INTRODUCTION:Increased tooth mobility as a consequence of untreated periodontitis leads to tooth loss due to increased periodontopathogens. The use of metronidazole in combination with spiramycin is one of the effective conventional treatments of severe periodontitis (grade C), but it has several side effects. On the other hand, diode laser (980 nm) is also recommended to treat severe periodontitis (grade C) due to its bactericidal and detoxifying effects. OBJECTIVE: Measure and compare the grade of teeth mobility after intra-pocket application of diode laser therapy versus systemic antibiotic in severe periodontitis (stage 3 grade C). MATERIALS AND METHODS:A Randomized controlled clinical trial was conducted on 50 patients with stage 3 grade C periodontitis divided equally into two groups. Group I (test group) treated by scaling and root planing (SRP) together with intrapocket application of diode laser. Group II (control group) treated by SRP and systemic antibiotic administration. Patients were evaluated in terms of mobility degree at baseline, 4 th and 12 th week postoperatively. RESULTS:The degree of teeth mobility decreased significantly from baseline to the end of the treatment in each group individually. However, there was no significant difference between both groups at the end of the treatment. CONCLUSION: Laser therapy and systemic antibiotic are effective treatment modalities in decreasing the degree of mobility of teeth with stage 3 grade C periodontitis. However, to avoid the systemic antibiotic side effects and bacterial resistance of long term use, intra-pocket laser therapy can be recommended.

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Statement of the problem:The increased amount of crystals in zirconia ceramics and the absence of glass make them resistant to acid etching and chemical bonding through traditional silane application. Alternative durable bonding techniques between zirconia and resin cement are still mandatory. Objective: This study was conducted to investigate the effect of two adhesive promoter types and two resin cements on the shear bond strength of sandblasted ultra-translucent zirconia plates to resin cement. Materials and Methods: BruxZir anterior Zirconia blank was sliced to obtain forty-two ultra-translucent zirconia plates, followed by their sintering. All the plates were sandblasted using 50 µm alumina particles. Plates were divided into three groups according to the type of adhesive promoter: Group A: no primer, Group B: coated with zirconia primer, and group C: coated with a universal bonding agent. One plate from each group was examined under Scanning Electron Microscope. Half of the plates in each group were bonded to conventional composite resin cement while the other half were bonded to Phosphate containing one following the manufacturers' instructions. All plates were stored in an incubator containing distilled water at 37 ºc for 1 week. Shear bond strength test was performed using universal testing machine. Data obtained were analyzed statistically. Results: The application of Z prime and bonding to conventional resin cement resulted in the highest shear bond strength values (19.58 MPa) followed by no primer application and bonding to phosphate resin cement (15.8 MPa). Universal bonding agent showed the lowest bond strength values with both resin cements. Conclusions: Application of MDP-containing primer showed the highest bond strength with conventional resin cement while the universal adhesive showed weak bond strength with both resin cements. Resin cements reacted almost equally when used directly on zirconia without primer application.