Efficiency of Laser versus Bur in Impacted Mandibular Third Molar Surgery: An Original Research.

INTRODUCTION: In oral and maxillofacial surgery, their clinical application has largely been restricted to soft tissue. Hence, the aim of this study was to assess the feasibility of erbium-yttrium aluminum garnet (Er: YAG) laser in bone cutting for removal of impacted lower third molar teeth and to compare its outcomes with that of surgical bur.
MATERIALS AND METHODS: The study comprised forty subjects requiring removal of impacted mandibular third molar, randomly categorized into two equal groups of 20 each, who had their impacted third molar removed either using Er: YAG laser or surgical bur as per their group, using standard methodology of extraction of impacted teeth. Clinical parameters such as pain, bleeding, time taken for bone cutting, postoperative swelling, trismus, wound healing, and complications were compared for both groups.
RESULTS: Clinical parameters such as pain, bleeding, and swelling were lower in laser group than bur group, although the difference was statistically not significant. However, postoperative swelling showed a significant difference in the two groups. Laser group required almost double the time taken for bone cutting with bur. Trismus persisted for a longer period in laser group. Wound healing and complications were assessed clinically and there was no significant difference in both the groups.
CONCLUSION: Based on the results of our study, the possibility of bone cutting using lasers is pursued, the osteotomy is easily performed, and the technique is better suited to minimally invasive surgical procedures. The use of Er: YAG laser may be considered an alternative tool to surgical bur, especially in anxious patients. Copyright:

INTRODUCTION

During the past two decades, lasers have been widely used in many medical specialties including general surgery, ophthalmology, and dermatology. In oral and maxillofacial surgery, their clinical application has largely been restricted to soft tissue. Initially, ruby and long pulse CO2 laser were used for cutting mineralized tissues, but results revealed serious biological complications, thermal damage,[12] severe carbonization effects, and delayed bone healing. Later, comprehensive advancements of short-pulsed infrared laser systems paved the way for successful ablation of dental hard substances and bone. Erbium-yttrium aluminum garnet (Er: YAG) lasers are solid lasers (Er: Y3Al5O12), which typically emit light with a wavelength of 2940 nm, which is infrared light. Due to its wavelength of 2.94 mm, which matches exactly the absorption peak of water[3] and is also absorbed by hydroxyapatite, erbium laser radiation is very efficient in cutting hard structure like bone, to a superficial layer of a few micrometers.[4] Our study was to assess the feasibility of Er: YAG laser in bone cutting for the removal of impacted lower third molar teeth and compare its outcomes with that of surgical bur.

MATERIALS AND METHODS

This prospective study was conducted in forty healthy male and female participants with impacted mandibular third molar, who visited the outpatient department of oral and maxillofacial surgery for the removal of impacted mandibular third molar. Patients on anticoagulants, immunosuppression, systemic or local bone diseases, radiotherapy, pregnant, and lactating mothers were excluded from the study. Treatment plan and possible complications were explained to all participants and informed consent was obtained. Detailed history was recorded in a standardized format. All were thoroughly examined clinically, and routine hematological investigations were done. Preoperative radiographic evaluation of the area was done on intraoral periapical radiographs and orthopantomogram and type of impaction (mesioangular, distoangular, and horizontal) was recorded. They were randomly categorized into two equal groups of twenty each (Group A: BUR, Group B: LASER), who had their impacted third molar removed either using bur or Er: YAG laser as per their group, using standard methodology of extraction of impacted teeth. The procedure was carried out under local anesthesia. Ward's incision was made and mucoperiosteal flap reflected protecting the lingual nerve. In Group A, bone was removed on buccal and distal portion as required with surgical round bur (#6) using copious irrigation with normal saline. In Group B, Er: YAG laser was used to cut bone and if necessary, the tooth. The surgeon wore protective glasses during the procedure. The wavelength of the Er: YAG laser was 2.94 mm, the pulse energy was 700 mJ (0.7 W), at 10 pulses/s or 10 Hz. The duration of each pulse was about 250 s. The laser tip was kept 1 to 2 mm away from the bone or tooth. The area was copiously irrigated with sterile water. Tooth was delivered with elevator taking care of curvature of roots. Any sharp bony margins were smoothened with bone file. The socket was then inspected, irrigated with normal saline, and wound was closed with 3.0 silk suture. Clinical parameters such as pain (recorded on visual analog scale as mild for 1–4, moderate for 5–7, and severe for 8–10), bleeding during tooth removal, time taken for bone cutting, postoperative swelling, trismus, wound healing, and complications were recorded for both the groups. Bleeding was recorded as severe if blood was pumping from the wound and did not stop or slow down with pressure, moderate if it slowed or stopped with pressure but started again upon removal of pressure, and mild if stopped on its own or with 15 min of pressure.[5]

