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E4 ◊Page E3 ORTHO TRIBUNE Dental Tribune Middle East & Africa Edition | 3/2018 Table 1. Descriptive Statistics of Pre-Treatment and Post Treatment Arch Width and Arch Depth Values Are Shown (mm) Variable Mean Std. Deviation Std. Error Mean Mean Difference T-Test Value P Value Maxillary Inter-canine width Pre treatment Post treatment Mandibular Intercanine width Pre treatment Post treatment Maxillary Inter 1st PM width Pre treatment Post treatment Mandibular Inter 1st PM width Pre treatment Post treatment Maxillary Inter 2nd PM width Pre treatment Post treatment Mandibular Inter 2nd PM width Pre treatment Post treatment Maxillary Inter molar width Pre treatment Post treatment Mandibular Inter molar width Pre treatment Post treatment Maxillary arch depth Pre treatment Post treatment Mandibular arch depth Pre treatment Post treatment 32.97 34.24 24.10 26.67 39.29 41.17 31.87 34.35 43.88 46.03 37.11 39.88 48.29 49.68 42.86 43.15 33.23 31.97 30.43 31.03 1.27 1.08 2.25 1.30 1.73 1.76 1.12 1.26 2.03 1.53 2.48 1.57 2.90 2.02 1.60 1.54 2.67 1.47 3.06 1.82 aP-value ≥ 0.05 Non-significant difference. bP-value < 0.001 - Very Highly Significant difference. cP-value < 0.01 - Highly Significant difference. dP-value < 0.05 Significant difference. 0.29 0.25 0.52 0.30 0.40 0.40 0.26 0.29 0.47 0.35 0.57 0.36 0.67 0.46 0.37 0.35 0.61 0.34 0.70 0.42 -1.27 -2.57 -1.88 -4.194 0.001b -4.404 < 0.001b -3.980 0.001b -2.48 -6.705 < 0.001b -2.15 -2.77 -1.39 -3.645 0.002c -3.687 0.002c -2.599 0.018d -0.29 -0.804 0.432 1.25 4.029 0.001b -0.59 -1.268 0.221 Table 1. Descriptive Statistics of Pre-Treatment and Post Treatment Arch Width and Arch Depth Values Are Shown (mm)a Variables U1 to N-A Angular Pre treatment Post treatment U1 to Palatal plane angle Pre treatment Post treatment U1 to SN plane angle Pre treatment Post treatment L1 to N-B (Angular) Pre treatment Post treatment L1 to Mandibular plane angle Pre treatment Post treatment L1 to Occlusal plane angle Pre treatment Post treatment Mean Std. Deviation Std. Error Mean Mean Difference T-Test Value P Value 24.56 27.35 112.16 115.89 113.74 116.74 24.27 28.85 96.13 100.42 8.05 12.72 6.62 5.58 6.99 5.12 6.82 5.03 2.71 1.63 3.43 1.69 3.41 1.42 1.52 1.28 1.60 1.17 1.56 1.15 0.64 0.38 0.81 0.40 0.80 0.34 -2.79 -3.74 -5.524 < 0.001*** -6.853 < 0.001*** -3.00 -5.266 < 0.001*** -4.58 -4.28 -4.67 -9.320 < 0.001*** -6.898 < 0.001*** -6.477 < 0.001*** aP-value ≥ 0.05 Non-significant difference, P-value < 0.05 Significant* difference, P-value < 0.01 - Highly Significant** difference, P-value < 0.001 - Very Highly Signifi- cant*** difference. Table 2. Descriptive Statistics of Pre-Treatment and Post Treatment Upper Incisor and Lower Incisor Inclination Values Are Shown (Degrees)a buccal cusp tips of right and left sec- ond premolars. Inter first molar width: Measure- ments were made between the me- sio-buccal cusp tips of right and left first molars. 3.1. Arch Depth First line is drawn connecting the central fossa of first molars on the right and left sides. A second line was drawn perpendicular to the first, bisecting the contact point between the central incisors. Cephalometric tracings were per- formed using digital cephalometrics (Nemo Ceph, version 6.0, Spain). Pre- treatment and post-treatment read- ings of each patient were evaluated from the software and pre treatment and post treatment superimposition was also carried out. 3.2. Upper Incisor Inclination U1 to SN plane angle: It is the infe- rior inside angle formed between the long axis of the upper incisor and Sella-nasion plane. U1 to Palatal plane angle: It is the inferior inside angle formed between the long axis of the upper incisors and palatal plane (formed by line joining the an- terior nasal spine and posterior nasal spine) U1 to N-A (Angular):- It is the angle formed by the intersection of the long axis of the upper central in- cisors and the line joining the nasion to point A. L1 to Mandibular plane angle: It is the angle formed by the intersection of the long axis of the lower incisor with the mandibular plane. It indi- cates the inclination of the lower incisors. L1 to Occlusal plane angle: It is the inferior inside angle formed by the intersection of the long axis of the lower incisor with the occlusal plane. This angle is read as a positive or neg- ative deviation from the right angle. L1 to N-B (Angular): It is the angle formed by the intersection of the long axis of the lower central inci- sorsandthe line joining the nasion to point B. Results All the pretreatment and post treat- ment measurement of scanned digi- tal models and the measurement obtained from the scanned cepha- lograms were subjected to statistical analysis using software SPSS (statis- tical package for social sciences) ver- sion 21.0 and Epi-info version 3.0 and Paired t-test was applied to see the statistical significance - It was used for comparison of 2 mean values ob- tained from a same group or a pair of values obtained from the same sample. The P-value was taken significant when less than 0.05 (P < 0.05) and Confidence interval of 95% was tak- en. The following results were obtained after the statistical analysis: Discussion Self ligation appliances regained popularity since the early nine- ties because of the certain advan- tages which were