Comparison of Oral Mucosal Biopsies Done Using Scalpel and Diode Lasers: A Vivo Study.

Background: As dental lasers are becoming more popular in the branch of oral medicine for its various advantages and applications, this study was carried out to evaluate better mode of obtaining oral biopsies which is a common and inevitable procedure for providing final diagnosis in majority of conditions. Methodology: In this study, a total of 60 patients who required biopsy for final diagnosis of oral mucosal lesions as part of diagnosis in department of Oral Medicine were selected, out of which 30 were subjected to scalpel biopsies and 30 patients were subjected to diode laser biopsies. A 980 nm Zolar plus diode laser was used for the study. Out of 30 patients who were subjected to laser biopsies, 3W continuous mode settings were used for 15 patients and 3W pulsed mode was used for 15 patients. The specimens were sent to Department of Oral Pathology for histopathological evaluation to provide the final diagnosis. The time taken for each patient, volume of local anesthesia, during operative, postoperative pain scale, and co-relation of provisional and final diagnosis was noted for comparison purpose and the pathologist comments, peripheral tissue damage and artifact's for each slide were noted.
Results: The study results showed the postoperative pain was comparatively less in diodlaser than scalpel, the lasers were patient friendly as the heammorage was negligible when compared to scalpel and suturing was not required. The pulsed mode in diode laser was advantageous over continuous mode when amount of thermal damage and postoperative pain score was compared.
Conclusion: The results showed that oral biopsies can be made better using diode lasers, by having thorough knowledge on the device. Copyright:

INTRODUCTION

A biopsy is when a portion or all of a lesion is removed to allow for histological analysis and a definitive diagnosis. The word, “biopsy” has been derived from the Greek words, “Bios” (life) and “Opsis” (vision): vision of life. Biopsy is the gold standard diagnostic method for obtaining sufficient representative tissue for histological assessment and ultimate diagnosis.[1] The application of biopsy in the management of oral lesions includes a sequence of steps: adequate data collection, competent diagnostic skills, evaluation and representation of the pathologist's report, proper surgical management, and comprehensive patient follow-up.[2]

A biopsy may be either incisional or excisional. An incisional biopsy is one to extract one or more abnormal samples so that suitable therapy can be begun following histological assessment. By contrast, an excisional biopsy involves complete removal of the lesion, so it is a diagnostic and therapeutic procedure.

During a biopsy procedure, it is important that the lesion's margins be accessible so that any marginal infiltrations or any benign to malignant transformation of the lesion can be examined histologically.[3]

The aim of the biopsy is to:

Define a lesion on the basis of its histopathological aspect

Contribute to the assessment of the efficacy of the treatment

Facilitate the prescription of specific treatment

To establish a prognosis of neoplastic, premalignant, and nonneoplastic

Act as a document with medical-legal value.

Scalpel, electrosurgical, and laser are the three most frequent methods for cutting oral soft tissues in dentistry. Each of these methods has their own advantages and disadvantages and are different from the standpoints of hemostasis, healing time, cost of instruments, width of the cut, anesthetic required, and disagreeable characteristics, such as smoke production, the odour of burning flesh. Scalpel and laser systems are widely utilized as effective tools in soft tissue surgical procedures.

Conventionally, lasers have been widely used in dentistry for root canal disinfection, coagulation and haemostasis, exposure of implants, root planing, gingival and periodontal surgeries, biopsies, excision of oral lesions, temporomandibular disorders, and preprosthetic surgery.

Lasers for soft-tissue cutting have certain disadvantages which include: because of the possible threat of laser light, laser use necessitates a learning period and rigorous safeguards; laser can cause eye damage, thus protective glasses are required during use; there is a burning flesh odor; some techniques are time consuming; and there is reported tissue damage.

The fear of the pain from incision by scalpel in spite of anesthesia in location is always a nightmare for the patient. In comparison with conventional scalpel, laser has many benefits, such as ease of soft tissue ablation, hemostasis,[4] instant sterilization, reduced bacteremia, wound contraction, reduced edema of the surgical site, less anesthesia, minimal scar, reduced mechanical trauma, less operative and postoperative pain,[56] increased patients' acceptance,[7] no or few sutures, reduce patients' fear and pointed and angulated beam helps in posterior areas were scalpel is difficult to use.

