Effect of laser application in the healing of intrabony defects treated with bioactive glass.

AIMS: Presence of bacteria within the environment of infrabony pockets affects healing during their treatment. Present investigation utilized a diode laser for pocket sanitization before the placement of bone biomaterial with the aim of enhancing the healing.
MATERIALS AND METHODS: Twelve patients with bilateral intrabony defects participated in a split-mouth study design. Control group received biomaterial application only after surgical debridement. Infrabony pockets in the test group were irradiated with 810-nm diode laser at 0.8 W, continuous wave for 20 s before surgical debridement and biomaterial application. Healing was assessed using clinical and radiologic parameters.
RESULTS: Control group showed mean probing depth (PD) reduction of 3.25 ± 0.62 at 3, 4.08 ± 0.90 mm at 6 months. 3.00 ± 0.73 at 3, 3.91 ± 0.66 mm at 6 months reduction in mean PD was seen in the test group (P < 0.001). No statistically significant differences between the groups were observed. A gain of 2.50 ± 0.67 at 3, 3.25 ± 0.62 mm at 6 months in relative clinical attachment level was seen in the control and of 2.33 ± 0.77 at 3, 3.16 ± 0.57 mm at 6 months in the test group (P < 0.001) without significant differences between groups. 1.33 ± 0.57 and 0.95 ± 0.68 mm hard-tissue fill (difference in the radiographic distance between cementoenamel junction and base of the intrabony defect pre- and post-operative) at 6 months was observed in the control and test groups, respectively (P < 0.001). Between groups differences (0.22 ± 0.24 mm) were not significant.
CONCLUSIONS: Similar reduction in soft- and hard-tissue parameters in both groups indicates that adjunctive pocket sanitization with diode laser did not improve the healing of intrabony defects treated with bioactive glass.

INTRODUCTION

For the treatment of periodontal osseous defects autogenous grafts, allografts, xenografts and alloplasts alone and in combination have been tried.[1] Ample availability and no risk of disease transfer make alloplasts the choice of biomaterials for the regeneration of intrabony defects. Bioactive glass a synthetic biomaterial composed of calcium salts, phosphate, sodium salts, and silicone is a novel synthetic biomaterial with the property of forming chemical bond with bone. The addition of silicon allows for the formation of a silica gel layer over the bioactive glass particles. This layer promotes the formation of a hydroxycarbonate-apatite layer onto which osteoblasts are said to proliferate and form bone.[2] Being osteoconductive in nature it also has osteostimulatory effect. In addition to the above properties, this material also exhibits antibacterial action against subgingival and supragingival bacteria.[3]

Healing of intrabony defects with or without grafting materials requires complete elimination of periodontal bacteria from within the environment of infrabony pockets. Mechanical therapy alone is not sufficient to completely remove bacteria from within the pocket environment. The presence of bacteria within the periodontal pocket affects the healing of osseous defects and hence the regeneration, resulting in reduced success.[45] To improve the healing of bony defects these biomaterials have often been combined with systemic antibiotics. However, repeated use of systemic antibiotics carries the risk of development of bacterial resistance. Limited potential of the conventional mechanical therapy in removing periopathogens, especially inside pocket wall and deep pockets prompted the adjunctive use of lasers for the treatment of chronic periodontitis[5] (CP). In the treatment of periodontitis and periimplantitis lasers have been employed for bacterial reduction, removal of pocket lining, calculus removal, and endotoxin removal with the aim of enhancing periodontal tissue healing.[6] Numerous studies utilizing adjunctive lasers in the nonsurgical treatment of CP have reported superior healing outcome (more probing depth [PD] reduction and attachment level gain) to no additional benefits. Moritz et al.[7] examined the antibacterial ability of diode laser in the treatment of periodontal pockets. At 6 months, bacterial reduction with diode laser therapy was significantly better than in the control group. Kamma et al.[8] examined the bactericidal and periodontal healing abilities of diode laser in the treatment of aggressive periodontitis. They compared scaling and root planing alone (SRP), diode laser (980 nm) treatment alone (LAS), and SRP combined with LAS (SRP + LAS) on clinical and microbial parameters. Levels of Porphyromonas gingivalis (P. g) and Treponema denticola showed a significant reduction after 6 months in the SRP + LAS group. PD reduction and clinical attachment level (CAL) gain also improved though, slightly in the SRP + LAS group. Effects of SRP plus saline irrigation and SRP with diode laser were compared by Kreisler et al.[9] on periodontal tissue healing. Additional use of diode laser showed significantly better periodontal tissue healing, i.e., higher reduction in tooth mobility and pocket depth with enhanced gain in CAL. The authors attributed this reduction in tooth mobility and PD to de-epithelization of periodontal pocket leading to connective tissue attachment.

