A Comparative Evaluation of the Efficacy of Diode Laser as an Adjunct to Mechanical Debridement Versus Conventional Mechanical Debridement in Periodontal Flap Surgery: A Clinical and Microbiological Study

Abstract

Background and objectives: Research has shown that mechanical methods of periodontal therapy alone may fail to eliminate the tissue-invasive pathogenic flora; therefore, considerable attention has been given to adjunctive antimicrobial measures. The purpose of this study is to evaluate the efficacy of diode laser as an adjunct to mechanical debridement in periodontal flap surgery, on the basis of clinical parameters and microbiological analysis. Materials and methods: A total of 30 patients with generalized chronic periodontitis with probing depth >5 mm after phase I therapy were included in the study. Diode laser was used as an adjunct to open flap debridement (test) as compared with conventional flap surgery (control) in a split-mouth study design. Clinical parameters (plaque and gingival index, probing depth and relative clinical attachment level) and subgingival plaque samples of test and control groups were analyzed at baseline and 3 months post-therapy. Visual analogue scale (VAS) was used to determine patient discomfort intraoperatively and after 1 week. Results: The difference between the clinical parameters in the test and control groups did not reach a statistical significance. However, there was a statistically significant reduction in colony forming units (CFU) of obligate anaerobes in the test group as compared with the control group. The diode laser was well tolerated by the patients, as determined by the VAS. Conclusions: The bactericidal effect of the diode laser was clearly evident by greater reduction of CFU of obligate anaerobes in the test group than in the control group.

Introduction

P eriodontitis is the result of complex interrelationships between infectious agents such as bacteria and host factors.^1,2 It is universally accepted that periodontal disease is the result of mixed bacterial infections that require the participation of a very limited number of the members of the anaerobic microbiota inhabiting the subgingival region, and results in the destruction of the supporting structures of the teeth.^3,4

Most conventional methods used to treat the disease involve disruption of the biofilm by mechanical removal of subgingival plaque and, sometimes, the adjuvant use of antimicrobial agents and mechanical surgical debridement of pocket and root surfaces damaged as a result of periodontal disease. An alternative (ecological) approach would be to alter the environment of the pocket to prevent the growth of the putative pathogens, as suggested by Marsh (ecological plaque hypothesis).⁵

The nonsurgical therapy leads to resolution of inflammation, reduction in bacterial load, and reduction in probing pocket depth. However, the complete removal of bacterial toxins from the root surfaces⁶ in the deep periodontal pockets is not always achieved with nonsurgical therapy.⁷ Instrumentation is not possible in inaccessible areas such as furcation, grooves, and concavities.⁸ Also, according to Schenk et al.,⁹ sonic and ultrasonic instrumentation does not lead to killing of periopathogens. These instruments help to reduce the bacterial load by mechanical removal of plaque and calculus.

Thus, surgical therapy performed in cases with persistent inflammation, deeper pockets, class II and III furcation defects, and intrabony defects provides better accessibility to root surfaces as well as osseous defects. However, periopathogens persist in the mixed-species plaque biofilm on tooth surfaces, adhere to and enter the epithelial cells, and are tissue invasive in nature.¹⁰ These are sources for recolonization and reinfection. The limitations of the conventional therapy have probed us to implement the use of adjunctive antimicrobial measures.

Laser-assisted periodontal therapy has attracted attention recently as a potential alternative or adjunct to conventional mechanical debridement.¹¹ Carbon dioxide (CO₂) laser, neodymium doped:yttrium-aluminum-garnet (Nd:YAG) laser, and diode and erbium-doped:yttrium-aluminium-garnet (Er:YAG) laser have been used in the therapy of periodontal pocket for hard tissue as well as soft tissue management.¹² A part of the laser energy scatters and penetrates during irradiation into periodontal pockets. The attenuated laser at a low energy level might then stimulate the cells of surrounding tissue resulting in reduction of the inflammatory conditions (Shimizu et al.),¹³ in cell proliferation (Quadri et al.),¹⁴ and in increased flow of lymph (Shimotoyodome et al.),¹⁵ improving the periodontal tissue attachment and possibly reducing postoperative pain.

Diode laser has a wave length of 810 nm or 910–980 nm, which does not interact with dental hard tissues. Therefore, the laser is an excellent soft tissue surgical laser, indicated for cutting and coagulating gingiva and oral mucosa, and for soft tissue curettage or sulcular debridement. It also has a bactericidal effect.¹⁶ The purpose of this study was to evaluate the adjunctive effects of the diode laser in open flap debridement as compared with the conventional mechanical debridement as assessed by clinical and microbiological parameters.

