Pre-heated Resin Composite Restoration
Condition: The Effect of Preheating Cycles of Resin Composite on Both Hypersensitivity and Clinical Performance
MeSH terms: Hypersensitivity
Study type: Interventional

Summary: 
      this study is conducted to evaluate the post-operative hypersensitivity and clinical
      performance of preheated resin composite with different number of pre-heating cycles in class
      II carious lesions compared to resin composite restorations without preheating using Modified
      US Public Health Service Clinical Criteria (USPHS).
    

Detailed description: 
      1. Scientific Background One of the main problems associated with composite resin
           restorations is poor adaptation and gap formation between the restorative material and
           the cavity walls, resulting in the micro-leakage of oral fluids and accumulation of
           fluids responsible for many problems such as postoperative hypersensitivity, marginal
           discoloration and recurrent caries.

           Despite of recent developments in dental restorative materials and techniques,
           postoperative sensitivity following the application of a posterior resin composite
           restoration is often reported by dentists, as a clinical problem.

           Pre-application warming of dental resin composite restorative materials, is considered
           one of the modern modifications for the application of resin composite, which reduces
           viscosity and increases flowability, that in turn secures superior adaptation to the
           prepared cavity walls.

           Resin composite warming appliances found in the market nowadays, offer multiple choices
           for preheating either in different temperatures or in the form of the cassettes which
           could be compatible with different supplied forms from different manufacturers "capsules
           or syringes". Multiple cycles of preheating for the used composite resin syringe can
           affect both marginal integrity and mechanical properties of the resin composite
           according to the number of cycles applied.

           Increasing the temperature of dental resin composite before application can aid in
           monomer mobility inside its matrix giving high quality of degree of conversion and more
           highly cross-linked polymeric network. This kind of change of the rheology of the resin
           composite can aid in decreasing the postoperative hyper-sensitivity.

           However, an intensive review of literature failed to disclose the effect of using resin
           composite preheated for multiple times with different temperatures on the post-operative
           hypersensitivity.

        2. Statement of the problem Using the same resin composite syringe that previously
           preheated multiple times in different daily restorative cases, can adversely affect the
           properties and the performance of the applied resin composite.

        3. Hypothesis The null hypothesis is that using resin composite previously preheated for
           different cycles will not be different in reducing postoperative hypersensitivity,
           marginal integrity and mechanical properties of the resin composite as without
           preheating.

      D. The sample size calculation

        1. primary outcome: This power analysis used marginal integrity after 12 months as the
           primary outcome. Based upon the results of Kurdi R and Abboud SA (2016); Bulk Fill
           composite showed 13 cases with (Alpha) score and 4 cases with (Beta) score,
           respectively. The effect size (w) was 0.53. Using alpha (α) level of (5%) and Beta (β)
           level of (20%) i.e. power = 80%; the minimum estimated sample size was 28 cases. Sample
           size was increased to 35 cases to compensate for a drop-out rate of 25% after 12 months.
           Sample size calculation was performed using G*Power Version 3.1.9.2.

        2. secondary outcome: This power analysis used hypersensitivity grades after one day in
           patient with medium cavity depth as the primary outcome. The effect sizes w1 = (1.4) and
           w2 = (1.11) were calculated based upon the results of Ragab H (2018). Using alpha (α)
           level of (5%) and Beta (β) level of (20%) i.e. power = 80%; the minimum estimated sample
           size was a total of 11 subjects. Sample size was increased to a total of 14 subjects (7
           subjects per group) to compensate for a dropout rate of 25%. Sample size calculation was
           performed using G*Power Version 3.1.9.2
    

Intervention name(s): Pre-heating of resin composite before application; no pre-heating of resin composite before application
Intervention type(s): Procedure; Procedure
Intervention description(s): the effect of preheating of resin composite before application in class II cavities; The control group
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Health Services Research