect of surface treatment were evaluated. Analysis of variance (ANOVA) and Duncan's multiple range tests were used for statistical analysis. Results: of this study showed that the different thickness of relining material in relation to denture base had no significant difference on the transverse strength of the relined denture base. The transverse strength and tensile bonding strength of the relined samples were significantly improved (P=0.05) by monomer surface treatment for 180 seconds. Conclusions: Transverse and tensile strength of the acryl-ic resin denture base were affected by relining. Microwave curing method gave better mechanical properties of the relined acrylic resin denture base.

Abstract: Aims: To investigate the effect of relining by using two curing methods (water bath, or microwave) on some properties ( surface hardness, color property, residual monomer, and porosity) of relined acrylic resin denture base. Materials and methods: The study was done by preparing 320 samples, divided into two parts, the first part involved studying surface hardness, color property, residual monomer, and porosity of samples representing a denture base cured by water bath curing method, and the samples of second part cured by microwave curing method, then the effect of relining by the two curing methods (water bath, and microwave) were evaluated. Samples with dimensions of 30×15×3 ± 0.03mm for the indentation hardness test, 45×10×2.5mm for the color property test, 20×20×3mm for residual monomer test were prepared in this study. Analysis of variance (ANOVA) and Duncan's multiple range tests were used for statistical analysis. Results: surface hardness of denture base cured by microwave was significantly higher (at P=0.05) than denture base cured by water bath, all the relined samples has sig-nificant higher absorbance, and showed that the elusion of monomer was higher at the 1st day. Conclu-sions: Surface hardness, color property and residual monomer of the acrylic resin denture base were affected by relining. Microwave curing method gave better mechanical, and physical properties of the relined acrylic resin denture base, the amount of residual monomer was less in the microwave curing method. Both curing methods gave samples free from porosities.

Abstract: Aim: To evaluate the surface roughness of three different types of light activated composite resin using (Sof-Lex) – polishing system, a profilometer study. Materials and Methods: A total of 30 resin com-posite disks were prepared from three different types of composite resin include 3 – groups. Group I: 10 specimens were prepared from light activated nano hybride (Tetric n – Ceram, Ivoclar – Vivadent – Liechtenstein). Group II: 10 specimens were prepared from light activated microhybride composite resin (Arabesk – Voco, Germany). Group III: 10 specimens were prepared from light activated poly-glas composite resin (Solitaire – 2, Heraeus, Kulzer, Germany). The resin blocks finished and polished using (Sof – Lex) polishing system. The specimens were analyzed for surface roughness using “Pro-filometer”. Results: Tetric n – Ceram composite resin showed the lowest roughness average (0.112 μm) followed by Arabesk composite (0.150 μm), Solitaire – 2 composite resin showed the highest roughness average (0.341 μm). Conclusions: Tetric n– Ceram (nano-hybride) was the best polished composite resin, showed the least roughness average.

Abstract: Aims: To evaluate and compare the antibacterial effect of three types of dentin bonding agents. Also, to evaluate the antibacterial effect after different time intervals (24, 48, and 72) hs. Materials and Methods: Materials tested in this study were G bond, Single bond (SB), and Excite bond. Tested mi-croorganisms were Enterococcus faecalis (E. faecalis) and Streptococcus mutans (S. mutans). The antibacterial activity were investigated by agar diffusion test performed with adhesives cured on the surface of dentin discs. Also, the antibacterial effect were investigated by evaluation of growth inhibi-tion after 24, 48, and 72 hrs microplate direct contact test using spectrophotometer. The data were ana-lyzed statistically using one way ANOVA and Tukeyʼs test. Results: G bond had antibacterial effect by the two tests and against the two examined bacteria significantly higher than SB and Excite, also SB significantly had antibacterial effect better than Excite bond. The result also revealed that antibac-terial effect of SB and Excite Bond significantly decreased by the time while G bond was not signifi-cantly decrease. Conclusions: Under the limitation of the present study, it is concluded that G bond is able to delay bacterial growth during restorative treatment of dental caries

