Er,Cr:YSGG Laser Application for the Treatment of Periodontal Furcation Involvements

Abstract

Objective: The purpose of this study was to evaluate the clinical use of an erbium, chromium: yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser in the management of root furcation involvements. Background data: It has been suggested that the use of laser radiation within the periodontal pocket may be effective in periodontal treatment. However, very limited data from clinical trials exist directly comparing the use of the Er,Cr:YSGG laser to conventional root planing. Materials and methods: Thirty patients with chronic periodontitis were recruited. A total of 128 teeth with degree II or III furcation involvement were included in a split-mouth design such that the teeth on one side of the mouth were established as Group A and treated with the Er,Cr:YSGG laser and the teeth on the other side were established as Group B and treated with manual subgingival debridement. Changes in probing depth (PD), bleeding on probing (BOP), clinical attachment loss (CAL), and visual analogue scale (VAS) pain scores were compared between Groups A and B and within individuals over time at 6 and 12 weeks after treatment, testing the null hypothesis that there would be no clinical difference between treatment modalities. Results: Both treatments significantly reduced the PD, CAL, and BOP in the diseased teeth with degree II or III furcation involvement. The reduction of PD and BOP at weeks 6 and 12 was significantly higher in Group A (laser treated) than in Group B. The VAS pain score was significantly lower in Group A than in Group B (p < 0.01). Conclusions: Pocket debridement with Er,Cr:YSGG laser is a safe, comfortable, and clinically effective means of subgingival debridement in periodontal therapy.

Introduction

Periodontal disease is one of the two most common diseases of the human oral cavity, and dental plaque microorganisms are its initiating factor.¹ The traditional treatment modality for periodontitis is scaling and root planing (SRP), which consists of debridement of contaminated root surfaces in an attempt to eliminate bacteria and their endotoxins from the cementum and from the adjacent periodontal tissues.² However, furcation involvement of the molars and premolars is frequently observed in individuals presenting with moderate-to-severe periodontitis, and it can greatly hinder the complete removal of the bacterial deposits when using conventional SRP.³ Due to the complex anatomical structure of the root furcation, deposited plaque and calculus are difficult to remove and can easily accumulate causing periodontal infections. In this way, different adjuvant therapies have been advocated in the treatment of periodontitis, and the use of laser radiation in periodontal therapy has become a topic of much interest.

The erbium, chromium: yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser has a wavelength of 2.78 μm, and most commercial units provide up to 6.5 W of power, enough for removal of tooth structure and cavity preparation in restorative dentistry.⁴ The wavelength of light energy provided by erbium lasers is highly absorbed by water so when the laser is directed at biological tissues, the water within the hard or soft tissues rapidly heats and turns into steam, producing an ablation of the tissue surface to a depth related to the laser wavelength and the water content of the tissue. However, the lower power settings of commercially available Er,Cr:YSGG lasers are suitable for soft tissue cutting and coagulation. Further, commercial versions of the Er,Cr:YSGG laser provide a cooling water spray that is directed with the laser, minimizing overheating of hard and soft tissues. During subgingival debridement with laser energy, it is hypothesized that the water spray will aid the physical separation of the plaque and calculus in the periodontal pocket, and it has been shown that high-speed jet flow facilitates fast cleaning and prevents the laser from causing thermal damage.^5,6 Recently, a series of studies have indicated that erbium lasers can be used as an effective therapy for removal of plaque, calculus, and diseased cementum.^7

–10 Er,Cr:YSGG therapy has also been demonstrated to have bactericidal effects on the surfaces of roots affected by periodontal disease¹¹ and to stimulate new bone formation in the furcation area in experimental periodontitis.¹²

To assess the clinical effect of the Er,Cr:YSGG lasers in the treatment of moderate-to-advanced root furcation lesions involved in chronic periodontitis, in this study, the clinical efficiency of an Er,Cr:YSGG laser was compared to that of conventional manual subgingival debridement in patients with chronic periodontitis.

Materials and Methods

Subject selection

Thirty-one patients were recruited from the Department of Periodontology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. The study was conducted in accordance with the ethical standards of the Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. Signed informed consent was obtained from all patients before the start of the treatment.