Materials and Methods

Thirty patients were selected from the outpatient department of the Department of Periodontology and Oral Implantology of M.A. Rangoonwala College of Dental Sciences and Research Centre, Pune, India. The study was approved by the Local Ethical Committee (Protocol number MARDC/2008/P2). The study was explained to all the patients and an informed consent was taken from all the patients. Patients 30–50 years of age diagnosed with chronic periodontitis with probing pocket depths ≥5 mm after phase I therapy were included in the study. Smokers, pregnant women and lactating mothers, diabetic patients, and patients with a history of administration of antibiotics 3 months prior to their first visit were excluded from the study.

Patients with persistent probing pocket depth ≥5 mm underwent access flap surgery 4 weeks after phase I therapy. As this was a split-mouth study, patients with bilateral periodontal pockets in the anterior sextant of either maxilla or mandible were selected for the study. Patients with bony architecture where regenerative or resective surgeries were needed were not included in this study. Hence, only single-rooted teeth with horizontal bone loss were included in this study.

Measurements (clinical parameters)

Plaque index (PI)¹⁷ (Silness and Loe) and gingival index¹⁸ (GI) (Loe and Silness) were calculated at the baseline.

Stents were prepared to standardize the probe angulation and the reference point. The same stent was used for the follow-up measurements after 3 months.

The site with deepest probing pocket depth from the test and control groups was used for measuring all the parameters. Probing depth (PD) and relative clinical attachment level (CAL) were measured with the help of UNC 15 probe and acrylic stent.

Microbial sampling

Microbiological analysis for the colony forming units (CFU) of obligate anaerobes was performed in 10 randomly selected patients. Subgingival plaque samples were collected from the deepest pocket in the test and control site with the help of paper points at baseline and at 3 months. The plaque samples were transported in Robertson's cooked meat media to the microbiology laboratory within 1 h of collection. Samples were labeled and processed immediately. CFU of obligate anaerobes were calculated by: \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document}\begin{align*}{\rm y} \times 10^{- {\rm d}} \times 1 / {\rm v}\end{align*}\end{document}

where d=dilution plated, v=volume plated, and y=colony count on the plates (between 30 and 300)

Surgical protocol

The surgical sites were randomly allocated to test and the control groups. Conventional access flap surgery with mechanical debridement was performed on the control side. The test site included use of diode laser as an adjunct to mechanical debridement. Both the procedures were performed during the same sitting. Diode laser (Sunny Laser®) with a wavelength of 980 nm and a power setting of 2.5 W was used in continuous, contact mode with the help of a flexible fiberoptic delivery system (laser dose, 50 J/cm²). The fiber was used in a “brush stroke” motion on the undersurface of the flap to remove the pocket lining.

Postoperative care

Patients were given routine postoperative instructions. Antibiotics were not prescribed, as they would alter the flora and modify the effect of diode laser.

Visual analogue scale (VAS)

The intensity of pain experienced by the patient during the treatment and 1 week postoperatively was analyzed with the help of a VAS.¹⁹ This scale had a marking from 0 to 10, with 0=no pain, 1–3=slight pain, 4–6=moderate pain, and 7–10=severe pain. Patients were told to rate the intensity of pain on a scale of 0 to 10.

Patients were kept on a maintenance protocol. At 3 month follow-up, clinical and microbiological parameters were analyzed for test and control sites.

Statistical analysis

The absolute change in each periodontal index at 3 month follow-up with respect to baseline was calculated using the formula: (postoperative index – preoperative Index).

The statistical significance of several periodontal indices studied between two study groups was tested using the Mann–Whitney U test. In each study group, the intragroup analysis of baseline and 3 month follow-up indices was tested using Wilcoxon's signed-rank test, the statistical analysis tool for paired data.

A p value<0.05 was considered statistically significant. The entire data were analyzed using Statistical Package for Social Sciences (SPSS version 11.5) for MS Windows.

Results

The study included 30 patients with generalized chronic periodontitis within a range of 30–50 years of age, with a mean age of 41.4 years.

Intragroup comparison

The changes in the clinical and microbiological parameters from baseline to 3 months within control and test group are described.