Objective assessment of postoperative swelling was done by measuring the linear distance between corner of mouth and the center of tragus of ear and angle of mandible (gonion), and lateral canthus of eye was measured pre and postoperatively to quantify facial swelling[56] which excluded lingual swelling. Trismus was recorded as painless mouth opening measured between inter incisal distance. Healing was recorded as interrupted/smooth (presence or absence of persistent postoperative pain and swelling, change in color of mucosa, pus discharge, and palpable lymph nodes). Complications noted were infection (including dry socket), altered sensation paresthesia/anesthesia/hyperesthesia of inferior dental, and lingual nerve.

RESULTS

Mean age was 27.2 in bur group and 27.7 in laser group. Bur group had 11 females (55%) and nine males (45%) and laser group had eight females (40%) and 12 males (60%). Among all patients, 85% had mesioangular, 5% horizontal, and 10% distoangular type of impaction. Statistical analysis of variable outcomes revealed no statistically significant difference in pain and bleeding, but there was statistically significant difference in swelling in both groups [Table 1]. Time taken in bone cutting was significantly more in the laser group, with almost double time taken for bone cutting compared to bur. Trismus persisted for longer period in laser group. In our study, wound healing was assessed clinically, and a result showed no significant difference in wound healing between the two groups, although 10% of cases in bur group and 5% of cases in laser group showed dry socket [Table 2]. Five percent cases in bur group showed temporary paresthesia. Although the follow-up period was too short to allow any long-term assessment on quality of healing, short-term follow-up showed no differences in healing between the groups [Table 3].

Table 1

Comparison of the various presentations between the groups.

Clinical feature	Laser’s group	Bur’s group	P
Pain
Mild	89%	80%	NS
Moderate	10%	5%
Severe	1%	0%
Bleeding
Mild	100%	92%	NS
moderate	0%	8%
Intraoperative time in bone cutting	27 min	16 min	0.000
Time for wound healing	5 days	7 days	NS

Table 2

The comparison of swelling between the groups

SWELLING	BUR			LASER
	MEAN	SE.MEAN	SIG	MEAN	SE.MEAN	SIG
A pre-op a 3 DAYS	12.20	0.271	0.00	12.20	0.281	0.00
	14.10	0.234	13.71	0.264
A pre-op a 1 WEEK	12.31	0.271	0.00	12.20	0.281	0.0320
	12.95	0.254	13.87	0.276
A pre-op a 15 DAYS	10.325	0.271	0.152	12.20	0.281	0.320
	12.30	0.244	13.71	0.264
B pre-op b 3 DAYS	10.311	0.1787	0.00	10.111	0.2039	0.18
	11.14	0.168	10.49	0.211
B pre-op b 1 WEEK	10.311	0.1787	0.018	10.111	0.2039	0.576
	10.64	0.136	10.24	0.195
B pre-op b 15 DAYS	12.21	0.1787	0.320	10.11	0.2039	0.187
	10.311	0.1761		9.89	0.1698

A, one fourth the distance from the center of tragus of ear & corner of mouth. B, one fourth lateral canthus & angle of mandible (gonion). SE.- standard error

Table 3

The comparison of trismus between the groups.

Mouth opening	Group	Mean	SE.mean	P
Preoperative	BUR Group	31.70	0.584	0.855
	Laser Group	31.85	0.632
One day	BUR Group	22.45	0.874	0.0000
	Laser Group	18.20	0.474
2 days	BUR Group	28.30	0.472	0.0000
	Laser Group	23.95	0.565
3 days	BUR Group	30.50	0.417	0.0000
	Laser Group	26.40	0.586
7 days	BUR Group	33.45	0.520	0.0000
	Laser Group	30.85	0.439
2 weeks	BUR Group	34.90	0.327	0.0361
	Laser Group	32.50	0.525

