TITLE: Rotary instruments in the treatment of chronic periodontitis: A randomized clinical trial

  ABSTRACT.BACKGROUND:
The study aimed at comparing the effectiveness of rotary instruments with hand instruments in non-surgical treatment of chronic periodontitis.

ABSTRACT.MATERIALS AND METHODS:
Thirty-eight patients with chronic periodontitis, enrolled to this randomized, controlled clinical trial, were divided into two groups. Patients in the control group received scaling and root planing with hand instruments, whereas patients in the test group received treatment with rotary instruments. Clinical assessment by plaque index, bleeding on probing, probing depth, gingival recession, and clinical attachment level was made prior to and at 6 months after treatment. Differences in the clinical parameters were analyzed using the Wilcoxon signed rank test and Mann–Whitney U test.

ABSTRACT.RESULTS:
Both treatments resulted in a significant improvement in all clinical recordings, but no differences in any of the investigated parameters were observed at baseline between the two groups.

ABSTRACT.CONCLUSION:
Non-surgical periodontal therapy with the tested rotary instruments may lead to clinical improvements comparable to those obtained with conventional hand instruments.

BODY.INTRODUCTION:
The ultimate objective of all root treatment procedures is to effectively remove plaque and calculus without causing root surface damage and to render the treated root surface biologically compatible with host periodontal tissue. However, complete removal of subgingival calculus with hand or power-driven instruments is difficult to achieve, even when surgical approach is used.  Various power-driven and hand instruments are currently available for scaling and root planing. Although hand scalers are frequently used, considerable time and manual dexterity are required for their effective operation.[1] Moreover, hand scalers are unable to reach the deeper root surfaces where the periodontal pockets are more than 4 mm deep.[23] Consequently, ultrasonic scalers have become more widely used in recent years. Although they are simple to use, it is often difficult to achieve smooth and calculus-free root surfaces.[456] Dental plaque adheres more readily to roughened root surface created by the use of ultrasonic scalers.[7] To overcome these challenges associated with the use of ultrasonic scalers and hand instruments, carbide rotary instruments for scaling and root planing have been developed.  Some studies suggested that hand instruments produce smoother root surface,[891011] while other studies were in favor of use of ultrasonic instruments to achieve a smooth surfaces, as these were found to be less damaging to the root surfaces than hand curettes.[1213] Clinical studies have shown that attachment gain and pocket probing depth reduction are identical after the use of hand instruments and sonic or ultrasonic scaling.[141516]  Most of the data available in literature compare the efficacy of hand curettes and ultrasonic instruments. However, until now, hardly any study is available concerning the clinical outcome following non-surgical periodontal treatment with rotary carbide instruments. Therefore, the aim of the present study is to assess the clinical effectiveness of carbide bur when compared to scaling and root planing with hand instruments.

BODY.MATERIALS AND METHODS:
All the subjects in the present study were recruited from the Department of Periodontology and Implantology. The ethical committee of Himachal Institute of Dental Sciences approved the study protocol, and all participating patients signed an informed consent at the beginning of the study.

BODY.MATERIALS AND METHODS.SELECTION OF SUBJECTS:
Thirty-eight patients (20 females and 18 males) with advanced chronic periodontitis (Armitage 1999)[17] were recruited for the study. The inclusive criteria for patient selection were as follows:  
Adults between 18 and 70 years of ageGood level of oral hygiene [as a criterion for good level of oral hygiene, a mean plaque index (PlI) score <1 was chosen] (Lӧe 1967).[18] The exclusion criteria were:  
Patients seeking treatment of periodontitis for the last 2 yearsPatients using antibiotics for 12 months prior to treatmentPatients with any systemic diseasePatients using medicated mouth washesPregnancy.
  All subjects were enrolled in a hygiene program 6 weeks prior to the treatment. They received professional supragingival tooth cleaning with ultrasonic scalers (supragingival ultrasonic tip) and oral hygiene instructions. A supragingival scaling and reinforcement of oral hygiene was performed at baseline as well as 4, 8, 12, 16, 20, and 24 weeks after treatment.

BODY.MATERIALS AND METHODS.STUDY DESIGN AND TREATMENT:
The present study was conducted between June 2012 and January 2013, and was performed according to a parallel group design. All patients were treated according to a "one-stage procedure" with either (1) the rotary instruments, Desmoclean (Hager, Germany) [Figure 1] or (2) Gracey curettes (Hu-Friedy Co., Chicago, IL, USA) [Figure 2].  Figure 1The rotary instrument along with micro-motor contra-angle handpiece  Figure 2Gracey curettes  In the test group or rotary instrument group, there were 19 patients (12 females and 7 males). In the test group, carbide burs with non-cutting, elliptical, and hexagonal head were used with micro-motor contra-angle handpiece at 8000 rpm (rotation per minute) with light pressure and water spraying [Figure 1]. In the control group or Gracey curette group, there were 19 patients (8 females and 11 males). Instrumentation for both groups was performed until the root surface was adequately debrided and planed. All the instrumentation was done under local anesthesia by one experienced operator. The curettes were sharpened at the operator's request and no restrictions in instrumentation time were set in any group.