The mean and standard deviation values for PI, GI, PD, and relative CAL at the baseline and at 3 months after surgery of control and test groups are shown in Table 1.

Table 1.

Intragroup Comparison of Periodontal Parameters Studied

Groups and parameters	Day 0 (n=30)	Day 90 (n=30)	p Value	Significance
Test group
Plaque index	0.54 (0.45)	0.29 (0.43)	0.052	Not sig
Gingival index	1.09 (0.75)	0.30 (0.47)	0.001	Sig
Probing depth	6.03 (1.22)	2.97 (0.72)	0.001	Sig
Clinical attachment level	11.07 (1.57)	9.70 (1.62)	0.001	Sig
Control group
Plaque index	0.55 (0.46)	0.30 (0.44)	0.077	Not sig
Gingival index	1.07 (0.77)	0.56 (0.62)	0.001	Sig
Probing depth	5.80 (1.19)	3.00 (0.95)	0.001	Sig
Clinical attachment level	11.5 (1.97)	9.80 (1.77)	0.001	Sig

The values of PI in the control group were 0.55±0.46 at the baseline and 0.30±0.44 at 3 months. The values of PI in the test group were 0.54±0.45 at the baseline and 0.29±0.43 at 3 months. This difference was also not found to be statistically significant (p value 0.077 and 0.052).

At 3 months, the GI and PD showed statistically significant decrease in both the groups and there was statistically significant gain in CAL in both the groups.

The GI decreased from 1.07±0.77 to 0.56±0.62 in the control group and from 1.09±0.75 to 0.30±0.47 in the test group after 3 months. The difference was statistically significant for both the groups (p value 0.001).

There was reduction in PD from 5.80±1.19 mm to 3.00±0.95 mm in the control group at 3 months. The PD decreased from 6.03±1.22 to 2.97±0.72 mm at 3 months in the test group. The difference was statistically significant with a p value of 0.001 in both the groups.

The mean relative CAL was 11.5±1.97 and 11.07±1.57 mm in the control and test group, respectively, at the baseline. At 3 months, the mean relative CAL was 9.80±1.77 and 9.70±1.62 mm in the control and test group, respectively, thus showing statistically significant gain in CAL compared to baseline in both groups (p value 0.001).

Table 2 shows the mean values of VAS of the test and the control groups recorded intraoperatively and after 1 week.

Table 2.

Intragroup Comparison of Visual Analogue Scale (VAS)

Groups and parameters	Intraop (n=30)	1 week postop (n=30)	p Value	Significance
Test group
VAS	1.90 (0.96)	1.83 (1.23)	0.713	Not sig
Control group
VAS	1.93 (0.91)	1.80 (0.85)	0.417	Not sig

The mean intraoperative value of VAS was 1.93±0.91 and 1.80±0.85 at 1 week in the control group. The mean intraoperative value of VAS was 1.90±0.96 and 1.83±1.23 at 1 week in the test group. The difference was not found to be statistically significant (p value 0.417 and 0.713).

Table 3 shows mean values of CFU at baseline and 3 months for the test and control groups.

Table 3.

Intragroup Comparison of Colony Forming Units (CFU)

Groups and parameters	Day 0 (n=10)	Day 90 (n=10)	p Value	Significance
Test group
CFU (per mL)	3.47×10⁴ (3.00×10⁴)	3.01×10³ (9.5×10³)	0.007	Sig
Control group
CFU (per mL)	4.09×10⁴ (2.72×10⁴)	7.07×10³ (4.9×10³)	0.005	Sig

The mean CFU of obligate anaerobes in the control group decreased from 4.09×10⁴±2.72×10⁴ to 7.07×10³±14.9×10³ CFU/mL, which was statistically significant (p value 0.005). The mean CFU of obligate anaerobes in the test group decreased from 3.47×10⁴±3.00×10⁴ to 3.01×10³±9.5×10³ CFU/mL, which was also statistically significant (p value 0.007).

Intergroup comparison

The comparison of mean values of PI, GI, PD, and relative CAL in the control and the test groups are demonstrated in Table 4.

Table 4.