Inclusion criteria: (1) a clinical diagnosis of moderate-to-severe chronic periodontitis based on the new periodontal disease classification system released in 1999¹³; (2) the extent of the periodontitis included at least 4 M in at least two dental quadrants where periodontal probing depths (PD) ≥4 mm in the area of the root furcations were associated with moderate (degree II) or severe (degree III) furcation involvement of the molars; (3) no fewer than 18 teeth remained in each patient's mouth; (4) no systemic diseases were present that would affect periodontal treatment; (5) female patients were not pregnant and had no intention of becoming pregnant during the study; (6) no history of smoking; and (7) no use of antibiotics during the month immediately before the study.

Study design

The study was performed according to a split-mouth design (Fig. 1). All patients who were candidates for the study were educated about dental health and supragingival scaling. One week later, an ultrasonic scaling instrument (Electro Medical Systems) was used to remove the subgingival calculus on all teeth in the mouth. All patients were re-examined 2 weeks later to record the PD measuring the distance in mm from the gingival margin to the bottom of the periodontal pocket at six sites (mesiofacial, midfacial, distofacial, mesiolingual, midlingual, and distolingual) around the perimeter of each tooth. Baseline values of PD, clinical attachment level [clinical attachment loss (CAL) in mm], and bleeding on probing (BOP) were recorded for every site.

FIG. 1.

Study design from screening to completion of the trial. After baseline treatment, screening, and periodontal examination, diseased teeth were randomly assigned to group A or B. Patients were treated with Er,Cr:YSGG laser or with hand instruments (Gracey curettes) for subgingival debridement of periodontal pockets and root furcations and then re-examined 6 and 12 weeks later. Clinical periodontal parameters of gingival BOP, PD, and CAL at each examination were obtained and analyzed. BOP, bleeding on probing; CAL, clinical attachment level; Er,Cr:YSGG, erbium, chromium: yttrium–scandium–gallium–garnet; PD, probing depth.

For the candidates who met all of the inclusion criteria and were recruited into the study, split-mouth treatment conditions were randomly assigned. Sites with moderate-to-advanced disease parameters (Class II and III furcation involvements with PD ≥4 mm) on one side of the mouth were considered Group A and treated with the Er,Cr:YSGG laser (BIOLASE Technology, Inc., San Clemente, CA), while the sites with these moderate-to-advanced disease parameters on the other side of the mouth were considered as Group B and treated with hand instruments (Gracey curettes). Assignment of diseased teeth on each patient's left or right side to Group A or B was determined by random number assignment (odd/even) using the Microsoft Excel software.

A commercially available Er,Cr:YSGG laser system (Millennium System; BIOLASE Technology, Inc.) with a 2.78 μm wavelength equipped with an RFPT 5–14 fiber optic tip of 14 mm in length and a tip diameter of 500 μm was used in the study. The parameters of the laser were set as follows: output power of 1.25 W, pulse mode H for soft and hard tissue with bell-shaped, asymmetrical pulses (pulse width 60 μs), and a pulse frequency of 30 Hz, using a water spray volume of 25 mL/min.

For all diseased teeth included in the split-mouth design, the fiber optic head was moved around the periodontal pockets and across the surface of the root furcations, while debris was washed out of the periodontal pockets with flowing water and collected by a separate vacuum system. No local anesthetic was given at any time. Treatments were rendered by two separate periodontists; one periodontist performed hand instrumentation for every subject and the other periodontist performed laser therapy for every subject.

A visual analogue scale (VAS) assessment was performed immediately after treatment.¹⁴ A 100 mm line was presented with its end-points representing “painless” and “severe pain.” The patient drew a perpendicular line to indicate the severity of pain he or she felt.

PD, CAL, and BOP of diseased teeth included in the split-mouth treatment design were recorded 6 and 12 weeks after treatment. To minimize variance in clinical probing data, all clinical measurements of diseased teeth in groups A and B were made by a single, well-trained, examiner using a Hu-Friedy PCP UNC 15 color-coded periodontal probe. The examiner was blinded to the treatment assignments.