This study is done to evaluate the safety and efficacy of diode laser to scalpel in oral mucosal biopsies which are patients and surgeons friendly when compared to scalpel. This study is aimed to compare, evaluate, and establish the efficacy and accuracy of diode lasers and scalpel for oral mucosal biopsies under local anesthesia.

Aim and Objectives

The aim of this study was to evaluate better modes of obtaining oral biopsies done with diode laser and scalpel, to assess the intra and postoperative observations in patients when subjected to scalpel and diode laser biopsies, assessment of peripheral tissue damage microscopically and pathologist comments on specimens done using scalpel and diode laser, assessment of efficacy and tissue damage in specimens done using diode laser in continuous mode and pulsed mode and comparison of scalpel versus pulsed mode versus continuous mode to attain the better modality.

METHODOLOGY

A total of 60 patients, provisionally diagnosed with oral mucosal lesions and required biopsy for final diagnosis were subjected for the study. Thirty biopsies were done using scalpel. 15 biopsies were done using diode laser in continuous mode and 15 biopsies were done in pulsed mode with the same power settings of 3w. Both incisional and excisional biopsies were done based on the clinical diagnosis. Before the procedure was undertaken, the characteristics of the lesion (size, shape, color, texture, consistency, and time of evolution, associated signs and symptoms, regional nodes) were described in the patient's clinical records together with a presumed diagnosis and possible differential diagnosis. Informed consent of patient was taken.

Local infiltration of lignocaine was given, the quantity of effective local anesthesia given (ml) and time taken for procedure was noted for all the patients. Postoperative medication was prescribed for all the patients and was asked to use only if pain/swelling/discomfort was present. The tissue taken was large enough so that it included normal and suspicious tissue. The specimen was stored in 10% formalin solution and sent for histopathological assessment [Figure 1].

Figure 1

Preoperative laser biopsy

The tissue damage, artifacts, and pathologist difficulties in diagnosing the lesion, quality of slides at the periphery and center were graded (1-good, 2-average, 3-poor, 5-non diagnostic) microscopically and width of necrotic border in laser cut tissues were measured using Quick capture pro 6.0 version software and comparison of continuous mode and pulsed mode laser biopsies for the same was also done [Figure 2]. The quantity (ml) of local anesthesia used for laser and scalpel biopsies is compared [Figure 3]. Recall of the patients is done; intraoperative and postoperative pain is measured using pain analog scale. All patients who require biopsy for the final diagnosis of oral mucosal lesions as part of diagnosis in department were included in the study and patients who were immunocompromised [Figure 4], pregnant, and diagnosed provisionally for a vascular disorder were excluded [Figure 5].

Figure 2

Postoperative laser biopsy

Figure 3

Hyalinization

Figure 4

Detachment of keratin

Figure 5

Carbonization

RESULTS

All measurements were entered and analyzed using SPSS software. A Chi-square test and t-test are used to compare the efficacy, reliability, and accuracy of diode lasers with scalpel in obtaining oral biopsies. Differences were considered as statistically significant when P values were <0.05.

The volume of L. A in ml used to complete the procedure for every patient was noted and compared statistically. The results were statistically significant with P = 0.000. The volume of L. A required for scalpel was more than compared to laser group. Among the laser group, the pulsed mode and continuous mode were compared and the results were statistically significant with P = 0.002. The continuous mode group required greater volume of LA than pulsed mode group [Graph 1].

Graph 1

Comparison of postoperative vas score between laser and scalpel

The intraoperative pain scale was measured using visual analog scale (VAS) score and all the patients in both the groups gave score 0 pain. Intraoperative bleeding assessment showed more bleeding in scalpel group than laser group and among laser group, pulsed mode had mild bleeding and continuous mode had absolutely clear surgical field [Graph 2].

