Healing Assessment of Oral Mucosal Wounds Using Erbium , Chromium : Yttrium-Scandium-Gallium-Garnet Laser Versus Scalpel Blades

Aims : The study aims to compare wound healing histologically and serologically by using two different surgical procedures and to evaluate the efficiency of the Er,Cr:YSGG laser on wound healing after surgical procedures. Materials and Methods : Sixteen New Zealand rabbits were used as experimental animals. The animals were divided into two groups: group I and group II, each group consisted of 8 rabbits. In group I; stainless steel scalpel blade NO.15 was used for making the incision, in group II Er, Cr: YSGG laser was used for making the incision. Two rabbits were sacrificed from each group at the 1st ,3rd ,7th and 14th days after procedures. On the day of sacrificial blood was collected from each rabbit for serum and serological analysis to determine serum level of TNF-α. Results : 1:Histological findings of this study revealed that there was a significant difference in inflammatory cells infiltration at 1st day between the two groups, while there was no significant difference at 3rd , 7th and 14th day periods. Granulation tissue formation appeared higher in erbium group, while scalpel blade incision showed less amount of granulation tissue formation. In reepithelialization at 1st day all section shows nil score in both groups, at 3rd day re-epithelization appeared significant difference, and no significance difference at 7th and 14th days between erbium and scalpel blade. 2: Serological findings of this study shows that TNF-α level in serum have no significant differences between two groups at different time periods. Conclusions : Εr,Сr:ҮЅGG laser has numerous benefits for use particularly in oral surgery , due to low inflammatory reaction and less ulceration and smallest damage of the oral mucosal tissue, while more inflammatory cell infiltration occurs in comparison with group that used surgical scalpel blade.

Healing Assessment of Oral Mucosal Wounds Using Erbium, Chromium: Yttrium-Scandium-Gallium-Garnet Laser Versus Scalpel Blades

INTRODUCTION
Wound define as breakdown in he normal continuity of he covering skin and/or mucosa; he loss of epithelial barrier, with or without disruption of underlying connective tissue (dermis, fascia and muscles) ,wounds occurred due to external damage (1)(2)(3)(4)(5) . The wound healing process is a complex pathophysiological mechanism that includes a cascade of coordinated inflammatory and proliferative events (6) .
Surgical scalpels are fundamental tools to make soft tissue incisions (7) . The problems of using scalpel blade are pain, bleeding specially in highly vascular lesion and in a patient with bleeding disorders (8) . Many laser systems units are alternative to surgical knife blade on surgeries involving oral soft and hard tissues (9) .
The erbium laser first developed in 1990 and then came to the dental market and get approval from the Food and Drug Administration (FDA)to use on human being in 1997 (10) .The performance of he laser is based on peak absorption rates of each laser wavelength. With erbium laser has an affinity for (H2O) particles , which makes hem able to cut hard tissue as well as soft tissue (11) .
The biomarkers are biological indicator substances, he specific biomarkers can be identified by diagnostic tests, imaging technologies and o her measurement devices of an individual's health status (12) . Researches have shown many mediators and cellular events happened within he wound healing that can be served as biomarkers. Neutrophils, ,Natural Killer Cell ,Macrophages, platelets and fibroblasts release cytokines molecules including Tumor necrosis factor-α (TNF-α) (13) .

MATERIALS AND METHODS
Sixteen healthy male New Zealand rabbits aged between 3 and 4 months and weight between 1.25 and 1.5 kg were used. They were retained in animal house at standard environment, and the animals were kept at a temperature of 30 ± 5 ∘C and all they received same amount of nutrition, so the outcome of wound healing be same in all rabbits .
All experimental procedures operating on rabbits followed the animal care protocol to prevent any health problems and to promote efficiency.

Animal grouping
The animals were randomly assigned into    (-20℃) for assaying the level of TNF-α by ELISA test.

Histological analysis
The tissue was immediately dissected from buccal mucosa and introduced in a solution of 10% Neutral Buffered Formalin. The specimens were harvested, and sections of five microns in series were sliced and stained by hematoxylin and eosin for histological analysis.
The histometric measurements depending on criteria in (Tables 1,2, and 3) were done under a light microscope connected to a digital camera at magnification of x10and x40. 2 Mild : inflammatory cells present iո fewᴡ numbers, less than ½ of the field (X10). 3 Moderate: inflammatory cells could be seen iո more than ½ of the field (X10). 4 Severe or abundant : inflammatory cells present iո huge numbers, more than ¾ of the field (X10).

Table (2):
Criteria for amount granulation tissue formation (Scoring): (24,25) 1 Absent of granulation tissue formation iո wound 2 Quantity of granulation tissue formation iո the wound gap is scanty 3 Amount of granulation tissue formation is moderate iո t tissue. 4 Total amount of granulation tissue formation iո the wound is profound.  (26) 0 Re-epithelization at the edge of the wound. 1 Re-epithelization ո covering less than half of the wound. 2 Re-epithelization covering more than half of the wound. 3 Re-epithelization covering the entire wound, irregular thickness . 4 Re-epithelization covering the entire wound, normal thickness.

Statistical analysis
The current study used non-parametric utest (Mann-Whitney), because its comparative study between two groups and data not followed specific disruption.

RESULTS
All the rabbits survived during experimental procedures.

At Day one after procedure
The scalpel group appeared moderate number of inflammatory cells infiltration present in slides section, see (Figures 2, 3, and          and 7).

Serological test
Cytokines level like TNF-alpha will be much higher in non-healing wound and wound with high inflammatory response due to these cytokines released be inflammatory cells like what Patel, Maheshwari (13) , Shah, Omar (21) found in their researches.
Gohel, Windhaber (22) found in his study, that performed on chronic ulcer to analysis the relationship between level of cytokines like TNF-alpha and wound healing process ,when blood sample is collected from patients suffered of chronic ulcer, found was poor relationship between cytokines and ulcer healing is consequential remains unknown.
El Ayadi, Herndon (23) Observed the appearance of pro-inflammatory cytokines is significantly changed after burn injury, and the concentration of these cytokines alone or with respect to each other can be used to predict septic condition during healing.

CONCLUSIONS
Depending on results and statistical analysis in (Table 6)