Background and objective: Lithium disilicate widely used, and it is important to correctly bond orthodontic brackets to such materials. This study aimed to assess the impact of various types of surface conditioning methods on the shear bond strength (SBS) of orthodontic metal brackets to lithium disilicate crown.Materials and methods: In this in vitro study, 30 lithium disilicate specimens were prepared based on the type of surface conditioning into three surface conditioning groups (n=10 for each group). First group the semi-crowns surface was conditioned with 10% hydrofluoric acid etching, the second group was micro-etched with sandblast particles (50 um aluminum oxide particles) and the last group was conditioned with ultrasonic scaler. Valo light cure was utilized with 3200mw/cm2 light intensity. SBS was measured using a universal testing machine. The findings were statistically examined.Result: The results showed significant difference among the three groups where the sandblasting group had the higher mean of SBS, while the hydrofluoric acid etching group had the lower value and in between, the mean of ultra-sonic intermediate.Conclusions: Although the means of the three types of surface conditioning were significantly different, shear bond strength was positively affected by all of them and subsequently all types may be considered recommended techniques for reliable shear bond strength.

Aims:To validate Tanaka and Johnston's analysis on (50) Iraqi patients (29 females and 21 males) aged 14-22 years. The patients had normal class I molar relation ship with full permanent dentition. Materials and Methods: Plaster models of 50 (14-22) years old patients were selected. Mesio-distal crown diameter for maxillary and mandibular permanent teeth were measured. Statistical descriptive, probability theory, correlation coefficients between individual and grouped teeth were calculated using Tanaka and Johnston method. Results: Tanaka and Johnston's analysis tables, equations and approximations were modified in order to improve the accuracy of the prediction. The correlation coefficients found between the size of the permanent mandibular central incisors and maxillary first molars (1, 1, 6 and 6) and maxillary and mandibular canines and premolars were high (r = 0.62 and r = 0.67, respectively). New, more accurate prediction tables applicable at earlier ages, and new regression equations were constructed. In addition, new easier approximations were developed to allow the prediction of the size of the unerupted maxillary canines and premolars by adding 5.6 mm to the half-widths of teeth 1, 1, 6 and 6. The analogous prediction of the size of unerupted mandibular canines and premolars was obtained by adding 5.4 mm to the half widths of same teeth 1 ,1 , 6 and 6. Conclusions: The new analysis prediction tables and new regression equations based on teeth 1 ,1, 6 and 6, which erupt earlier than teeth used by Tanaka and Johnston, proved even more accurate than both previous equations.

Background and Objectives: Beautiful face proportions are likely to approximate the Divine proportion or golden ratio (1.618:1). This study set out to determine the facial proportions of adults from Duhok and to compare the findings to what are known as golden or divine proportions. Also, to assess the proportions of males and females who joined up in this study. Methods: 176 participants (88 females, 88 males) with well-balanced facial features and class I Angle's malocclusion were chosen and frontal photographs were taken for them. Facial proportion in height and width were assessed and compared in both genders. The facial golden proportion was established. Results: Based on the results, more deviation from golden ratios found in male faces than female faces. Male and female ratios were noticeably varied from one another and from other world's population. Conclusion: In comparison to the golden ratio, the population of Duhok has balance in facial soft-tissue. Nevertheless, some variables deviate somewhat from the golden ratio.

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Soft tissue chin, hard tissue chin, pogonion, digital cephalometric. he protrusive chin is a uniquely human trait, lacking in all other primates and in hominid aaaaaa ancestors (1) A harmonious soft tissue profile, an important treatment goal in orthodontics, is sometimes difficult to achieve, partly because the soft tissue overlying the teeth and bones is highly variable in its thickness. (2) Orthodontic treatment improves lip form and increases the soft tissue chin thickness. However, the contribution of variation in hard tissues to the soft tissue profile is not fully understood. (3,4) Ssoft-tissue changes associated with orthognathic surgery have been studied primarily in mandibular procedures. The influence of maxillary procedures on the relationship of hard-tissue to soft-tissue is less well documented. (5) Clearly, there is an increased interest in ABSTRACT Aims: The aim of this study is to assess Köle analysis (Tuinzing modification) for determining the possible positions of chin (soft and hard tissue) in skeletal Cl.I, Cl.II and Cl. III type of malocclusion of adult age group and for both genders. Materials and Methods:The study was carried out on the lateral cephalometric radiograph of (118) subjects of adult age group (18-25) years old; Cl I type (28 male and 19 female), Cl II type (19 male and 17 female) and Cl III type (18 male and female 17). SNA, SNB and ANB were used to estimate the type of skeletal malocclusion. For the analysis, 2 lines perpendicular to SN line are drawn touching the most anterior point of the upper lip-Ls (upper lip plane) and one from the infra orbital point-Or (orbital plane). The position of the chin points (hard and soft tissue) were assessed via determining the position of (Pog and Pg) respectively in relation to these two vertical planes using five scores: Score 1: give to the chin point that situated posterior to orbital plane. Score 2: give to the chin point that situated in a touch with orbital plane. Score 3: give to the chin point that situated in between orbital plane and upper lip plane. Score 4: give to the chin point that situated in a touch with upper lip plane. Score 5: give to the chin point that situated anterior to the upper lip plane. Results: The positions of Pog and Pg: Cl I mainly at score (2 and 3) respectively, Cl II mainly at score (1and 2) respectively and Cl III type Pog gave rise to slight increase of score (3 than 2) while Pg gave rise to slight increase of score (3 than 5) with no significant difference between genders for all classes. Conclusions: Köle analysis (Tuinzing modification) may be valuable for determining chin (soft and hard tissues) of Cl I, Cl II and Cl III types of malocclusion of adult age group and for both genders.