Extraction wound healing in (jesaiivated rats
Lipa Bodner\ Dan Dayan^ Doron Rothchild^ and llan Hammel^ Sections of 'Oral and Maxitlotacial Surgery, 'Oral Pathology and Oral Medicine, Maurice and Gabriela Goldschteger School ot Dental Medicine, ^Department ot Pathotogy, Sackter Facutty of Medicine, Tet Aviv University, Israel
Bodner L. Dayan D. Rothchild D. Hammel 1: Extraction wound healing in desalivated rats, .1 Oral Pathol Med 1991; 20: 176-8, Wound licking has been shown to promote extraoral wound healing among animals. Although the oral mucosa is bathed in saliva. Little information about the role of saliva in oral wound healing is found. The present study evaluates the healing of extraction wounds in desalivated rats. Experimental rats underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts. Maxillary left first molars were extracted. Rats were killed at 0. 1, 3, 5, 7. 10, 14. and 21 days after surgery and maxillae were prepared for light microscopy examination. Generally, a delay in socket healing in the desalivated rats was found. No differences were observed in blood clot formation. Replacement of the clot by granulation tissue was relatively slow concomitant with a longer inflammatory process. Bone formation kinetics were slower among the experimental rats.
Self- and commual-licking is a common phenomenon observed among mammals. This instinctive behavior becomes more pronounced after injury. Saliva may have some wound healing properties as it contains several immunobiologically active substances (1), such as immunoglobulins. antibacterial factors and growth promoting mediators which are delivered to the wound by licking. The effect of saliva on wound healing was first shown by HUTSON et al, (2). using a back skin wound in experimentally sialadenectomized mice. The rate of contraction of skin wounds was delayed if licking was avoided. Topical application of epidermal growth factor (EGF) or nerve growth factor (NGF) to the skin wound of sialadenectomized mice can correct most of the contraction delay observed after sialadenectomy. suggesting that EGF or NGF may be one of the wound healing factors in saliva (3, 4), The oral cavity is constantly bathed in saliva; however, little information is found on the effect of saliva on oral wound healing, SHEN et al, (5) reported a delay in gingival wound healing in sialadenectomized rats, but no alteration in healing was observed in tongue wounds. The process of wound healing after tooth extraetion has been extensively studied in human and experimental animals (6-11), WADE & FLEMING
(12) reported alteration of extraction wound healing in rats after ligation of
the salivary glands; however, the effect of salivary hypofunction on extraction wound healing has not been fully investigated. The purpose of the present study was to examine the healing of an extraction wound in a desalivated rat model. Material and methods
A total of 80. 2-month-old. male Sprague-Dawley rats, weighing approximately 200 g, were randomly divided into experimental and control groups. The experimental group underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts bilaterally, through a midventral incison (13), The control group was subjected to a sham-operation involving full exposure of the glands and subsequent incision closure with 3/0 silk. In both groups, the maxillary left first molars were extraeted immediately after surgery by a specially adapted mosquito forceps. Rats were fed a standard purina lab chow and water ad libitum. Five rats from each group were killed at 0, 1, 3, 5, 7, 10, 14, and 21 days. The maxillae were dissected and fixed in 10% formalin. Paraffin blocks were prepared after decalcification in 18% EDTA for2 wk. Serial sections, 6 |im. were cut in a mesio-distal plane to the maxillary molars. Only sections including the full length of the socket were stained with
Key words: desalivation: extraction: rat: teeth: wound healing. L. Bodner, School of Dental Medicine, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel Accepted for publication November 16, 1990
hematoxylin-eosin and examined with light microscopy, Histomorphometry - Quantitative microscopy was performed on a Visopan projection microscope (Reichert, Austria) at a magnification of x 40, A systemic grid with a point density of 1 point/cm- was overlayed on the projection screen. The area of various histologic parameters such as blood clot, necrosis, infiammation (as indicated by the presence of polymorphonuclear and mononuclear infiammatory cells), epithelialization, connective tissue formation and bone formation, was traced. The number of points within each compartment is an estimate of the area (14), Data calculations were performed as previously described (15), and presented as mean + standard error. Student's ttest was used to analyze the data. Results
The experimental procedure was without incident and no rats died during the postoperative period. No significant differences in food consumption, body weight or general well being were noted between the groups. The oral cavity of the desalivated rats were dry; small pieces of debris were found adjacent to the teeth and extraction site. Histomorphometric observations The histopathology of the healing socket wound followed the classical morphology kinetics. Immediately after extrac-
Wound healing in desalivated rat 177 tions, sockets were filled with blood clot. A rapid decrease of the blood clot was then noted and by day 5. it was almost dissolved. No significant differences were observed between the groups (Fig, 1), Between day 3 and day 7, necrotic tissue and infiammation were the most prominent histologic parameters seen in the sockets. The fraction area of the necrotic tissue in the sockets in the experimental group was double that of the eontrol group {P
Lipa Bodner\ Dan Dayan^ Doron Rothchild^ and llan Hammel^ Sections of 'Oral and Maxitlotacial Surgery, 'Oral Pathology and Oral Medicine, Maurice and Gabriela Goldschteger School ot Dental Medicine, ^Department ot Pathotogy, Sackter Facutty of Medicine, Tet Aviv University, Israel
Bodner L. Dayan D. Rothchild D. Hammel 1: Extraction wound healing in desalivated rats, .1 Oral Pathol Med 1991; 20: 176-8, Wound licking has been shown to promote extraoral wound healing among animals. Although the oral mucosa is bathed in saliva. Little information about the role of saliva in oral wound healing is found. The present study evaluates the healing of extraction wounds in desalivated rats. Experimental rats underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts. Maxillary left first molars were extracted. Rats were killed at 0. 1, 3, 5, 7. 10, 14. and 21 days after surgery and maxillae were prepared for light microscopy examination. Generally, a delay in socket healing in the desalivated rats was found. No differences were observed in blood clot formation. Replacement of the clot by granulation tissue was relatively slow concomitant with a longer inflammatory process. Bone formation kinetics were slower among the experimental rats.