Statistical analysis

Analyses were performed with a Statistical Analysis System (SAS 6.12; SAS Institute, Cary, NC) and clinical measurement data are expressed as mean ± standard deviation. PD, CAL, and BOP measurements made 6 or 12 months after laser or mechanical treatments were compared to baseline values in all diseased teeth using paired t-tests within each subject. The differences in variables between Group A and Group B were also compared directly at each time point using paired t-tests. Statistical significance was set at p < 0.05.

Results

General condition of subjects

Thirty-one patients with chronic periodontitis having bilateral molars with Class II or III furcation lesions and meeting all other criteria were included in the study. One patient was later excluded because that patient was given local infiltration anesthesia during treatment and could not complete the VAS. Diseased teeth in Group A (n _A = 63) were treated with an Er,Cr:YSGG laser and diseased teeth on the other side of the mouth in Group B (n _B = 65) were treated with hand instruments. Patients ages ranged from 24 to 72 years old (average 35.2 ± 9.8 years) and 17/30 were females. As shown in Table 1, the baseline clinical data showed no significant differences between Group A and Group B teeth. No adverse events were reported during the study.

Table 1.

Clinical Data for Diseased Teeth Treated in Group A and B (mm, Mean ± Standard Deviation)

Index/treatment	Baseline	6 weeks	d ^a	p^b	12 weeks	d ^a	p^b
PD
A (n = 63)	4.98 ± 0.69	3.84 ± 0.63	1.09 ± 0.69	<0.0001^†	3.53 ± 0.95	1.36 ± 0.84	<0.0001^†
B (n = 65)	5.08 ± 1.06	4.27 ± 0.94	0.80 ± 0.50	<0.0001^†	4.09 ± 1.21	0.96 ± 0.71	<0.0001^†
p ^c			0.0066^†			0.014^*
CAL
A (n = 63)	4.40 ± 1.12	3.49 ± 0.93	0.92 ± 0.60	<0.0001^†	3.18 ± 0.91	1.23 ± 0.64	<0.0001^†
B (n = 65)	4.37 ± 1.37	3.65 ± 1.36	0.69 ± 0.18	<0.0001^†	3.36 ± 1.03	1.02 ± 0.53	<0.0001^†
p ^c			0.20			0.19
BOP^d
A (n = 30)	0.77 ± 0.15	0.35 ± 0.14	0.41 ± 0.13	<0.0001^†	0.36 ± 0.13	0.40 ± 0.13	<0.0001^†
B (n = 30)	0.78 ± 0.13	0.43 ± 0.15	0.34 ± 0.08	<0.0001^†	0.45 ± 0.13	0.33 ± 0.11	<0.0001^†
p ^c			0.02^*			0.03^*

Designates mean change in measurement within each site.

Compared with baseline.

Comparison of the changes of both groups.

Proportion of teeth with BOP.

^*p < 0.05; ^† p < 0.01.

BOP, bleeding on probing; CAL, clinical attachment loss; PD, probing depth.

Clinical comparison of response to debridement with laser versus mechanical instrumentation

Following the split-mouth treatments of the diseased teeth, the treated teeth were clinically examined 6 and 12 weeks later to record PD, CAL, and BOP. The overall results are presented in Table 1.

For diseased molars with Class II or III furcation lesions and diseased sites with PD ≥4 mm at baseline, both treatment modalities were associated with inflammation reduction and periodontal tissue repair (Fig. 2). PD, CAL, and BOP in both groups were significantly decreased at week 6 and 12 after treatment compared with baseline (p < 0.01). The reduction of PD in the laser-treated group was greater than in the control group at both week 6 (p < 0.01) and week 12 (p < 0.05). CAL showed no significant difference between the two groups at week 6 or 12 (p > 0.05). The percentage of sites with demonstrated BOP in the laser-treated group (Group A) was significantly lower than the proportion with BOP in group B at week 6 and 12 (p < 0.05).

FIG. 2.

Pre- and postoperative clinical images of furcation involvements. (a) Preoperative; (b) after supra and subgingival ultrasonic scaling as the baseline; (c) 6 weeks after subgingival debridement; and (d) 12 weeks after subgingival debridement. Arrows indicate treated teeth in a single case. Both treatment modalities were associated with reduced gingival inflammation and improved gingival contour.