Intergroup Comparison of Periodontal Parameters Studied

Parameters	Test group (n=30)	Control group (n=30)	p Value	Significance
Plaque index
Day 0	0.54 (0.45)	0.55 (0.46)	0.892	Not sig
Day 90	0.29 (0.43)	0.30 (0.44)	0.929	Not sig
Change (Day 0 – Day 90)	0.25 (0.62)	0.25 (0.64)	0.944	Not sig
Gingival index
Day 0	1.09 (0.75)	1.07 (0.77)	0.938	Not sig
Day 90	0.30 (0.47)	0.56 (0.62)	0.105	Not sig
Change (Day 0 – Day 90)	0.79 (0.64)	0.51 (0.63)	0.110	Not sig
Probing depth
Day 0	6.03 (1.22)	5.80 (1.19)	0.291	Not sig
Day 90	2.97 (0.72)	3.00 (0.95)	0.931	Not sig
Change (Day 0 – Day 90)	3.07 (1.41)	2.80 (1.03)	0.778	Not sig
Rel. clin. att. level
Day 0	11.07 (1.57)	11.5 (1.97)	0.716	Not sig
Day 90	9.70 (1.62)	9.80 (1.77)	0.815	Not sig
Change (Day 0 – Day 90)	1.37 (1.29)	1.70 (1.53)	0.292	Not sig

The difference between PI, GI, and PD reduction and gain in CAL between the control and test groups at 3 months was not statistically significant.

Table 5 shows comparison of VAS values in the control and test groups.

Table 5.

Intergroup Comparison of Visual Analogue Scale (VAS)

Parameters	Test group (n=30)	Control group (n=30)	p Value	Significance
VAS
Intraoperative	1.90 (0.96)	1.93 (0.91)	0.903	Not sig
1 week postoperatve	1.83 (1.23)	1.80 (0.85)	0.596	Not sig
Change (1 week – intraoperative)	0.07 (0.87)	0.13 (0.82)	0.900	Not sig

The difference between VAS between the control and test groups was also not statistically significant intraoperatively (p value 0.903) and at 1 week (p value 0.596).

Table 6 demonstrates the comparisons in the mean values of CFU in the control and test groups. The mean values of CFU at baseline between the two groups were not significantly different (p value 0.481). However, the mean value of CFU at 3 months in the test group was significantly lower than in the control group (p value 0.043).

Table 6.

Intergroup Comparison of Colony Forming Units (CFU)

Parameters	Test group (n=10)	Control group (n=10)	p Value	Significance
CFU (per mL)
Day 0	3.47×10⁴ (3.0×10⁴)	4.09×10⁴ (2.7×10⁴)	0.481	Not sig
Day 90	3.01×10³ (9.5×10³)	7.07×10³ (14.9×10³)	0.043	Sig
Change (Day 90 –Day 0)	3.17×10⁴ (2.7×10⁴)	3.38×10⁴ (1.9×10⁴)	0.853	Not sig

Therefore, the results of the study show that there was no clinical relevance when the clinical parameters were compared in the control and test groups. However, there was a statistically significant reduction in CFUs of obligate anaerobes in the test group as compared with control group.

Discussion

Successful periodontal therapy depends on anti-infective procedures aimed at eliminating or suppressing pathogenic organisms found in dental plaque associated with the tooth surface and within other niches in the oral cavity.²⁰ Nonsurgical mechanical therapy alone may not effectively eliminate the periodontal disease completely, particularly in deep pockets.²¹ Hence, surgical therapy is performed, which provides improved visualization of the root surface and defects.

Soft tissue lasers such as diode and Nd:YAG have the potential for curettage of pocket wall and disinfection of periodontal pockets.^12,22 Er:YAG laser can be used for both soft and hard tissue debridement. A search of literature reviews revealed very few reports of the use of CO₂ and Er:YAG lasers during surgical pocket therapy. However, there are no reports of the use of diode laser as an adjunct to mechanical debridement in access flap surgery, although it is the most commonly used laser. The adjunctive effects of diode laser in open flap debridement have been evaluated in this study based on clinical and microbiological parameters.

In the present study, PI was used to monitor the oral hygiene status of the patients. The results demonstrate that there was no statistically significant difference in the PI at baseline and at 3 months in the control and the test group. The PI score was consistently <1, suggesting maintenance of fair oral hygiene by the patients throughout the study.

On the other hand, GI decreased significantly from baseline to 3 months in the control and the test groups. This suggests the effectiveness of access flap surgery in reducing the signs of inflammation caused by effective removal of calculus and infected granulation tissue.²³

A VAS was used to determine the pain perception by the patient during the procedure and 1 week postoperatively. There was no statistically significant difference in the readings of VAS in both the groups, indicating that the level of patient comfort was similar in both groups. The use of diode laser as an adjunct to mechanical debridement neither led to postoperative complications nor to delayed healing. This indicates that diode laser did not seem to have any detrimental effect when employed in conjunction with periodontal surgery. According to Chow et al.,²⁴ laser induces inhibitory effects on the peripheral nerves by slowing the conduction velocity (CV) and/or reducing the amplitude of compound action potentials.

