A Comparative Evaluation of Root Surface Roughness After Instrumentation with Gracey Curettes, Ultrasonic and Piezo-Surgery Driven Diamond Coated Tips: An In-Vitro SEM Study

Introduction

Periodontitis is a disease characterised by an interplay of infection by bacterial pathogens followed by inflammation. Several factors including genetic, This work is licensed under a Creative Commons Attribution-NonCommercial 4.0. environmental, dietary elements play a major role in the etiopathogenesis of this disease. Of this, the local factors consisting plaque and calculus are the primary etiological factors as they act as a reservoir of micro-organisms that can initiate the disease process. Root surfaces exposed to biofilm and calculus pose a different problem. Calculus deposits often become lodged within irregularities in the cementum on root surfaces.¹ Subgingival calculus, being porous, houses bacteria and endotoxins, underscoring the importance of thorough and complete removal.² This is achieved by non-surgical treatment or scaling and root planing. Root planing is the process by which residual embedded calculus and portions of cementum are removed from the roots to produce a smooth, hard, clean surface.³ This is usually achieved by manual or power-driven instrumentation.

Manual root planing is achieved using curettes and is often time consuming. Apart from curettes, alternative instruments for mechanically preparing root surfaces include sonic, ultrasonic, and rotary devices. Irrespective of whether the instrumentation is done by manual or power-driven means, the ultimate goal of non-surgical therapy is to produce a clean and smooth surface without iatrogenic removal of excess cementum or formation of microscopic niches that can cause further accumulation of deposits. The aim of this study was to evaluate roughness produced on the root micro topography by instrumentation with Gracey curettes, Ultrasonic scaler tips and Piezo surgical diamond coated tips using scanning electron microscopy (SEM).

Materials and Method

Out patients visiting the Department of Orthodontics at the institute were selected for the study after obtaining clearance from the Institutional Ethical Committee. A total of 66 mandibular premolar teeth indicated for extraction as a part of orthodontic treatment were collected, stored and mounted. Multi-rooted teeth, teeth with caries, developmental deformities, erosion and abrasion defects, were excluded.

Collected samples were washed in running water for 30 seconds and stored in 0.9% NaCl (normal saline) throughout the study period. They were divided randomly into three groups with 22 samples each: Group A, Group B and Group C.

Each tooth was mounted in a plastic tube filled with acrylic resin, which was 2 cm in height keeping either of the two proximal surfaces exposed without any visible surface irregularities. An area approximately of 5 mm located 2 mm apical to the cementoenamel junction (CEJ) was selected for instrumentation as shown in Figure 1 a.

The samples were numbered and randomly divided into three groups as mentioned below (Depicted in Figure 1b, c, d):

• Group A: Root planing using Gracey curettes no.5 and no.6 (Hu-Friedy, Chicago, IL, USA)
• Group B: Root planing using ultrasonic scaler (Woodpecker UDS-J) on medium power mode with Periodontal P3 tip.
• Group C: Root planing using W&H Piezomed piezo surgery unit on function On /Mode Periodontics (ROOT), with the insert (P2RD, P2LD).

The same operator performed the instrumentation on mounted root surfaces, executing 15 vertical strokes in the apico-coronal direction.

The root portion of the teeth was sectioned longitudinally using high speed diamond disc with copious water coolant. Each sample was mounted on a metal stub and dried in a silica gel vacuum desiccator for one hour. Samples were then sputter-coated with 25 nm of gold for 10 min and were examined under the SEM (x1500). Root surface roughness was scored based on Lie and Meyer Loss of Tooth Surface Index⁴ (Table 1). Figure 2 depicts the study design carried out.

Statistical Analysis

The collected data was analysed using both descriptive and inferential statistics. Chi-square test, t test, ANOVA was used. P <0.05 was considered significant. The analysis of the data was carried out using SPSS version 20 software.

Results

Comparison of root surface roughness among the three tested methods in terms of slight loss, definite loss and considerable loss is presented in Table 2. The mean surface roughness scores recorded amongst the three tested methods is mentioned in Table 3. Comparison of mean surface roughness scores in different methods showed a statistically significant difference among groups (P <0.004). Graph 2 represents the mean root surface roughness recorded for the three tested methods.

Multiple comparisons of mean surface roughness scores showed that there was no difference between Gracey curette and Ultrasonic scaler tip (P=0.063). No statistical significant difference was found between Gracey curette and Piezo surgical unit (P=0.984). However, a statistically significant difference was found between Ultrasonic scaler tip and Piezo surgical unit with P <0.004. It can be inferred from the results that the surface roughness is different in both Ultrasonic scaler tip and Piezo surgical unit groups.