BODY.MATERIALS AND METHODS.CLINICAL MEASUREMENTS:
The following parameters were recorded at baseline (after 6 weeks pre-treatment phase) and 6 months after therapy:  
Full mouth plaque score (FMPS) (O'Leary et al. 1972)[19]Probing depth (PD)Gingival recession (GR)Clinical attachment level (CAL)Bleeding on probing (BOP).
  Presence or absence of bleeding on probing was assessed up to 30 s after probing. The measurements were made at six aspects per tooth – mesio-buccal (mb), mid-buccal (b), disto-buccal (db), mesio-lingual (ml), mid-lingual (l), and disto-lingual (dl) – using a manual periodontal probe.

BODY.MATERIALS AND METHODS.RANDOMIZATION OF THE STUDY:
Sixty-eight patients underwent a screening examination which included full mouth probing, plaque index, and a radiographic examination. Thirty-eight patients with generalized advanced chronic periodontitis, who fulfilled all the prerequisites, were finally recruited for the present study. This screening test and final recruitment was conducted by examiner (A). These 38 patients were randomly assigned to two treatment groups using random tables. The randomization list was kept by the second examiner (B), and the patients were given sealed envelopes indicating the treatment modality. Now, examiner (C) opened those envelopes and performed the therapy. Examiner (A), who was unaware of the treatment received, performed the recording of all clinical parameters. And finally, examiner (B) compiled the data received from examiner (A) according to the randomization list. At all time points, the outcome of research was assessed blindly.

BODY.MATERIALS AND METHODS.STATISTICAL ANALYSIS:
The Wilcoxon signed ranks test was used to compare the baseline data to those at 6 months for each treatment group. Comparisons between treatment groups at baseline and those at 6 months were accomplished with the Mann–Whitney U test. The α-error was set at 0.05. The power of study, given 1 mm as the significant difference between the groups, was calculated to be 0.99.

BODY.RESULTS.FMPS AND BOP:
The FMPS and BOP for both the treatment groups at baseline and 6 months are summarized in Table 1. No statistically significant differences were found between these groups.   Table 1 FMPS and BOP: Mean values (in percentage) at baseline and 6 months 

BODY.RESULTS.CLINICAL PARAMETERS IN SINGLE-ROOTED TEETH:
In the rotary instrument group, 312 single-rooted teeth and in the Gracey curette group, 395 single-rooted teeth were treated. At moderately deep pocket (4-5 mm) sites, in the rotary instrument group, pocket depth at baseline (4.5 ± 0.5) reduced to 3.7 ± 1.2, whereas in the Gracey curette group, the pocket depth reduced from 4.5 ± 0.3 to 3.4 ± 1.1 [Table 2]. At deep pocket site (initial PD > 6 mm), in the rotary instrument group, PD reduced from 7.2 ± 1.5 to 6.5 ± 1.8 and in the Gracey curette group, it reduced from 6.7 ± 0.9 to 5.4 ± 1.8. But while comparing these two groups, the results were statistically nonsignificant. Similarly, other clinical parameters like GR and CAL gave statistically nonsignificant results [Table 3].   Table 2 Single-rooted teeth: Mean PD, GR, and CAL (±SD) at baseline and 6 months at sites with initial pocket depths of 4-5 mm ( n =38)   Table 3 Single-rooted teeth: Mean PD, GR, and CAL (±SD) at baseline and 6 months at sites with initial pocket depths >6 mm ( n =38) 

BODY.RESULTS.PARAMETERS IN MULTI-ROOTED TEETH:
In the rotary instrument group, 256 multi-rooted teeth and in the Gracey curette group, 302 multi-rooted teeth were treated. Clinical improvement was noticed in both moderately deep pocket sites and deep pocket areas. But comparison of groups showed them to be statistically nonsignificant [Tables 4 and 5].   Table 4 Multi-rooted teeth: Mean PD, GR, and CAL (±SD) at baseline and 6 months at sites with initial pocket depths of 4-5 mm ( n =38)   Table 5 Multi-rooted teeth: Mean PD, GR, and CAL (±SD) at baseline and 6 months at sites with initial pocket depths >6 mm ( n =38) 