Abstract: Aim: The aim of the study is to evaluate the efficacy of three dentures cleanser on Candida related denture stomatitis through assessing their ability to reduce the number of colony forming unit (CFU) of Candida on palate of the patient for different times. Materials and methods: Group of 12 patients who have denture stomatitis were divided into four groups according to the type of denture cleaners (Protefix, sodium hypochlorite solution 0.02%, saturated sodium chloride salt solution and control wa-ter). The microbiological examination was done to determine the efficacy of the cleansers that used by assessing the number of (CFU) at different times (day before treatment and after 14, 28days of treat-ment). The data were statistically analyzed, (ANOVA) followed by Duncan's multiple Range test to assess the significant difference between the groups at P≤0.05. Results: The results showed that there was a significant effect of three cleansers on reducing number of (CFU) of Candida species in the treatment of denture stomatitis after 14 and 28 days of treatment, but it was not significant for control water group. Sodium hypochlorite showed the highest efficacy. Conclusions: Result showed that there was no significant difference in the efficacy between the three cleansers indicating that all cleansers are effective in the treatment of denture stomatitis .

Abstract: Aims: To determine the trends of the two major dental diseases (dental caries and periodontal disease) in a group of 13-15 year old intermediate school and their treatment needs. Materials and Methods: A total of 516 intermediate school students were examined. Dental caries and treatment needs were as-sessed according to the WHO 1997 guidelines. The assessment of the gingival health and treatment needs of the students was performed using the CPITN index as recommended by the WHO 1987. Six index teeth were examined and the presence of gingival bleeding and calculus was recorded. Results: Dental caries in the sample has increased with a mean of 5.17. Dental caries increased with age with a statistically significant age difference. Females tended to have a higher DMFT of 5.5 compared to males 4.79 with significant difference, only 6.6% of the sample was caries free. The majority of the samples needed one surface fillings with a mean of 3.6/child. Other dental treatments were needed to a lesser extent. Regarding the periodontal status, the disease was present in 97.5% of the sample, there was no significant age difference regarding periodontal health. Females tended to have a healthier gin-giva compared to males with significant difference. Regarding periodontal treatment needs, 97.5% of the sample required dental health education, while 65.9 % required professional scaling and polishing. Conclusions: To improve children’s oral health, community school-based oral health educational pro-grams should be established starting from primary and extending to intermediate schools, stressing on sugar restriction and oral hygiene measures, fluorides and fissure sealants can effectively be used too.

Abstract: Aims: The present study aimed to determine stress and strain distribution on the four lower incisors under the effect of (400g) calculated retracted orthodontic force. Materials and methods: Using finite element analysis method, frictionless retraction technique was successfully used with the aid of continuous (delta loop) on NiTi, Stainless steel wires without gable bends and stainless steel looped wire using 40°. gable bends(20° alpha, 20° beta gable) respectively. Results: High compressive stress concentration in labiolingual direction are observed near the point of force application and along the line of action of orthodontic wire at the crown of both lateral and central incisors. Conclusions: The stress distribution is not the same for the all retracted segment and there was independent movement of lateral incisors from the central incisors except for the retraction using NiTi wires which exhibits uniform movements for both lateral and central incisors.

Abstract: Aims: This report describes a case of eleven years old female with impacted maxillary central incisors and presence of two supernumerary teeth .The surgical exposure and orthodontic traction of bilaterally impacted central incisors after removal of impacted supernumerary teeth is presented in this report. Materials and Methods: Clinical, radiographic follow-up and treatment was conducted at the department of orthodontic and maxillofacial surgery in the college of dentistry ,mosul university .The surgical removal of supernumerary teeth done then surgical exposure and orthodontic traction done. Results: The impacted maxillary central in-cisors were successfully positioned and presented an acceptable gingival contour after treat-ment. Conclusion: Maxillary permanent central incisors were successfully positioned in the maxillary arch by surgical exposure and orthodontic traction, which showed good stability.