Discussion

The hard tissue wall of the periodontal pocket is comparatively rough as opposed to other areas that are not exposed. Disease succession occurs due to accumulation of microbes in these rough surfaces. The microscopic lacunae formed on the cementum surface becomes a niche for accumulation of plaque, this in turn serves as a foci of infection.^5,6 Hence, removal of these defects and achieving a clean, smooth surface is a primary essential step in periodontal therapy.

Certain amounts of contaminated cementum is also removed by root planing. Periodontal pathogens produce endotoxins that harbour the cementum leading to its contamination. Studies reveal that the migration of favourable cells during periodontal healing is impaired by these toxins. Adequate healing is ensured only by the presence of a biologically acceptable root surface.⁷

Daly et al., showed that periodontal pathogens have a depth of penetration till the cemento-dentinal junction.¹ Hence they advocated removal of all the diseased cementum. However, in the same year, Nakib et al., demonstrated that endotoxin adherence to the tooth surface did not involve the cementum at all even in healthy cases and binding of the endotoxin to the root surface appeared to be weak.² The authors did not endorse the complete removal of cementum. Therefore, during root planing, it is advised to selectively remove only a thin layer of cementum to avoid unintentionally creating a rough surface.

The standard practice after root planing is to check the relative smoothness of the tooth surface with the tip of the explorer and assess through tactile sensation. By visual inspection of tooth surfaces treated in vivo or in vitro, only gross characteristics of the effects of various instruments can be observed. The use of scanning electron microscopy has also given valuable information regarding root surface morphology following periodontal instrumentation. This paved way for the Loss of Tooth Substance Index by Lie and Meyer in the year 1977.⁴

According to the results of this study, highest roughness scores were observed in the group that used diamond coated piezo tips. This is in agreement with numerous other studies reporting that diamond coated tips remove considerable amounts of tooth surface compared to other modalities.^8,9

One of the studies revealed similar results using both confocal microscopy as well as scanning electron microscopy.¹⁰ Different grains of diamond coated tips including micro-ultrasonic tips (30 μ) were used and still proved to produce greater surface roughness than other inserts and instruments.¹¹ Several studies showed that diamond coated tips increase roughness of surface microtopography in addition to effective removal of calculus.^12,13

However, Eick S et al., observed that treatment of root surfaces with conventional Gracey curettes followed by subsequent polishing with diamond-coated curettes may result in a root surface which provides favourable conditions for the attachment of PDL fibroblasts without enhancing microbial adhesion.¹⁴ This could be due to the use of manual diamond-coated instrumentation, wherein forces may not be as destructive as when used with power-driven instruments.

In the study by Schlageter et al., comparison was done with Gracey curettes, piezo-driven tips as well as two types of diamond tips - fine and coarse.¹⁵ Results revealed that fine tips produce as smooth a surface as other groups, while coarse tips produce greater root surface roughness as compared to the finer grit tips.

Furthermore, the results of this study indicate that both the manual Gracey curette and Ultrasonic scaler tip provide statistically comparable outcomes in terms of root surface roughness, which is the least amongst the three groups.

Literature reveals varying results in terms of comparison between manual and power-driven ultrasonic instrumentation. Several studies indicate similar amounts of root surface roughness between use of curettes and other groups.^16-19

Some studies provide evidence of smoothest root surface delivered with hand instrumentation using curettes compared to instrumentation using ultrasonic tips.^20-22

However, in contrast to the above records, certain studies report that manual instrumentation with curettes can cause a rougher root surface and unwarranted removal of tooth surface in comparison to power-driven ultrasonic and piezo surgical tips.^23-27

In addition to the above, the wearing of tips need to be considered in terms of a clinical setup, as these can alter the outcome in root surface microtopography produced after the procedure.

The major limitations of this study include the lack of standardisation in terms of force and angulation of the instruments during instrumentation.

Within the limitations of this study, we infer that greater root surface roughness is produced when instrumenting with piezo-surgery driven diamond coated tips and a relatively similar result can be observed from manual instrumentation with Gracey curettes and power-driven ultrasonic scaler tips.

Conclusion

A smooth, hard and clean root surface after root planning is the expected outcome for any further periodontal therapy. Achieving this is of paramount importance for successful treatment. Both manual and power-driven instruments are currently in use, and the inference from this study is that diamond coated tips produce greater root surface roughness. Manual instrumentation with Gracey Curettes and power-driven instrumentation with ultrasonic tips produce a smoother root microtopography.

Clinicians can undertake a combination of hand and power-driven instrumentation based on what best suits the needs of that particular patient, noting the expected outcome of treatment and further treatment plan. Further large scale studies with standardised delivery methods are needed to confirm the results of this study.

Acknowledgements

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Conflict of interest

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