Graph 2

Comparison of postoperative vas score between continuous mode and pulsed mode

The time taken to complete the procedure for each patient was noted in minutes and compared. The average time taken for scalpel biopsies is 13.07 ± 3.16 min whereas time taken for laser biopsies is 18.33 ± 4.69 min and the values are statistically significant with P = 0.000 which shows lasers are time consuming than scalpel. Among the laser group the continuous mode biopsies required an average time of 15.467 ± 4.549 min and for pulsed mode biopsies required 22.000 ± 3.927 min and the results were statistically significant with a P = 0.000 which showed pulsed mode required more time than continuous mode. The postoperative pain scale between laser and scalpel group, results were statistically significant with P = 0.003. The scalpel group had more pain when compared to the laser group and among the laser group values were statistically significant with P = 0.004, which shows pulsed mode group had lesser postoperative pain than continuous mode [Graph 3]. The quality of the slide at the center and periphery was assessed histologically based on the artifacts by pathologist as good, fair, poor, and nondiagnosable [Graph 4].

Graph 3

Comparison of volume of L.A used between laser and scalpel

Graph 4

Comparison of volume of L.A used between continuous mode and pulsed mode

The peripheral and center quality of the slide was good for scalpel when compared with the laser samples. Moreover, among the laser group, the results showed that the pulsed mode had better quality at the periphery and center than continuous mode [Graph 5]. The common artifacts seen among the laser biopsies as enlisted by histopathologist in the current study are tissue necrosis, fibrous degeneration, hyperchromatism, nuclear elongation, intercellular spacing, loss of cellular morphology, intercellular edema, hyalinization, shedding of keratin, vacuolation, and epithelium separation from connective tissue [Graph 6]. The thermal damage produced by laser was assessed by measuring the width of necrotic border using quick capture software. The mean width of necrosis at the periphery was 279.84 μm for continuous mode and 208.766μm for pulsed mode which shows that pulsed mode had a lesser thermal damage than continuous mode.

Graph 5

Comparison of quality of slide at the periphery between scalpel and laser

Graph 6

Comparison of quality of slide at the center between scalpel and laser group

DISCUSSION

A biopsy is a surgical procedure used to determine a definitive diagnosis of a lesion and to create an effective treatment strategy. A biopsy may be either incisional or excisional.[3] Oral biopsies can now be performed using a variety of equipment, the most common of which is the scalpel, though lasers have recently been attempted for some advantages over scalpels. The scalpel enables for the extraction of a tissue piece with well-defined peri-incisional margins and minimal structural changes. However, this surgery always requires anesthesia and sutures, and the operative field is not bloodless.[8]

Assessment of pain during the procedure was taken as “intraoperative VAS.” Intraoperative VAS score was 0 for both laser and scalpel groups. Yet some patients in the scalpel group complained a sense of pricking during suturing. Discomfort is less in laser as compared to conventional surgical procedures[1] as mentioned by Esmaeil et al.[9] In a study by Rishikesh et al. in 2010, similar results were mentioned when laser and scalpel excision were compared, placement of sutures and patient discomfort was seen in scalpel group.[3]

Although the mechanism of analgesic effects of laser therapy is not well understood, an increased pain threshold through the alteration of neuronal stimulation and firing pattern and the inhibition of the medullary reflexes is thought to be involved.[10] Blockage of nerve endings by the charring effect of the laser might reduce the pain, and also the provision of a sterile environment proves to be of immense benefit to the patient.[11] The thin denaturalized collagen layer formed on the surface of surgical wounds after laser surgery serves to isolate the surgical wound from irritation by oral fluids further reducing the pain.[12] The reduced postoperative pain can also be attributed to the fact that the cellular disintegration caused at the impact site does not allow for the release of inflammatory mediators.[13]

In a study Kalakonda et al.[14] comparing laser and scalpel surgeries, pain observed at the laser-treated site after 24 h was almost nil to slight compared to moderate pain at the scalpel treated segment as noted on VAS scale, which is in accordance with our study. Similar study done by Ize-Iyamu et al.[15] on laser-assisted frenectomies, he concluded that the surgeries were accomplished with minimal anesthesia, minimal discomfort, no suture, no antibiotics, no post-operative visits, and great patient satisfaction. In a study conducted by Borcher[16] comparing the continuous mode and pulsed mode, he also concluded that pulsed mode group had lesser pain than continuous mode, which is in accordance with our study. This might be because of lesser thermal damage to the surrounding tissues in pulsed mode.