In another study by Saglam et al.[10] combined application of diode laser and SRP in the treatment of CP led to a higher reduction in probing pocket depth (PPD) and more gain in CAL after 6 months compared to SRP alone. The gingival crevicular fluid matrix metalloproteinase-8 levels also improved in the laser group. Beneficial effects of lasers have also been seen in the treatment of periimplantitis. The use of laser in the treatment of periimplantitis (7-mm PPD, bleeding on probing, suppuration, and radiographic bone loss) as reported by Roncati et al.[11] showed a significant reduction in PPD and also improvement of the bone level after 5 years. In a clinical and microbiological study reported by Euzebio Alves et al.[12] adjunctive use of diode laser at 1.5 W for 20 s in two appointments at 1 week apart with SRP (test group) did not lead to additional PD reduction and attachment level gain. Furthermore, counts of black pigmented bacteria showed similar reduction in both the groups.

However, there are limited studies reporting the efficacy of adjunctive use of lasers in the surgical treatment of intrabony defects with grafting materials. Since healing of the osseous cavities is affected in the presence of bacteria in the periodontal tissues, laser pocket sanitization may enhance the osseous healing in combination with bioactive glass.

Therefore, with the aim to evaluate the periodontal tissue healing after combined use of bioactive glass and laser irradiation this study was undertaken.

MATERIALS AND METHODS

Twelve, 20–65 years old patients presenting with CP were selected from the Department of Periodontology after having signed an informed consent form. Ethical approval was obtained from the institution committee.

Following criteria's were established as follows: (1) no systemic disease that could influence the outcome of the therapy; (2) a good level of the oral hygiene, defined as a whole mouth plaque index (PI) <1; (3) compliance with the maintenance program; and (4) the presence of PD >6 mm following initial therapy and contralateral presence of radiographic intrabony defect. Intrabony defect was defined as osseous defect having depth of >2 ml with the most apical portion surrounded by three bony walls. Defects extending to buccal or lingual aspect of the root were also included.[1314]

There is around 2-mm connective tissue attachment between the bottom of sulcus and alveolar crest; therefore, defects not deeper than 2 mm were excluded. Nonsurgical periodontal treatment was completed.

Following parameters were recorded by the same examiner at baseline, 3 and 6 months using the University of North Carolina-15 mm probe.

Plaque index (PI) Silness and Loe 1967, gingival index (GI) Loe and Silness 1963[15] were recorded as the full mouth. PD (gingival margin as reference), gingival recession (GR) (apical end of the stent as reference), and relative clinical attachment level (RCAL) (apical end of the stent as reference) were site-specific. Acrylic plastic occlusal stent with grooves helped to guide the probe at the same location for measuring clinical parameters at different time intervals.

Intraoral periapical radiographs incorporating millimeter grid were taken with long cone paralleling technique. The difference in the radiographic distance between cementoenamel junction (CEJ) and base of the intrabony defect (BOD) pre- and post-operative was measured for recording hard-tissue fill. The grid has a box of 1 ml in height and width. Number of boxes exhibiting hard tissue fill were added to obtain data.

In a split-mouth study, design defects on one side of arch received laser application followed by biomaterial implantation (test group) and defects on other side received biomaterial implantation only (control group), randomly.

Surgical procedure

2% lidocaine containing 1:200,000 adrenaline was used to anesthetize operating field. After full thickness elevation from buccal and lingual aspects, osseous defect was debrided and root surfaces planed [Figures 1 and 2]. No conditioning of root surfaces was performed. In the control group, biomaterial (bioactive calcium phosphosilicate bone graft, nova bone, LLC Alachua FL 32615, USA) was placed into the osseous defects [Figure 3].

