Aim: This study investigated the effect of preparation design and thermal cycling on the marginal accuracy of hybrid ceramic laminate veneers.Materials and Methods: A total of twenty 3D printed dies of central incisors prepared with 2 preparation designs; butt joint and palatal wrap design were fabricated.Each type of preparation was assigned into 2 subgroups (n=5/ each subgroup) according to the type of material used for fabrication of the laminate veneer; hybrid ceramic and lithium disilicate (served as control).Marginal discrepancy was evaluated using a digital microscope before and after thermocycling.Results: Statistically analysis of marginal gaps revealed that before thermocycling, butt joint design demonstrated larger average marginal gaps compared to palatal wrap design in both Enamic (76.18±0.07)and E-max (76.11±0.09µm).While smaller gaps was recorded in palatal wrap design E-max (63.27±0.28µm) and Enamic (63.21±0.05).After thermocycling, palatal wrap design showed larger average marginal gaps in E-max (166.75 ±16.67 µm) and Enamic (157.52±15.44);while a significantly lower gap was recorded in butt joint design for Enamic (137.41±0.2) and E-max (137.41±0.09µm).There was no statistical significant difference between marginal gaps in Emax and Enamic within the same preparation design.Conclusion: Before thermocycling, the palatal wrap design laminate veneers showed smaller marginal gaps compared to butt joint.Thermalcycling caused a detrimental increase in marginal gaps .The effect of thermocycling was more profound on palatal wrap design veneers.The marginal accuracy of hybrid ceramic laminate veneers were statistically comparable to that of lithium disilicate.
OrthodonticsAim: Clear aligner treatment's main drawback is that the patient decides how long to wear them each day.For clear aligner therapy to be successful, compliance is essential.A poor treatment outcome would arise from noncompliant patients.Methods: The study was a randomized clinical trial of 2 parallel groups (7 patients per group) who underwent clear aligner orthodontic treatment having an age range of 17-24 years.A part-time group wore the aligners for 16 hours per day and a fulltime group wore the aligners for 22 hours per day.The study investigated the first eight aligners of the treatment.Compliance was recorded for each patient.Pain was evaluated by visual analogue scale.Periodontal health was examined by detection of bleeding upon probing.Results: Bleeding upon probing was detected in 21 percent of the patients (2 in full-time group and 1 part-time group).The intensity of pain peaked at 24 hours (mean VAS score 4.57±1.13 in part-time group and 4.86±0.9 in full time group).Part-time group had a mean wear time of 14.97±0.37hours while full-time group had a mean wear time of 19.54±0.75hours.Conclusion: There were no significant differences between part time and full time groups regarding periodontal parameters considered and pain intensity.Instructions of wearing the aligner for a longer duration resulted in increased overall adherence to wearing the aligner.
OrthodonticsAim: The aim of this clinical trial is to investigate maxillary first molar rotation during maxillary canine retraction at 6 weeks re-activation intervals with elastic power chain in first premolar extraction cases.Material and methods: a total of 20 quadrants of 10 orthodontic patients requiring maxillary canine retraction after extraction of upper 1 st premolars were recruited.Mini-screws (TADs) were used directly for maximum anchorage.Canines were retracted on 0.016×0.022-inchstainless steel arch wire using elastic power chain extending from a power arm on canine bracket to the miniscrew.Cone beam computed tomography (CBCT) was used to measure the upper first molar rotation.Results: The mean difference of the first molar rotation between pre-retraction and post-retraction measurements was 0.6250 o ± 0.6 o which was statistically insignificant.Conclusion: There is no significant difference between pre-retraction and post-retraction upper first molar rotation re-activated every 6 weeks using power chain.