An observatory comparison of bleeding at the surgical field intraoperatively was done among the two groups. Bleeding was observed more in scalpel group than in laser group and among laser group, pulsed mode had mild bleeding and continuous mode had clear surgical field. Laser wounds can seal blood vessels up to 500 μm in diameter. Normal lateral thermal damage results in contraction of collagen that is contained within vascular walls and is manifested by constriction of vascular lumen, resulting in sealing of blood vessels up to 500 micro meter in diameter. When the tissue is incidentally heated by laser beam to temperatures over 600C, it undergoes coagulation and this coagulation phenomenon is the basis of most surgical applications of laser.[17] Alteration in the molecular structures of tissue collagen from trihelical to randomly disturbed helical polymers and coils after laser beam radiation is the basic physical event which will lead to shrinkage of the collagen fibers after photocoagulation, the lased tissue constricts against the proximal vasculature and the vessels shrink as a result of the collagen in their walls which result in enhanced hemostasis. Laser damage to erythrocytes attracts a population of platelets which encourage intraluminal thrombosis, further decrease in the blood loss and this explains why the laser wound group had minimal blood loss in comparison to the scalpel wound group.[18]

In a study by Ize-iyamu et al.,[15] comparing scalpel and diode laser concluded that scalpel surgery caused bleeding during the operation and there was no bleeding in the laser-treated wound. Apollonia et al. used diode laser in intraoral surgeries. In his study, he observed no hemorrhage in cases treated with diode laser and suturing was not required after the surgery.[19] The use of diode laser in Oral Maxillo Facial Surgery (OMFS) procedures gives excellent coagulation even though oral environment is highly vascular.[21] Sarver and Yanosky compared laser with conventional blade surgery, laser excision seemed more convenient in view of lack of bleeding and no sutures required.[20] According to Pirnat[22] using near infrared lasers on soft tissue, there is no bleeding due to a combination of sealing of small vessels through tissue protein denaturation and stimulation of factor VII production in clotting. In a study by Borcher,[16] he stated that there was very minimal bleeding in patients operated with continuous mode when compared to pulsed mode. This is maybe because of the blood vessels were sealed better by the influence of the larger amount of thermal energy delivered by the continuous mode of operation than pulsed mode as seen in the current study.[23]

Procedure time (P.T) is the time taken for completion of the biopsy procedure that is from the starting time to the end time. The first incision with scalpel and the first contact with laser was taken as the starting time. Completion of the procedure, which includes suturing for the scalpel group, is taken as the end time.

According to Panagiotis et al., the disadvantage of diode laser is the time required for excision in comparison to blade.[24] The cutting efficiency of scalpel was quicker than laser but some additional time was required for suturing. In a study by Jose et al., the results were contradictory as it was found the total treatment time with laser to be less in comparison to scalpel which was attributed to increased intraoperative bleeding and also suturing at the end.[25]

The total volume of local anesthesia used for each patient was noted. For every patient, first 0.5 ml of L. A was given and then checked for pain perception with a prick by scalpel for scalpel group and the surgical site was lazed using the laser for laser group and if the patient had pain, then another 0.5ml was administered and pain perception was checked. This procedure was repeated till the patient was painless during the procedure. The volume of L. A required for the patient to have no pain during the procedure was noted as the volume required for the procedure.

The extraordinary rapid cell vaporization with loss of intracellular fluid, chemical mediators (cytokines), and denaturation of intracellular substance and protein is posited to result in a markedly less intense local inflammatory response and consequently less local pain, edema, and cicatrix formation[26] and this may explain the need for small amount of local anesthesia required to perform laser surgery in comparison to the scalpel incision. In a study by Shalawe et al.,[26] he stated that volume of local anesthesia used for scalpel is more than laser and in a study by Kalakonda et al.[14] in which he compared diode laser and scalpel techniques for vestibuloplasty procedure, he concluded that scalpel procedure required bilateral mental nerve block whereas laser-assisted vestibular deepening was performed with minimal amount of local infiltration anesthesia, which are in accordance to the current study.