Abstract: Aims: To evaluate the regional bond strength of four resin-based luting cements to post space dentin after irrigating with different irrigant solutions regimens. Materials and Methods: Eighty extracted human lower premolars were decoronated, instrumented, and obturated. Post space was prepared in each root, then randomly divided into four groups (n=20) according to the final irrigation regimen for the post space, Gp.1: distilled water (DW) control; Gp.2: 5.25% NaOCl+DW; Gp.3: 17%EDTA+DW; Gp.4: 5.25%NaOCl+17% EDTA+DW. Each group was further subdivided into four subgroups (n=5) according to the luting cements, Gp.(1,2,3,4)A (Vivaglass®Liner); Gp.(1,2,3,4)B (PermaCem®-Dual); Gp.(1,2,3,4)C (Variolink II); Gp.(1,2,3,4) D (LuxaCore®Z-Dual), then each post-space was sectioned horizontally into three slices. A push-out test was performed to measure regional bond strengths and the fracture modes was evaluated using a stereomicroscope. Results: The use of 5.25% NaOCl+17% EDTA+DW result in higher bond strength than other treatments. While the control group gives the lowest. (LuxaCore®Z-Dual) showed the highest bond strength than other resin cements. (Vivaglass®Liner) gives the lowest bond strength. The regional bond strengths decreased significantly toward the apical third. The failure mode recorded was mostly adhesive in nature except for groups (3D,4D) showed some mixed failure at the coronal third. Conclusions: NaOCl+ EDTA flush had a profound effect on resin bond strength to radicular dentin. (LuxaCore®Z-Dual) composite core buildup material exhibited the higher regional bond strength to radicular dentin. The regional bond strength decreased from coronal to apical direction.

Abstract: Aims: To evaluate the effect of length and weight of 5–13 years old children on eruption of permanent teeth in Mosul City. Materials and Methods: The sample consisted of 894 children and teenagers; 412 males and 482 females ranging in age from 5–13 years. A tooth was defined as erupted when any part of its crown pierced its gingiva. The sample was divided into 4 age groups: Group 1: 250 child and teenager aged 5–

Abstract: Aims: The aims of present study were to compare shear bond strength (SBS) and push-out bond strength (PBS) of three types of sealers to gutta percha (G) and dentin (D) and to assess failure modes at debonded interfaces.  Materials and Methods: Sealers tested were AH Plus, Sealer 26, and Endofill. In PBS, 30 mandibular premolar decoronated and instrumented with rotary ProTaper to F3 then teeth were divided into 3 groups (10 teeth in each) and obturated with F3 proTaper G and one of tested sealer, 1mm mid root slices were prepared for PBS test. In SBS/D, 30 root cylinders 7 mm length were embedded horizontally in resin then root surfaces were flattened and smooth. In SBS/G, 30 G cylinders were embedded in a resin. In both SBS tests, specimens were divided into three groups, 10 samples each then polyethylene tubes positioned on polished specimens (prepared for SBS/D and SBS/G) filled with one of the tested sealer. All  BS tests were performed on digital universal testing machine. Collected data analyzed statistically using one way ANOVA and Tukey test. Results: PBS, SBS/D, and SBS/G for AH Plus significantly higher than Sealer 26 and Endofill. Also Sealer 26 exhibited significantly higher bond strength than Endofill. Predominance mode of failures were adhesive and mixed. Conclusions: According to the finding of present study, it can be concluded that the AH Plus for root canal therapy produce better results in endodontic. PBS and SBS were sufficient tests to measure bond strength of root canal sealers to G and D.