claimed such as: increased patient comfort, better oral hygiene, increased patient co- operation, less chair time, shorter treatment time, greater patient ac- ceptance, expansion, and less dental extractions (10, 12, 13). Self ligation appliances significant amount of expansion with no apical root resorption and with increase in buccal bone thickness. Self ligation appliance also offer precise control of tooth during translation, reduce overall anchorage demands, rapid alignment and more certain space closure. achieved Alleviating dental crowding without extractions requires an increase in arch perimeter or interproximal re- ductions to attain good teeth align- ment (14). In the absence of distaliza- tion, the changes in arch dimensions involve transverse expansion and increased proclination of teeth. Passive self-ligation treatment phi- losophy (10) is based on providing optimum force levels for orthodon- tic tooth movement which should be just high enough to stimulate cel- lular activity without completely oc- cluding the blood vessels in the PDL. Light continuous forces will produce continuous, frontal resorption and will not overpower the periodontal and orofacial muscltature, and will prevent proclination of anteriors and causes more expansion in the transverse direction. Photoelastic modelshowed lower stress in peri- odontal tissue with self-ligating ap- pliance as compared to conventional bracket system (15). Intra arch dimensional changes in both maxillary and mandibular arches in moderate crowding cases treated non-extraction with a pas- sive self ligation appliance (Damon 3MX) were analyzed using digitized models and digital cephalograms. This study showed an increase in maxillary intercanine width, inter 1st premolar width, inter 2nd premolar width and inter molar arch width (Table 1). More transverse expansion was observed in the region of 1st and 2nd premolars as compared to the inter-canine and inter molar region. More expansion in the premolars region can be because of lip bumper effect which minimizes the proclina- tion of anterior teeth and allow more expansion in posterior region. Previ- ous study also showed majority of transverse changes in the premolar areas in both upper and lower arch- es, with less expansion in the canine and molar region (16, 17). While assessing maxillary arch depth, the study showed (Table 1) a decrease in arch depth which can be because of more of transverse expansion, which created space and helped in unraveling of crowding in upper anteriors and less proclina- tion. Overlapping because of crowd- ing in anteriors was reduced with minimal proclination. Because of lateral expansion and derotation in posterior segment, some amount of mesial movement of molars could also have occurred, to improve molar relation. The inclination of upper incisors was evaluated using U1 to N-A (Angular), U1 to palatal plane angle and U1 to SN plane angle (Table 2). Results showed an increase in proclination which was statistically significant. Similar studies done in past also showed sig- nificant amount of arch expansion in the maxillary arch (8). In the mandibular arch also an in- crease in mandibular intercanine width, inter 1st premolar width, inter 2nd premolar width and inter mo- lar arch width was observed (Table 1) similar to maxillary arch. Study also showed an increase in the man- dibular arch depth (Table 1). Change in inclination of lower incisors was evaluated using L1 to N-B (Angular) values, L1 to mandibular plane angle and L1 to occlusal plane angle (Table 2). Results showed increase in pro- clination which was statistically sig- nificant. Insufficient interproximal reduction can be one of the cause of increased proclination of lower an- teriors and increase in arch depth in mandibular arch. Results of the study also showed more increase in the mandibu- lar intercanineandinterpremolar widths as compared to the inter molar width with increase in arch depth and increase in proclination. Previous studies showed transverse expansion and incisor proclination, and more expansion in the inter mo- lar region (11, 18). 5.1. Conclusion Study showed increase in inter- canine width, inter 1st premolar width, inter 2nd premolar width and inter molar width in both maxillary and mandibular arches, with more expansion in premolar area. Arch depth was found to be decreased in upper arch it was found to be in- creased in lower arch however the passive self-ligation appliance can be used as a valuable tool because it minimizes the proclination which could have been produced during unraveling of crowding in both the arches without the space which have been gained with passive self ligation appliance by posterior expansion. 5.2. Limitations of Study Present study had the limitations of small sample size of twenty patients and retrospective in nature. As retro- spective studies are always subject to various types of bias because of the lack of randomization. Hence, the results obtained from the current study should be further strength- ened using a larger sample size and preferably using a prospective study model. in preschool children. References 1. Brunelle JA, Bhat M, Lipton JA. Prevalence and distribution of se- lected occlusal characteristics in the US population, 1988-1991. 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