Histologically, the quality of slide at the periphery and center was assessed by oral pathologist. The quality of slide was graded as good, fair, poor, and nondiagnosable based on the alteration of cellular morphology due to the thermal effect by laser, procedural, and tissue handling errors.

The amount of energy that is absorbed by the tissue depends on the tissue characteristics, such as pigmentation and water content, and on the laser wavelength and emission mode. Tissue compounds called chromophores preferentially absorb certain wavelengths. Hemoglobin, the molecule that transports oxygen to tissue, reflects red wavelengths, imparting color to arterial blood. It, therefore, is strongly absorbed by blue and green wavelengths. Venous blood, containing less oxygen, absorbs more red light and appears darker. The pigment melanin, which imparts color to skin, is strongly absorbed by short wavelengths. Water, the universally present molecule, has varying degrees of absorption by different wavelengths, the above explanation can be attributed to varying quality of slides among laser group though same power settings of 3w in continuous mode or pulsed mode were used.[27]

The common artifacts seen among the laser biopsies as enlisted by oral pathologist in the current study are tissue necrosis, fibrous degeneration, hyperchromatism, nuclear elongation, intercellular spacing, loss of cellular morphology, intercellular edema, hyalinization, shedding of keratin, vacuolation, and epithelium separation from connective tissue. The artifacts encountered were similar to that mentioned by Pogrel et al.[28] in his study. Cercadillo-Ibarguren et al.[29] based on their study said that the thermal effect of laser does not undermine the histological diagnosis of a lesion since the remaining tissue attached outside of the irradiation margin is not damaged and can be properly diagnosed. Janda et al. compared histological effects of Ho:YAG, Nd:YAG, and two diode lasers with wavelengths of 830 and 940 nm. Low thermal effects were found in depth of tissue with Nd:YAG and diode lasers as large carbonization zones at the surface resulted in high power loss. Capodiferro et al. noted that regressive tissue changes due to thermal cut of diode lasers are usually negligible, thus allowing adequate histological examination and correct diagnosis. Suter et al.[30] evaluated histopathological characteristics and suitability of diode and CO lasers for performing excisional biopsies of oral mucosal lesions and concluded that both the lasers can be used successfully. Diode laser is, however, comparatively cost effective and easy to operate.[31]

CONCLUSION

Following conclusions are drawn from the present study:

The use of laser to perform oral biopsy has several advantages over the scalpel, like

Increased patient acceptance as there was very minimal postoperative pain.

The volume of anesthesia required for procedure is significantly less.

Better hemostasis.

No suturing was required.

The advantage of scalpel over laser is that

The cutting efficiency of scalpel is quicker, so overall P.T was less for scalpel

The quality of histopathological slide at the periphery and center is better, as there was no thermal damage in scalpel.

Among the laser group the patients operated on pulsed mode had lesser postoperative pain, amount of L. A required was lesser, the quality of slide at center and was better and width of necrotic border is lesser than continuous mode, were as the procedural time and bleeding was lesser in continuous mode.

To conclude laser is definitively an adjunct to conventional scalpel in obtaining oral biopsies even though there were artifacts, they were negligible, thus allowing adequate histological examination and correct diagnosis and among laser pulsed mode is better due to its lesser width of thermal damage and better quality of histopathological slide.

A minimum of 5 mm of normal tissue margin to be included if a diode laser with a power setting of 3W or lesser is used while taking a laser biopsy as thermal damage at the margins may pose problems in determining the extent of lesion as well as diagnosis of neoplastic or dysplastic lesions.

Care should be taken to reduce the thermal damage, for which proper knowledge and training is a must for a clinician to use a laser at his practice as, ”you wouldn't go hunting rabbits with an elephant gun,” that is proper power settings should be selected based on the nature of the tissue operated and laser used and other measures like using the laser in pulsed mode, air suction and water coolants have to be taken to further reduce the thermal damage.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.