The number of sites in each group that presented with PD measurements of 3 mm or less was recorded at the 6- or 12-week follow-up examinations. Group A had 12 and 29 teeth dropping below the 3-mm pocket depth at 6 and 12 weeks after the treatment, respectively. Group B had fewer teeth dropping below the 3-mm pocket depth, the number being 5 and 16 for week 6 and 12, respectively.

Comparison of VAS evaluation between two groups of teeth

The VAS value for the laser-treated group (3.17 ± 0.79) was significantly lower than for the manually treated group (6.80 ± 1.21; p < 0.01).

Discussion

The concave anatomy of the root furcation renders it vulnerable to dental plaque accumulation, which can lead to development of a furcation lesion, periodontal pockets, and alveolar bone resorption. The disease process hastens as the lesion deepens and, with incomplete treatment, may cause loosening or loss of teeth. The development and prognosis of root furcation lesions are closely related to the anatomical and structural features of the roots of the involved teeth such as the length of the root trunk, the angle and width at the bifurcation, and the concave shape of the surface of the root.¹⁵

The beginning of periodontal treatment is the most critical stage in the treatment of periodontal disease, and scaling, curettage, and subgingival debridement are the most important parts. During conventional periodontal treatment after supragingival calculus is removed with a scaler or ultrasonic device, a variety of sharp curettes allow the clinician to reach below the gingival margin to remove subgingival calculus and to remove the contaminated cementum surface of the root in a process called root planing. Root planing with curettes may inadvertently damage the root surface creating areas for bacterial accumulation or may completely remove cementum exposing the underlying dentinal tubules, which leads to sensitivity during and after treatment. Even though curettes can remove the unhealthy granulation tissue from the periodontal pocket, scraping and stretching of the soft tissue during treatment may induce the release of histamine and cause bleeding, edema, and pain. Also, therapeutic efficiency is limited for some anatomical locations deep within the periodontal pocket (such as the root furcation) that cannot readily be reached by traditional instruments. Longitudinal studies of periodontal therapy have confirmed that the prognosis for diseased teeth with furcation lesions is worse following traditional scaling.¹⁶ According to a previous report,¹⁷ 58% of first molars have root furcation entrances smaller than 0.75 mm. The width of the blade of common subgingival curettes is 0.75 mm making it difficult to enter and clean the furcation entrance with these hand instruments. Further, the hard blade of the curettes is very different in shape from the concave root surface at the furcations. For this reason, even with open curettage, it is almost impossible to completely remove the dental calculus and plaque from sites with complex root anatomy using this kind of instrument. However, the removal of the calculus and infected cementum is a necessary precondition for a satisfactory outcome in periodontal therapy.^18,19

Periodontal laser therapy, as a supplementary means of traditional periodontal treatment, has seen widespread application. In several in vitro studies, Er,Cr:YSGG lasers were proven to be effective in removing calculus without causing detrimental effects to the surfaces of the roots.²⁰ They have also been found to exert bactericidal activity in root canals in addition to the mechanical removal of biofilm.^20,21 Moreover, the use of Er,Cr:YSGG laser has been shown to stimulate bone formation in the furcation area following subgingival treatment with the laser, indicating it may facilitate post-therapy bone healing.¹² However, few studies have been done to assess the clinical application of Er,Cr:YSGG laser in basic treatment of periodontal disease.

The current study has shown that pocket debridement using both laser and conventional methods can significantly decrease PD, CAL, and BOP in periodontal patients (p < 0.01, compared to baseline). The laser treatment showed better effects on PD changes at week 6 (p < 0.01) and week 12 (p < 0.05) and a greater reduction in BOP (p < 0.05) compared to hand instrumented sites in the same patient. No significant difference was observed in CAL between the two groups (p > 0.05). For this reason, it was here concluded that both Er,Cr:YSGG lasers and manual scaling could exert a notable therapeutic effect in periodontal pocket debridement, and laser treatment provided a better clinical outcome than did manual instrumentation. No short-term effect on periodontal regeneration was observed. Schwarz et al. reported that 6 months after treatment, both laser and hand-instrumented groups showed significant improvement in clinical parameters compared to baseline, and the improvement of BOP and CAL in a laser-treated group was better than in a hand-instrumented group.²² Such results were generally consistent with observations made in the present study. In a previous study, results showed that for sites with baseline PD ≥6 mm, the reduction of PD at week 12 after treatment with the Er,Cr:YSGG laser was better than measured in control sites.²³ Together, these reports, including the present data, suggest that the Er,Cr:YSGG laser can provide a clinically effective outcome at complex anatomical sites such as deep periodontal pockets and root furcations.