Inter-incisal distance between the groups in millimeters. SE.- standard error

DISCUSSION

Osteotomies are necessary in oral and maxillofacial region for dentoalveolar surgery, impacted tooth removal, traumatology, surgery for dentofacial deformities, and reconstruction. Mechanical drills and saws have been used efficiently to cut bone for hundreds of years. Despite improvements in technology, metallic cutting instruments result in deposition of debris on bone, heating,[7] vibrations,[8] noise, and discomfort. Recently, lasers have been in demand for obvious advantages such as sterilization of the surgical site while cutting tissue, simultaneous hemostasis of small vessels, resulting in decreased bleeding and a dry surgical field, no-touch technique, reduced postoperative pain, less edema, and limited scarring.[9] Pain is one of the most important features after surgical extraction of impacted tooth. Our study showed reduced intraoperative as well as postoperative pain in laser-treated patients. We observed mild pain in 100% of patients in laser group, but in bur group, 85% had mild, 15% moderate, and 5% severe pain. However, statistical analysis showed no significant differences. Similar findings have also been reported by Taguchi[10] and Abu-Serriah et al.[11] Possible mechanisms of pain reduction in Er: YAG ablation are the disruption of nerve terminals in bone, combined with a degeneration of nerve ending. Second, vibration speed caused by bur is 100 times higher than laser. This higher frequency has its spectrum near the peak sensitivity of hearing, as a potential factor of discomfort and pain provocation. The Er: YAG laser produced no smoke during the ablation process. There was also no friction sound or vibration; the apparatus does produce a repetitive snapping sound, which represents the explosive interaction with chromophores. This has been measured in one study at between 99 and 121 dB although patients did not find this unpleasant, and studies have shown that this sound does not damage hearing.[12] Er: YAG laser has a high bactericidal potential even at low energy densities.[1314] Gonzalez et al.[2] compared the in vitro bone and cartilage-ablation characteristics of the solid-state Er: YAG laser to those of the carbon dioxide laser and observed that Er: YAG ablated bone averaged 5 μof adjacent tissue thermal injury, compared with 67 μ with carbon dioxide-ablated bone. Ablated cartilage averaged 2 μ of adjacent tissue thermal injury with Er: YAG laser, compared with 21 μ with the carbon dioxide-ablated cartilage. Hemostasis is one of the inherent properties of low-intensity lasers. Infrared laser can change the functional activity of proteins and its effect is directly proportional to dose and frequency of radiation impulses. Bleeding in our study showed 90% of patients in laser group had mild bleeding and 10% moderate, whereas in bur group 80% had mild and 20% moderate bleeding. There was less bleeding in laser group than bur group which provides better visibility of operating field and hence better outcome. Although statistical analysis showed no significant difference in bleeding between both the groups, our study correlates with the studies of Stu¨ binger.[15] There was statistically significant difference in bone cutting time of both groups as P value was 0.004 (<0.005).

Average time observed in bur group was 11.9 min and in laser group was 23 min. Laser group had almost double time taken for bone cutting compared to bur. This was particularly true when the laser was used to cut thick or dense bone or tooth. Bone contains mineral salts, which retard vaporization, resulting in prolonged duration of operation. Considering the time taken during cutting, the patient should be explained about the procedure before surgery.[1617] Papadaki et al.[18] studied vertical ramus osteotomy feasibility with all energy settings and observed that the time required for ostectomy decreased considerably from 28 to 5.33 min as the energy per pulse increased. He suggested that 2000 mJ/pulse was the most efficient setting in terms of time.

Trismus was greater in the laser group and persisted for longer duration of time. The difference was significant during the first postoperative week. A greater reduction in the range of mouth opening was found after laser than after bur treatment.[11] Generally, the severity of the intervention, massiveness of tissue, and bone destruction leads to trismus.[18] Longer period manipulation of the mucoperiosteal flap with a retractor during the impacted third molar surgery contributed to the more severe trismus.

Wound healing in our study was assessed clinically, and results showed no significant difference in wound healing between two groups; although 10% of cases in bur group and 5% of cases in laser group showed dry socket. Furthermore, 5% of cases in bur group showed temporary paresthesia. Although the follow-up period was too short to allow any long-term assessment of the quality of healing, short-term follow-up showed no differences in healing between the groups.

CONCLUSION

In this study, we compared the removal of impacted mandibular third molar using bur and Er: YAG laser for bone cutting. Our study showed that laser allows precise bone ablation without any visible, negative, thermal side effects; offering advantages such as sterilization and bactericidal effect, spontaneous hemostasis, reduced postoperative pain, edema, and limited scarring. Since the laser tip was used in a noncontact mode and could be positioned freely, unrestricted cut geometries were feasible. Adjacent soft-tissue structures could be preserved and were not harmed by the laser beam. The main disadvantages of laser included increased operating time, long-term postoperative trismus, lack of tactile sensitivity, difficult safety measures, and cost factor in laser equipment and maintenance. Furthermore, the ablation process using laser and water spray resulted in a considerable spatter of blood. An additional risk may be the creation of an air embolism in the tissue, due to the air-induced water spray. Based on the results of our study, we conclude that possibility of bone cutting using lasers is pursued. The osteotomy is easily performed and the technique is better suited to minimally invasive surgical procedures. The use of Er: YAG laser may be considered an alternative tool to surgical bur, especially in anxious patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.