Abstract: Aims:  The aim of this study was to investigate the influence of different indirect veneering materials on the microhardness of dual-cured resin cements. Materials and Methods: Three disc specimens (2.0 mm height and 5mm diameter)were prepared from the following indirect restorative materials  (Indirect composite resin, Gardia-GC, JAPAN, Feldspathic porcelain VITA VIMK 95-Germany  and Zirconia veneer, VITA-Zahnfabrik, Germany).  Two dual cure resin cements were used ( Variolink II, Ivoclar Vivadent AG, Liechtenstein and Bis-Cem, Bisco-Schaumburg, USA). Twenty  specimens were prepared from each type of cement and divided into 4 groups, one as control and others as indirect restorative materials. After mixing cements were placed in a plastic mold (5mm diameter and 1mm height ) and light activated directly or through veneering discs for 30s using LED light at 500mW/cm2. Specimen subjected to three indentation using Vicker hardness tester with load of 50gm for 15 second. Data were statistically analyzed using ANOVA and independent t-test at (α= 0.05). Results: For both cements the control groups showed higher hardness value than other groups. Specimens cured through indirect resin composite shows the highest microhardness while those cured through Zirconia shows the lowest value. Variolink II resin cement demonstrated higher microhardness than Bis-Cem cement regardless of the curing condition. Conclusions: Type of indirect restorative veneering materials influence microhardness  of  resin cement luting agent

Abstract: Aims: Aim of the study to evaluate the effect of two different disinfection methods for two periods of time on surface roughness of soft denture lining materials (Vertex and Molloplast-B). Materials and methods : The effect of two disinfection methods ,first chemical disinfection method (which include  artificial saliva with saturated salt and artificial saliva with vinegar solution), and second microwave method on the surface roughness of soft denture lining materials for two periods of times (14 and 30 days) was evaluated, One hundred samples were prepared. ANOVA and Duncan,s multiple range test were performed to determine the significant difference among the tested groups at p ≤ 0.05% .Results: The results showed that the lowest value of surface roughness (Ra)value after 14 and 30 days for Vertex soft denture lining material was achieved with the microwave group, while the lowest value of surface roughness (Ra)value after 14 and 30 days for Molloplast-B was achieved with the distilled water. The highest value of surface roughness (Ra) for Vertex soft denture lining material was achieved with vinegar after 14 and 30 days., while for Molloplast-B was achieved with vinegar group after 14 days and with salt group after 30 days. Conclusion : The results of T-test Table showed that there were no statistically significant differences in surface roughness(Ra) value between Vertex and Molloplast -B soft denture lining materials after 14 and 30 days except for microwave group after 14 days at P value ≤ 0.05. Distilled water disinfection has less effect on the property than other chemical disinfection and microwave regimen. The effect of disinfection increase significantly with  increasing period of  time .

Abstract: Aims:To evaluate the relationship between some of facial parameters including [(alae of nose, mouth, philtrum of upper lip) widths with interzygomatic distance] and straight maxillary intercanine distance for clinical application advantage. Materials and Methods: In this clinical study, (140) dental students in College of Dentistry/University of Mosul were examined and their facial and dental measurements were taken directly from each student by using an electronic digital vernier caliper. The data were collected and analyzed with computer to determine the correlation between the studied factors.Result: The results of this study demonstrated that all the measured parameters were larger in males than females which being statistically different between the two sexes and the Pearson Product Moment Correlation Coefficient test revealed that non of the facial parameters were measured had a significant correlation with straight maxillary intercanine cusp tips distance in females, while both of interzygomatic distance and philtrum width of upper lip had a significant correlation with straight maxillary intercanine cusp tips distance in males which they could be used to determine this distance for replacement of maxillary anterior teeth in males. Conclusion: Depending on previously mentioned results the straight maxillary intercanine distance was equal to interzygomatic distance divided by a factor of( 3.3), while multiplying the width of the philtrum of upper lip with a factor of ( 2.75) gives us an estimation of the straight maxillary intercanine cusp tips distance.