Figure 1

Deep osseous defect on distal aspect of 46 (control site)

Figure 2

Deep osseous defect (test site)

Figure 3

Bone biomaterial (putty form) (control site)

In the test group, pocket sanitization using diode laser (Picasso lite laser [AMD AMD LASERS, a company that builds dental laser technology. Alan Miller], wavelength 810 nm, maximum output power 2.5 W, pulse duration 30 ms) was performed before raising the flap. A power setting of 0.8 W, continuous wave for 20 s was used.[16] The fiber was placed on the tissue at the top of the periodontal pocket, directing the laser energy away from the tooth structure and was moved toward the bottom of the pocket [Figure 4]. The fiber was moved vertically and horizontally and contact was maintained with the soft-tissue lining the pocket. Once the lasing was complete, the same surgical procedure as described for the control group was performed [Figure 5].

Figure 4

Laser irradiation inside infrabony pocket on distal aspect of 46 (test site)

Figure 5

Biomaterial implanted into the osseous defect (test site)

Statistical analysis

Mean values are reported for each parameter. Posttreatment changes in clinical and radiographic parameters were analyzed using paired t-test (intra-group comparison). Comparison of clinical parameters between two groups at baseline, 3, and 6 months posturgery were performed utilizing the unpaired t-test. For all analysis, P < 0.05 was considered statistically significant.

RESULTS

All patients completed the study. A total of 24 intrabony (18 mandibular molars, four maxillary molars, and two mandibular premolars) defects underwent biomaterial implantation with or without laser irradiation.

Mean PI, GI scores at baseline, 3, and 6 months are shown in Table 1. At 3 months, GI score decreased significantly with further improvement at 6 months.

Table 1

Plaque index, gingival index values (mean±standard deviation, millimeter) at baseline, 3, and 6 months

	Baseline	3 months	6 months	Change from baseline to
				3 months (P)	6 months (P)
PI	0.72±0.16	0.95±0.14	0.91±0.18	0.21±0.18 (0.002)	0.18±0.23 (0.020)
GI	1.92±0.59	1.09±0.26	0.88±0.19	0.83±0.47 (0.001)	1.03±0.54 (0.001)

P<0.05 was considered statistically significant. PI – Plaque index; GI – Gingival index

Changes in PPD, relative clinical attachment level, and GR are reported in Table 2. PD reduced in both groups, from 7.58 ± 1.31 at baseline to 4.33 ± 0.88 at 3 months and 3.50 ± 0.52 at 6 months in the control group, and from 7.41 ± 1.16 at baseline to 4.41 ± 0.99 at 3 months and 3.50 ± 0.67 at 6 months in the test group (P < 0.001). There were no significant differences between the groups.

Table 2

Mean ± standard deviation (millimeter) clinical measurements at baseline, 3, and 6 months

	Baseline	3 months	6 months	Change from baseline to		P
				3 months	6 months
PPD
Control group	7.58±1.31	4.33±0.88	3.50±0.52	3.25±0.62	4.08±0.90	<0.001
Test group	7.41±1.16	4.41±0.99	3.50±0.67	3.00±0.73	3.91±0.66	<0.001
Difference	0.16±0.50 (NS)	0.08±0.38 (NS)	0.00±0.24 (NS)
GR
Control group	3.41±1.16	4.16±1.58	4.16±1.58	0.75±0.96	0.75±0.96	<0.021
Test group	3.33±0.98	4.00±1.20	4.00±1.20	0.66±0.65	0.66±0.65	<0.001
Difference	0.08±0.44 (NS)	0.16±0.57 (NS)	0.16±0.57 (NS)
RCAL
Control group	11.00±1.95	8.50±2.23	7.75±2.00	2.50±0.67	3.25±0.62	<0.001
Test group	10.83±1.69	8.50±1.88	7.66±1.61	2.33±0.77	3.16±0.57	<0.001
Difference	0.16±0.74 (NS)	0.00±0.84 (NS)	0.08±0.74 (NS)

P < 0.05 was considered statistically significant. PPD – Probing pocket depth; GR – Gingival recession; RCAL – Relative clinical attachment level; NS – Not significant

An increase in GR of 0.75 ± 0.96 and 0.66 ± 0.65 in the control and test groups, respectively, was observed at 3 months (P < 0.021), without further apical shift.

Relative clinical attachment level improved in both groups, from 11.00 ± 1.95 at baseline to 8.50 ± 2.23 and 7.75 ± 2.00 at 3 and 6 months, respectively, in control group, and from 10.83 ± 1.69 at baseline to 8.50 ± 1.88 at 3 months and 7.66 ± 1.61 at 6 months in the test group (P < 0.001) without significant differences between the groups.