BODY.DISCUSSION:
In order to provide a root surface compatible for soft tissue healing, the old concept of extensive cementum removal has been questioned by various experimental studies.[2021] Nowadays, the trend in therapeutic methodology in periodontology is minimum aggressive approach in both surgical and non-surgical treatments.  In the literature, there are large numbers of studies comparing the effect of hand curettes and ultrasonic scalers on root surface roughness.[456111314] Some studies found that ultrasonic instruments produce rough and irregular root surface as compared to hand curettes,[45] whereas other studies suggested that clean and smooth root surface can be achieved with the use of ultrasonic scalers.[1314] Kishida and Sato stated that ultrasonic instrument produces smooth and regular surface as compared to hand curette.[12] But the use of a diamond bur at high speed increased the risk of root surface damage;[22] similar results were obtained by Evian and Horowitz.[23]  Solis Moreno et al. compared the root surface roughness after using Gracey curettes, termination diamond burs (40 μm), a piezoceramic ultrasonic scaler, and a piezosurgery ultrasonic scaler, using confocal microscopy and scanning electron microscopy.[24] They found that the termination diamond burs (40 μm) produced a rougher surface than the ultrasonic instruments and the hand curettes. Whereas Dahiya et al. found a smoother root surface with rotary bur as compared to hand curettes and ultrasonic scalers.[25] The difference in the results of these two studies can be explained on the basis of different characteristics of bur. In the previous study, diamond burs were used, whereas in latter study, non-cutting carbide burs were used.  Khatiblou and Ghodossi studied the effect of root roughness on periodontal healing and found that periodontal healing following flap surgery occurred regardless of whether the subgingival root surface was rough or smooth.[26]  The present randomized clinical trial evaluated the clinical effectiveness of rotary instrument and hand curettes. In the rotary instrument group, four different carbide burs (I = 23 mm, II = 29 mm, III = 26 mm, and IV = 29 mm) with non-cutting, elliptical, and hexagonal head in four different shaft designs were used according to manufacturer's instructions [Figure 1]. Carbide burs were used at 8000 rpm with light pressure and water spraying, so as to avoid excessive damage due to frictional and thermal insults. Similar parameters were adopted by Dahiya et al. in their study.[25]  No restriction in the instrumentation time was set in any group. Instrumentation in both groups was performed until a smooth and hard surface was achieved. Limiting the time might result in under- or over-instrumentation of root surfaces. The smoothness of the root surface was assessed using a periodontal probe (Hu-Friedy PCP 11; Hu-Friedy Co.) and explorer (Hu-Friedy Wilkins-Tufts 17/23; Hu-Friedy Co.). This method of evaluating the root surface smoothness was similar to the method used by Ioannou et al.[16]  All clinical parameters were assessed at baseline and after 6 months of therapy because healing following non-surgical therapy is almost complete at 3 months. However, a slower ongoing, but limited healing can continue for a longer time (up to 9 or more months) following the treatment.[27] Ioannou et al.[16] and Sculean et al.[28] also evaluated the clinical parameters at baseline and 6 months after therapy.  The results of our study suggested that both hand curettes and rotary instruments are effective treatment modalities for periodontal disease. When interpreting the results, it has been noted that sites where probing depths were initially deep showed more GR, more gain of CAL, and deeper residual PD at 6 months examination than the sites with initial moderate PD. Some clinical studies have demonstrated that the reduction of PD and the improvement of CAL after both surgical and non-surgical periodontal treatments are dependent on the initial PD.[2930]  But while comparing carbide bur with hand curettes, in terms of periodontal healing by using PD, CAL, and GR clinical parameters, statistically nonsignificant results were found. The possible explanation for such results could be the enrollment of all the patients in supragingival professional tooth cleaning and oral hygiene reinforcement program at baseline as well as 4, 8, 12, 16, 20, and 24 weeks after treatment. Some clinical studies have shown that root surface debridement with either hand curettes or ultrasonic devices leads to similar clinical and microbial improvement of periodontal conditions.[3132] Oberholzer et al. did not find any significant differences in pocket depth reduction and clinical attachment gain after creating rough or smooth surface during flap operation. This indicates that subgingival roughness does not interfere with healing if there is good supragingival plaque control and that long-term success of this treatment is dependent on the quality of maintenance therapy. But a smooth surface may be advantageous near the gingival margin, since a smooth surface is less likely to accumulate plaque than a rough surface.[33]  Because of lack of published data regarding the effect of carbide bur on clinical parameters like PD, CAL, and GR, we could not compare the results of the present study with those of other studies.

BODY.CONCLUSION:
The present study shows that non-surgical periodontal therapy with both hand curettes and rotary burs was well tolerated as all the treated pockets showed uneventful healing. Moreover, the use of rotary instruments in the treatment of chronic periodontal disease gave comparable results with traditional approach of scaling and root planing carried out with hand curettes. Our study also emphasizes the importance of scaling and root planing for maintenance of good periodontal health. Consequently, it is also suggested that more studies evaluating healing outcome and patients' compliance after both treatment modalities are needed in order to draw definitive conclusion about the stability of each therapeutic approach.

Question: Compared to received scaling and root planing with hand instruments what was the result of received treatment with rotary instruments on Clinical improvement in multi-rooted teeth ?
Evidence: At deep pocket site (initial PD > 6 mm), in the rotary instrument group, PD reduced from 7.2 ± 1.5 to 6.5 ± 1.8 and in the Gracey curette group, it reduced from 6.7 ± 0.9 to 5.4 ± 1.8. But while comparing these two groups, the results were statistically nonsignificant. Similarly, other clinical parameters like GR and CAL gave statistically nonsignificant results [Table 3].
Answer: no significant difference