Introduction

The ultimate goal of periodontal therapy is to reestablish and maintain periodontal health and function, which can be achieved by surgical and nonsurgical treatments [1-4]. The non‐surgical periodontal therapy includes patient motivation, scaling and root planing (SRP), and oral hygiene instructions (OHI) [5]. Its goal is to eliminate or reduce the putative periodontal pathogens and shift the microbial flora to a more favorable environment [6]. It has been found that nonsurgical periodontal therapy can effectively treat chronic periodontitis [7-9]. However, several factors are reported to affect its success including patient‐related factors (e.g. smoking and disease severity); defect-related factors (e.g. infrabony defects and severe interproximal bone loss); and site‐specific factors (e.g. endodontic treatment and tooth type) [10-12]. At the Department of Periodontics and Community Dentistry (PCS) of the College of Dentistry, King Saud University, the nonsurgical periodontal therapy of chronic periodontitis is performed by periodontists, graduates attending the postgraduate programs in periodontology, and dental students in the undergraduate clinical courses of the bachelor curriculum (4^th and 5^th academic years), who are thoroughly supervised by experienced periodontists. Few studies have been published regarding the outcomes of nonsurgical periodontal therapy performed by undergraduate students. Vouros et al. [13] demonstrated successful treatment outcomes in patients with moderately and severely advanced periodontitis who were treated by senior undergraduate students at the Aristotle University of Thessaloniki in Greece. Another study conducted in Germany concluded that nonsurgical root debridement performed by systematically trained students was successful in treating chronic periodontitis [14]. Successful nonsurgical therapy in the undergraduate courses of the University of Basle in Switzerland was also reported by Walter et al. [15]. Up to our knowledge, no similar studies were carried out among undergraduate dental students at Saudi Universities. Therefore, the present longitudinal study aimed to assess the outcomes of nonsurgical treatment of chronic periodontitis by undergraduate students at the College of Dentistry, King Saud University.

Materials and Methods

This study was approved by the Research Ethics Committee of King Saud University (IRB Research Project No. E-18-3153). Participants were recruited from female patients who received nonsurgical periodontal therapy by the 4th and 5th-year undergraduate students, at the Girls University Campus of the College of Dentistry, King Saud University during 2018 and 2019. Informed consent was obtained from the included patients after explaining the study's nature. Inclusion criteria were >18-year-old patients with moderate or severe chronic periodontitis [16], complete clinical, periodontal, and radiographic documentation, complete nonsurgical SRP, at least one periodontal reevaluation visit 6 weeks after completion of the nonsurgical therapy, and one periodontal maintenance visit at least 3 months after completion of nonsurgical treatment [17]. At the initial visit, oral examination including periodontal charting and radiographic interpretation was carried out. The recorded periodontal parameters were plaque index (PI) [18], bleeding on probing (BOP; scored as present or absent) [19], and probing pocket depth (PPD). The number of all teeth, as well as number of molars (except wisdoms), were recorded. Following periodontal examination, diagnosis [16], and prognosis [20, 21], the enrolled patients received OHI and several weekly sessions of nonsurgical SRP under local anesthesia if needed. Hand instruments (Hu‐Friedy; Hu‐Friedy® Inc) and/or sonic scalers were used for root debridement in one quadrant or one side of the dentition per session with intervals of 1-2 weeks between sessions. The instrumented teeth had to exhibit hard and smooth root surfaces as being detected with a fine manual probe and they were finally rinsed with chlorhexidine (0.2%). At each visit, the patient's oral hygiene level was reassessed and reinforced if needed. All the clinical assessments and treatments were verified by experienced periodontists. Patients were scheduled by their treating dental students for periodontal reevaluation and maintenance visits. At these visits, the periodontal parameters were reassessed, the patient's oral hygiene was reinforced and root debridement was carried out where necessary. The collected data were analyzed statistically using the SPSS v.20. Means and standard deviations were calculated. The differences in the parameters between the initial visit and reevaluation and maintenance visits were evaluated with paired t-test at a significance level of <0.05.

Results and Discussion

Out of 40 patients screened, only 33 fulfilled the inclusion criteria and constituted the study sample. The patients' mean age was 31.2 ± 6.1 years. All patients were recalled at least once and 27 of them had been reevaluated more than once. The medical history revealed that 26 patients had systemic diseases (diabetes mellitus, hypertension, hypotension, hypothyroidism, asthma). Upon periodontal examination, localized and generalized severe chronic periodontitis were diagnosed in 17 patients and 16 patients were diagnosed with moderate chronic periodontitis. Table 1 represents the subjects’ characteristics before treatment.

Table 1. Characteristics of the study subjects prior to treatment (n= 33)

Over the study period, the mean PI reduced significantly from initial examination (46. 2 ± 14.5) to reevaluation visit (26.1 ± 12.3) (p <0.001) and maintenance visit (23.8 ± 10.2) (p <0.01). Similarly, the initial mean of BOP (46.2 ± 14.5) was improved significantly at both reevaluation (34.8 ± 13.3) and maintenance visits (31.7 ± 12.1) (p

<0.001) (Figure 1). Regarding the changes in the probing pocket depth following nonsurgical therapy, the mean number of teeth and tooth sites per patient with PPD <5 mm increased significantly after scaling and root planning from initial visit to reevaluation and maintenance visits (p <0.01) (Figures 2 and 3). In addition, the mean number of teeth and tooth sites per patient with PPD ≥5 mm at the initial visit decreased significantly at reevaluation and maintenance visits (p <0.001) (Figures 2 and 3). Considering the number of teeth, no significant differences were found in the total number of teeth and molars between the initial examination and the reevaluation and maintenance visits (p= 0.3) (Figure 4).