CEJ-BOD distance was reduced in both groups, from 7.00 ± 1.95 at baseline to 6.08 ± 1.90 at 3 months and 5.66 ± 1.88 at 6 months in the control group, and from 6.58 ± 1.57 at baseline to 6.00 ± 1.73 and 5.62 ± 1.82 at 3 and 6 months, respectively, in the test group (P < 0.001) indicating hard-tissue fill. 1.33 ± 0.57 and 0.95 ± 0.68 hard tissue fill at 6 months was observed in the control and test groups, respectively. Between-group differences (0.22 ± 0.24) in hard-tissue fill were not statistically significant [Table 3].

Table 3

Cementoenamel junction-base of defect distance (mean±standard deviation)

	Baseline	3 months	6 months	Hard tissue fill at 3 months	Hard tissue fill at 6 months	P
CEJ-BOD distance
Control group	7.00±1.95	6.08±1.90	5.66±1.88	0.91±0.55	1.33±0.57	P<0.001
Test group	6.58±1.57	6.00±1.73	5.62±1.82	0.58±0.55	0.95±0.68	P<0.001
Difference	0.41±0.72 (NS)	0.08±0.74 (NS)	0.04±0.75 (NS)	0.15±0.18 (NS)	0.22±0.24 (NS)

P<0.05 was considered statistically significant. CEJ – Cementoenamel junction; BOD – Base of defect; NS – Not significant; mm – Millimeter

DISCUSSION

Marked reduction in PPD, a significant gain in RCAL and good radiographic hard-tissue fill [Figures 6–11] indicate that bioactive glass has the potential to promote healing. These improvements were similar in both the groups with no statistically significant differences indicating the adjunctive use of diode laser did not improve the healing.

Figure 6

Periapical radiograph, baseline (control site)

Figure 11

Six months periapical radiograph revealing stable level of gained hard tissue with no further fill compared to 3 months (test site)

Periapical radiograph, 3 months. Hard tissue fill in the apical third (control site)

Six months periapical radiograph showing further improvement in hard tissue fill (control site)

Three months periapical radiograph showing less hard tissue fill. Clinical healing was good. Tooth mobility reduced and 45 and 46 received splinted crowns (test site)

The healing response observed in the BG group in the present investigation is similar to earlier studies reported in the literature. Demir et al.[3] reported 3.29 mm reduction in PPD, 2.86 mm gain in CAL and 3.36 mm defect fill at the end of 9 months.

Low et al.[17] treated 17 defects on 12 patients and reported a 3.33-mm pocket reduction and a 1.92 mm attachment gain. Froum et al. 1998[18] compared BG graft material and OFD in the treatment of 59 intrabony defects in 16 patients and the results were evaluated at 12 months. The grafted group showed 4.26-mm pocket depth reduction, a 2.96-mm attachment gain, and a 3.38-mm defect fill. Nevins et al.[19] examined the healing of intrabony defects treated with bioactive glass ceramic. 2.7 mm of PD reduction and 2.2 mm of clinical attachment gain was noted 6 months after therapy.

The effectiveness of bioactive glass on periodontal intra-bony defects healing was examined by Park et al.[20] 21 intrabony defects received bioactive glass whereas 17 control defects were treated with a flap procedure only. Six months 4.1 mm reduction in PD and 3.0 mm gain in CAL and 2.8 mm defect fill was observed in the test group.

On comparison with the previously published studies utilizing bioactive glass in the treatment of intrabony defects present investigation showed 4.08 mm reduction in PD, 3.25 mm gain in RCAL and 1.33-mm bone fill at the end of 6 months. Results of the present investigation were based on clinical and radiographic examinations only; therefore, it was not possible to assess the type of healing. Good PD reduction and attachment level gain with minimal radiographic hard tissue fill suggest that healing has primarily occurred through a combination of long junctional epithelium and connective tissue attachment. Sequelae of the flap reflection, the apical shift in the gingival margin was observed during the first 3 months of postoperative healing.

Teeth exhibiting abnormal pulpal response due to primary or secondary pulp pathology were subjected to root canal therapy first before surgical intervention [Figure 9].