Centty et al.²⁵ used CO₂ laser (8 W and 20 Hz) on the outer and inner aspects of the mucoperiosteal flap. CO₂ laser was found to increase the effectiveness of periodontal therapy through epithelial exclusion technique. Gaspirc et al.²⁶ reported the long-term clinical outcome comparing the Er:YAG laser-assisted periodontal flap surgery with conventional treatment using the modified Widman flap procedure. In this investigation, the reduction of pocket depth and the gain of clinical attachment level were significantly greater in the laser group at 6–36 months after surgery.

Every laser has a different property and different tissue interactions, which depend upon the wavelength, power, waveform, tissue optical properties and tissue thermal properties.

Diode laser is an excellent soft tissue laser and is available in smaller cost-effective units. The radiation of diode laser shows greater absorption and less penetration than does Nd:YAG laser, especially in blood-rich tissue. Therefore, collateral damage with diode laser is less than with Nd:YAG or CO₂ laser.²⁷ The wavelength of diode laser is absorbed by the hemoglobin, which leads to tissue coagulation and formation of charred layer. Diode leads to thermocoagulation of the blood vessels, which is responsible for its hemostatic effect.²⁷ Thus, diode laser is an excellent soft tissue laser because of its tissue coagulating and hemostatic properties.

The laser mode of antisepsis has several potential advantages over traditional biochemical antibiotics. A therapeutic dose can be delivered to a greater depth locally and leaves no residual concentration.²⁸ Laser radiation affects equally extracellular and intracellular pigmented pathogens and can access other privileged sites such as calculus and dentinal tubules. Laser antisepsis has no known systemic side effects, resistances, or negative interactions with other modes of therapy.²⁸ Laser energy has the potential to breach the protective mechanisms of biofilms.²⁹

In the present study, there was a statistically significant reduction in the number of CFUs of anaerobes in the laser-treated group as compared with the control group. The wavelength of the diode laser was absorbed by protohemin and protoporphyrin IX pigments of the pigmented anaerobic periopathogens.³⁰ This led to vaporization of water and caused lysis of the cell wall of the bacteria, leading to cell death. It was effective against the tissue invasive periopathogens caused by absorption of laser energy up to 2±1 mm in the deeper tissues.³⁰

Since the mid-1990s, herpes viruses have emerged as putative pathogens in various types of periodontal disease.^31,32 Laser irradiation may also kill the herpes viruses in the tissues because of deeper penetration of laser energy. However, further studies are required to substantiate this hypothesis.

The disadvantages of the diode laser are ineffectiveness of calculus removal from the root surface and possibility of thermal damage to the bone in the presence of blood and at high power settings. However, thermal damage can be avoided with appropriate power settings and by using the laser intermittently, which would allow the tissues to cool. Castro et al.³³ evaluated effects of diode laser on root surface after using it as an adjunct to pocket therapy in a histological study. They did not observe any changes in the root surface caused by thermal damage.

It has been hypothesized that the charred layer that forms on the undersurface of the flap prevents the epithelial migration and promotes new attachment. Crespi et al.³⁴ provided histological evidence of formation of new cementum, periodontal ligament, and bone when CO₂ laser was used for debridement in class III furcation defects in dogs. Mizutani et al.³⁵ used Er:YAG laser for debridement during access flap surgery and noted that laser promoted more new bone formation.

The bactericidal effect of diode laser is evident from the reduction in the CFU of obligate anaerobes. The possible role of diode laser in killing viruses and promoting formation of new attachment can also be contemplated.

Conclusions

Diode laser was well tolerated by the patients and it demonstrated a significant bactericidal effect. Therefore, lasers can form an integral part of periodontal therapy in the future.

However, further longitudinal studies are required to evaluate the long-term effects of diode laser on clinical as well as microbiological parameters. The bactericidal effect of diode laser on specific microorganisms and viruses and time taken for microbial recolonization needs to be determined by further studies. Further animal studies are required to provide an insight into the healing and a possible role for diode laser in the formation of new attachment.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

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