An additional advantage of Er,Cr:YSGG lasers in periodontal pocket debridement is that thermal injury can be avoided (e.g., carbonization of root surface or fusion) so long as sufficient water mist cooling is used.²⁴ This helps prevent patients from feeling uncomfortable. An international VAS was used in this study to evaluate the degree of pain. In the split-mouth design used in this study where the initial degree of periodontitis severity on both sides was comparable, results showed that the VAS value for laser-treated and manually treated groups was 3.17 ± 0.79 and 6.80 ± 1.21, respectively, demonstrating significantly less pain perception for laser-treated teeth (p < 0.01). This was consistent with most previous reports^25,26 and suggests that the use of Er,Cr:YSGG may significantly increase compliance with periodontal treatment by reducing pain during periodontal treatment.

The Er,Cr:YSGG laser used in the study had an RFPT (Radially Firing Perio Tip) optical head specifically designed for dentistry. It allows vertical and radial (360°) excitation synchronously. The radial and vertical excitation account for 85% and 15% of the total excitation output, respectively. This output design can enable better coverage of the lesion within the periodontal pocket while treating the root furcation even when the angulation of the vertically directed laser cannot be made near tangential to the surface of the root. The laterally directed laser energy from the tip helps to ensure removal of inflammatory plaque while enhancing the safety of operation. While the design of the present study did not allow meaningful differential analysis between buccal, lingual, mesial, or distal furcations, given the simultaneous vertical and radial lesion coverage during instrumentation with the RFPT, it will be interesting to directly compare manual instrumentation outcomes with this laser therapy in future studies by us and others.

Conclusions

In this study, data indicated that the Er,Cr:YSGG laser was a safe, comfortable, and effective treatment for periodontal pocket debridement at root furcations and in deep periodontal pockets in patients with chronic periodontitis. While the Er,Cr:YSGG laser was clinically more effective than conventional hand instrumentation, it was also successful in initial periodontal therapy because it involved less pain and promoted good patient compliance. Long-term follow-up observations are warranted for further assessment of Er,Cr:YSGG lasers in periodontal clinical application.

Footnotes

Acknowledgments

This study was supported by the fund of Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine (2012-08).

Author Disclosure Statement

No competing financial interests exist.

References

Saini

, Marawar

, Shete

, Saini

. Periodontitis, a true infection. J Glob Infect Dis, 2009; 1:149–150.

Sanz

, Alonso

, Carasol

, Herrera

, Sanz

. Nonsurgical treatment of periodontitis. J Evid Based Dent Pract, 2012; 12(3 Suppl.):76–86.

Flemmig

, Beikler

. Control of oral biofilms. Periodontol 2000, 2011; 55:9–15.

Romanos

. Current concepts in the use of lasers in periodontal and implant dentistry. J Indian Soc Periodontol, 2015; 19:490–494.

Cercadillo-Ibarguren

, Espana-Tost

, Arnabat-Dominguez

, Valmaseda-Castellon

, Berini-Aytes

, Gay-Escoda

. Histologic evaluation of thermal damage produced on soft tissues by CO₂, Er,Cr:YSGG and diode lasers. Med Oral Patol Oral Cir Bucal, 2010; 15:e912–e918.

Stubinger

. Advances in bone surgery: the Er:YAG laser in oral surgery and implant dentistry. Clin Cosmet Investig Dent, 2010; 2:47–62.

Eberhard

, Ehlers

, Falk

, Acil

, Albers

, Jepsen

. Efficacy of subgingival calculus removal with Er:YAG laser compared to mechanical debridement: an in situ study. J Clin Periodontol, 2003; 30:511–518.