Abstract: The mandibular asymmetry is important because of its direct effect on facial appearance. Aims: The aim of the present study was to determine the prevalence and severity of mandibular asymmetries between right and left sides. Materials and methods: The sample consisted of 22 males and 23 females having lateral cephalometric and orthopantomographic radiographs. Four linear and two angular measurements were compared between right and left sides of the mandible. These measurements were: ramus height(RH), ramus width(RW), corpus height(CH), corpus length(CL), gonial angle(Go) and condylar angle(Co). Results: The study revealed no significant differences between right and left sides of the mandible, in both gender, regarding the 4 linear  measurements. Whereas for the angular measurements there was a significant difference in condylar angle between right and left sides in both male and female groups. Also no significant gender differences were found regarding all measurements except in corpus height. Conclusion: No significant facial asymmetry was found between right and left sides of the mandible for the population being studied in both genders except in condylar angle. In addition it was found out that severe mandibular asymmetry is not so a common occurrence

Abstract: Aims: To determine whether obliquely inserted mini-implants can be loaded immediately with light orthodontic force? And which mini-implants are more stable those with 90 degree or 60 degree insertion angles? Materials and Methods: three rabbits were used in this study. Sixteen mini-implants divided into 2 groups equally. The first group implanted in the rabbit’s tibia bone at 90 degree insertion angle and the second group implanted in the rabbit’s tibia bone at 60 degree insertion angle. The stability of mini-implants was measured using periotest device immediately before and after loading and after 2 weeks of loading  period. The data were analyzed using descriptive statistic, Analysis of variance (ANOVA), Duncan Multiple analysis range test and student t-test. Result: mini-implants at 60 degree  insertion angle can be loaded immediately with light orthodontic force. Also, those miniimplants having a significant greater stability  before  loading and after two weeks of  loading period in comparison with mini-implants implanted at 90 degree angle. Conclusions: In clinical practice, miniimplants inclined to the bone surface at 60degree tend to have better primary stability and can be loaded immediately.

Abstract: Aims: The aims of this study were to evaluate the dental and skeletal parameters which might be associated with mandibular anterior crowding in the early mixed dentition and to determine if these parameters of patients with and without crowding differ. Materials and Methods: Study models and lateral cephalometric radiographs of 80 Iraqi children lived in the center of Mosul City (40 boys and 40 girls), were evaluated. The age ranged between 7-10 years .The casts were divided into two groups ; crowding and non crowding, the lengths and widths of the lower dental arches, dental and skeletal (linear and angular) cephalometric measurements were used to determine the effect of these measurements on mandibular anterior crowding. Results: Significant differences between crowding and non crowding groups were seen in many of dental and skeletal measurements particularly the angles measured the relation between the maxilla and mandible to the anterior cranial base, the length of the anterior and posterior cranial base and the angles measured the inclination of lower incisors to the mandibular plane. The correlation coefficients of the amount of crowding with all the measurements were studied. Some of them showed a positive  correlation , while others showed a negative one.  Conclusions: The current results suggested that besides tooth size and transverse arch dimensions, effective dentoskeletal measurements are also an important factors related to mandibular anterior crowding in the early mixed dentition.

Abstract: Aims: to evaluate the effectiveness of acupressure on Chengijiang (REN- 24) point in controlling of gag reflex in hypersensitive male and female patients attending for prosthetic treatment. Materials and Methods: Thirty patients complaining from gag reflex during prosthetic treatment were selected. Fifteen were males and fifteen were females. The gag duration of each patient according to Ellinger classification was scored before and after acupressure. Statistical analysis to the results using Mann-Wittni test was done. Results: This study showed significant differences in scores of gagged patients (both males and females) before and after acupressure (P < 0.005); while there were no significant differences between scores of male patients after acupressure and scores of female patients after acupressure.  Conclusion: Acupressure is a safe, quick, non invasive technique can be done by dentist or dental assistant to alleviate gag reflex of prosthetic patient.