Figure 9

Baseline periapical radiograph. 46 received endodontic treatment before surgery because pocket was close to the apex and tooth responded abnormally to pulp testing. Tooth exhibited grade I mobility (test site)

Prognosis of teeth showing primary periodontal and secondary pulpal involvement depends primarily on the outcome of periodontal therapy. Periradicular destruction in such cases is because of attachment loss due to the apical extension of plaque. Therefore, after endodontic therapy periodontal surgical intervention should be carried out early. In the present case, periodontal surgical debridement was performed immediately after pulpectomy. In the management of endo-perio lesions, literature is controversial about the effects of endodontic treatment on periodontal tissue healing. Studies have shown no detrimental[21] effects of root canal filled teeth on periodontal tissue healing to impaired[22] periodontal tissue healing. Furthermore, good healing, reduction in tooth mobility, and bone fill (although less) in our case demonstrated no deleterious effect of root canal filling. Another reason for performing pulpectomy was a close approximation of periodontal lesion to root apex. Open debridement near root apex in such cases usually result in the severing of apical neurovasculature and development of severe postoperative sensitivity and pulpal death.

Whereas periradicular lesions due to the primary involvement of pulp require a waiting period of 2–3 months[23] before surgical debridement to allow the endodontic component to heal.

Different ways have been used to improve healing of periodontal osseous defects utilizing various bone grafts, barrier membranes, growth factors, antimicrobial agents, and lasers alone and in combination. Lasers enhance healing and promote increased bone formation through high decontamination and detoxification. In addition, simultaneously exerted low-level laser effect might modulate cell metabolism and stimulate gingival and PDL cell proliferation.[24] Mombelli et al.[25] reported that it is difficult to completely eradicate P. g, Aggregatibacter actinomycetemcomitans (A. a.), and Prevotella intermedia after mechanical therapy (nonsurgical and surgical) and their persistence is associated with poor healing of periodontal pockets. Due to small, flexible tip size laser irradiation can efficiently kill bacteria residing in deep, tortuous pockets, and in the furcation areas. Real-time polymerase chain reaction analysis was utilized by the Gojkov-Vukelic et al.[26] to evaluate the bactericidal ability of the diode laser and the study showed a high reduction in the number of P. g, A. a. immediately after lasing which further reduced at 3 months.

Lack of the positive effects of diode laser on intrabony defect healing is difficult to determine because of variation in different parameters (wavelength and watt) used in studies. Lasing has been performed at different laser wavelengths (810 nm to 980 nm). There is no particular wavelength that is effective in killing pathogens. Recent in vitro study[27] reported that diode laser at 810-nm wavelength is ineffective in killing periopathogens. We did not investigate for the microbiological parameters at different time intervals. It is possible that early recolonization of the treated sites from the adjacent non lased sites may have interfered with healing. The bactericidal ability of diode laser also depends on the therapeutic index which is the ratio of laser fluence that destroys bacteria and laser fluence that is damaging to tissues. Lasers with higher therapeutic index deliver therapeutic dose (well below toxic dose) effective in killing pathogens. Harris and Yessik[28] reported that 810-nm diode laser is less effective in killing P. g because of the low therapeutic index.

Systematic reviews and meta analysis have reported no added benefits of lasers in augmenting the healing of attachment apparatus. In a systematic review and meta-analysis by Behdin et al.[29] it was felt that lasers were not effective in promoting healing toward regeneration compared to conventional approaches. In a recent systematic review small (<1 mm) additional gains were reported for erbium and diode lasers when used in the surgical and nonsurgical treatment of CP, respectively.[30] Cobb[31] reported in a systematic review that lasers lack the ability to sterilize a periodontal pocket. Since diode laser wavelength is highly absorbed by pigmented tissue and has high selectivity to chromophores, it is wrongly believed that it is effective in killing dark pigment producing periopathogens. The truth is that such bacteria do not produce dark pigments while inhabiting periodontal pocket.

Controversies are still prevailing regarding lasers effect on periodontal tissue healing because of utilization of different parameters for delivery of laser beam and different laser systems used.

A small sample size of the present study does not allow definitive conclusions to be made regarding the effects of laser pocket debridement on the regenerative healing. At the selected clinical parameters additional use of diode laser did not enhance the healing of intrabony defects. Additional studies utilizing different laser systems and laser parameters with more number of patients are required to further clarify the potential of lasers in enhancing the regenerative healing.

CONCLUSIONS

Additional pocket detoxification with diode laser did not show superior healing than that achieved with implantation of bioactive glass in the treatment of periodontal intrabony defects.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.