Gaspirc

, Skaleric

. Morphology, chemical structure and diffusion processes of root surface after Er:YAG and Nd:YAG laser irradiation. J Clin Periodontol, 2001; 28:508–516.

Noori

, Fekrazad

, Eslami

, Etemadi

, Khosravi

, Mir

. Comparing the effects of root surface scaling with ultrasound instruments and Er,Cr:YSGG laser. Lasers Med Sci, 2008; 23:283–287.

10.

Verma

, Maheshwari

, Singh

, Chaudhari

. Laser in dentistry: an innovative tool in modern dental practice. Natl J Maxillofac Surg, 2012; 3:124–132.

11.

De Andrade

AKP

, Feist

, Pannuti

, Cai

, Zezell

, De Micheli

. Nd:YAG laser clinical assisted in class II furcation treatment. Lasers Med Sci, 2008; 23:341–347.

12.

Pavone

, Perussi

, de Oliveira

, et al. Effect of Er,Cr:YSGG laser application in the treatment of experimental periodontitis. Lasers Med Sci, 2015; 30:993–999.

13.

1999 International Workshop for a Classification of Periodontal Diseases and Conditions. Papers. Oak Brook, Illinois, October 30–November 2, 1999. Ann Periodontol, 1999; 4:1–112.

14.

Huskisson

. Measurement of pain. Lancet, 1974; 2:1127–1131.

15.

Do Vale

, Del Peloso Ribeiro

, Bittencourt

, Nociti

Jr , Sallum

, Casati

. Radiographic characteristics of furcation involvements in mandibular molars as prognostic indicators of healing after nonsurgical periodontal therapy. J Am Dent Assoc, 2009; 140:434–440.

16.

Wang

, Burgett

, Shyr

, Ramfjord

. The influence of molar furcation involvement and mobility on future clinical periodontal attachment loss. J Periodontol, 1994; 65:25–29.

17.

Bower

. Furcation morphology relative to periodontal treatment. Furcation entrance architecture. J Periodontol, 1979; 50:23–27.

18.

Bowers

, Schallhorn

, McClain

, Morrison

, Morgan

, Reynolds

. Factors influencing the outcome of regenerative therapy in mandibular Class II furcations: part I. J Periodontol, 2003; 74:1255–1268.

19.

Cattabriga

, Pedrazzoli

, Wilson

Jr . The conservative approach in the treatment of furcation lesions. Periodontol 2000, 2000; 22:133–153.

20.

Ting

, Fukuda

, Watanabe

, Aoki

, Sanaoka

, Noguchi

. Effects of Er,Cr:YSGG laser irradiation on the root surface: morphologic analysis and efficiency of calculus removal. J Periodontol, 2007; 78:2156–2164.

21.

Yavari

, Rahimi

, Shahi

, et al. Effect of Er, Cr: YSGG laser irradiation on Enterococcus faecalis in infected root canals. Photomed Laser Surg, 2010; 28(Suppl. 1):S91–S96.

22.

Schwarz

, Sculean

, Georg

, Reich

. Periodontal treatment with an Er: YAG laser compared to scaling and root planing. A controlled clinical study. J Periodontol, 2001; 72:361–367.

23.

, Shu

. Clinical application of periodontal initial treatment with Er,Cr:YSGG laser for patients with chronic periodontitis. J Oral Sci Res, 2014; 30:235–237.

24.

Sasaki

, Aoki

, Masuno

, Ichinose

, Yamada

, Ishikawa

. Compositional analysis of root cementum and dentin after Er:YAG laser irradiation compared with CO₂ lased and intact roots using Fourier transformed infrared spectroscopy. J Periodont Res, 2002; 37:50–59.

25.

Eren

, Altinok

, Ertugral

, Tanboga

. The effect of erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser therapy on pain during cavity preparation in paediatric dental patients: a pilot study. Oral Health Dent Manag, 2013; 12:80–84.

26.

Ryu

, Yoo

, Kim

, et al. Laser modulation of heat and capsaicin receptor TRPV1 leads to thermal antinociception. J Dent Res, 2010; 89:1455–1460.