Abstract: Aims: The purpose of this study is to explore the behavior of cold curing acrylic resin which used in dentistry during some mechanical properties (hardness, compression and impact)tests under different temperatures. Materials and Methods: Twenty four pinks from cold cured samples for each mechanical-physical properties tested were prepared under temperatures(20,24,28,32,37,45,50) C0 to cover a wide range similar to actual service temperatures. All specimens were soaked in distilled water. One hour ,two hours ,three hours were chosen as the time for soaking and the means of the tests were recorded. Results: The results show that the compression  and hardness decreasing with the increasing of  temperature and increase of impact strength with the increase of temperature up to (28) C0 then followed by a decrease in impact strength. Conclusions: The decrease of compressive strength and hardness is compatible with the results obtained under compressive Conditions. Keywords: Temperature, mechanical properties, cold cured material.   

Abstract: Aims: To evaluate the effect of different ligature types and ligation techniques on the rate of space closure, tipping and rotation of canine after sliding. Materials and Methods: The total number of the samples were 50 sample classified under five groups according to the method and type of ligation; the first group: preformed stainless steel ligature wire (SL), the second group: preformed stainless steel kobayashi ligature wire (KL), the third group: elastomeric ligature in figure – O (EO), the fourth group: elastomeric ligature in figure – 8 (E8) and the fifth group: non-conventional Slide Leone elastomeric ligature (NE). A typodont used in this study with preadjusted Roth stainless steel brackets 0.022×0.030 inch and a stainless steel orthodontic arch wire 0.017×0.025 inch. A bite plane extension bar (BPB) and canine extension bar (CB) are constructed for the measurement of canine tipping and rotation. A 180 gm. of force applied by short continuous elastomeric power chain to retract the right canine. After immersion of the typodont in water bathe with 50-55 0C for 5 minutes, the rate of space closure were measured in millimeter using vernier (from the distal wings of canine bracket and the mesial wings of the second premolar), the tipping and rotation were measured by taking a photograph to the typodont using digital camera, with transvers projection (for tipping) and occlusal projection (for rotation) from right side (directly toward the right canine), then the angle between (BPB) and (CB) measured directly on the photograph using Protractor. Results: A statistical analysis (descriptive statistics, ANOVA and Duncan Multiple Analysis Range Test) used in this study, for the rate of space closure the results showed that there is a significant difference between the five groups at p ≤ 0.001, the NE group had the highest amount of tooth movement while KL group had the lowest level, for the tipping; the NE group had the highest level of tipping while SL, KL and E8 groups had the lowest level with a non-significant difference between them, for the rotation; the  results showed that NE group had the highest level of rotation, while KL group had the lowest level. Conclusions: The higher rate of space closure, the higher rotational degree and the higher tipping degree were associated with NE group, while KL group had shown the lowest rate of space closure and the lowest rotational degree. The lowest degree of tipping was associated with the SL, KL and E8 groups.

Abstract: Aims: Evaluate the amount of anchorage loss of the lower posterior teeth 2nd premolar and first molar when used as anchorage teeth for retraction of canine bilaterally by using lace back technique after extraction of first premolar in sever crowding cases. Materials and Methods: Two groups of brackets, one of them labial (conventional) were bonded on the labial aspect of metal teeth except  4  4  typodont by special adhesive and other groups lingual brackets also bonded in the same teeth lingual surface and two types of light or low gauge arch wire Niti , twisted multi strand for sliding the canines retraction by using elastomeric ring with ligature  wire active lace back once with labial and other with lingual technique. Results: There is no significant difference between twisted multi strand wire when ligated on the teeth in both lingual technique and labial technique. Significant difference when used Niti wire on lingual technique when compared with the same type of wire when ligated on labial technique and significant difference with twisted multi strand when ligated on teeth in lingual technique. Conclusion: Anchorage loss decreases with twisted multi strand wire because the friction increased between arch wire and base of bracket in both labial and lingual technique and decreased with Niti wire specially when used in lingual techniques