Effect of Crown Material on Gingival Microbial Colonization

* Prior approval from SOD ethical committee has been received. * All patients presenting to the General OPD of School of Dentistry, Islamabad will be screened. Those patients who fulfill the criteria will be referred to the Prosthodontics department. * The patients will undergo detailed history and oral examination after informed consent (Annexure-A). Patients will undergo radiographic investigation and based on this information they will be selected for the study according to the exclusion and inclusion criteria. * Eligible participants will be randomly assigned to one of the following groups using a computer-generated sequence with allocation concealment via sealed opaque envelopes:

* Group A: Control group * Group B: Full-coverage PFM crowns * Group C: Full-coverage Zirconia crowns * Baseline gingival samples will be collected with the help of sterile swab from the target tooth region prior to prosthesis placement and at the follow-up visits i.e. 1, and 3 months; both for experimental groups and control group. * Microbial analysis will be conducted through culture techniques to quantify CFUs and identify species. * A summary of the micro-organisms, their incubation media, temperature and time is presented in the following table:

Table 1: Summary of the micro-organisms, their incubation media, temperature and time Micro-organism Growth Media Temperature Incubation time Candida albicans Saboraud Agar 370C 24-48 hours Streptococcus mutans BHI broth 370C 24-48 hours Staphylococcus aureus BHI broth 370C 24-48 hours Porphyromonas gingivalis BHI broth 370C 18-24 hours

* Alongside, the same sample from sterile swabs will be smeared by fixating it on a microscopic slide and then Candida albicans will be stained by Periodic Acid Schiff technique, and the bacterial species using Gram staining. * All participants will receive standardized verbal and written instructions oral hygiene instructions to control for hygiene-related variation