Self- and commual-licking is a common phenomenon observed among mammals. This instinctive behavior becomes more pronounced after injury. Saliva may have some wound healing properties as it contains several immunobiologically active substances (1), such as immunoglobulins. antibacterial factors and growth promoting mediators which are delivered to the wound by licking. The effect of saliva on wound healing was first shown by HUTSON et al, (2). using a back skin wound in experimentally sialadenectomized mice. The rate of contraction of skin wounds was delayed if licking was avoided. Topical application of epidermal growth factor (EGF) or nerve growth factor (NGF) to the skin wound of sialadenectomized mice can correct most of the contraction delay observed after sialadenectomy. suggesting that EGF or NGF may be one of the wound healing factors in saliva (3, 4), The oral cavity is constantly bathed in saliva; however, little information is found on the effect of saliva on oral wound healing, SHEN et al, (5) reported a delay in gingival wound healing in sialadenectomized rats, but no alteration in healing was observed in tongue wounds. The process of wound healing after tooth extraetion has been extensively studied in human and experimental animals (6-11), WADE & FLEMING
(12) reported alteration of extraction wound healing in rats after ligation of
the salivary glands; however, the effect of salivary hypofunction on extraction wound healing has not been fully investigated. The purpose of the present study was to examine the healing of an extraction wound in a desalivated rat model. Material and methods
A total of 80. 2-month-old. male Sprague-Dawley rats, weighing approximately 200 g, were randomly divided into experimental and control groups. The experimental group underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts bilaterally, through a midventral incison (13), The control group was subjected to a sham-operation involving full exposure of the glands and subsequent incision closure with 3/0 silk. In both groups, the maxillary left first molars were extraeted immediately after surgery by a specially adapted mosquito forceps. Rats were fed a standard purina lab chow and water ad libitum. Five rats from each group were killed at 0, 1, 3, 5, 7, 10, 14, and 21 days. The maxillae were dissected and fixed in 10% formalin. Paraffin blocks were prepared after decalcification in 18% EDTA for2 wk. Serial sections, 6 |im. were cut in a mesio-distal plane to the maxillary molars. Only sections including the full length of the socket were stained with
Key words: desalivation: extraction: rat: teeth: wound healing. L. Bodner, School of Dental Medicine, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel Accepted for publication November 16, 1990
hematoxylin-eosin and examined with light microscopy, Histomorphometry - Quantitative microscopy was performed on a Visopan projection microscope (Reichert, Austria) at a magnification of x 40, A systemic grid with a point density of 1 point/cm- was overlayed on the projection screen. The area of various histologic parameters such as blood clot, necrosis, infiammation (as indicated by the presence of polymorphonuclear and mononuclear infiammatory cells), epithelialization, connective tissue formation and bone formation, was traced. The number of points within each compartment is an estimate of the area (14), Data calculations were performed as previously described (15), and presented as mean + standard error. Student's ttest was used to analyze the data. Results
The experimental procedure was without incident and no rats died during the postoperative period. No significant differences in food consumption, body weight or general well being were noted between the groups. The oral cavity of the desalivated rats were dry; small pieces of debris were found adjacent to the teeth and extraction site. Histomorphometric observations The histopathology of the healing socket wound followed the classical morphology kinetics. Immediately after extrac-
Wound healing in desalivated rat 177 tions, sockets were filled with blood clot. A rapid decrease of the blood clot was then noted and by day 5. it was almost dissolved. No significant differences were observed between the groups (Fig, 1), Between day 3 and day 7, necrotic tissue and infiammation were the most prominent histologic parameters seen in the sockets. The fraction area of the necrotic tissue in the sockets in the experimental group was double that of the eontrol group {P
