Assessment of the Efficacy and Safety of Oral Chlorhexidine Usage in the Prevention of Alveolar Osteitis

Bertolami, Charles N. Korean Academy of Oral Biology and the UCLA Dental 1997 International Journal of Oral Biology Vol.22 No.1

The occurrence of alveolar osteitis, or dry socket, is a common complication after extraction of teeth. Typically, it is characterized by disintegration of the blood clot contained within the postextraction alveolus (socket), leaving necrotic debris and exposed bone. The key symptom is severe pain beginning 2-5 days after surgery. Although efforts have been made at mitigating alveolar osteitis, none have been unequivocally accepted as effective. For this reason, research advancing chlorhexidine, an antiplaque agent, as a promising preventative for alveolar osteitis deserves special notice. However, controversy over the precise etiology of alveolar osteitis itself and inevitable differences in study design, conduct, and interpretation, makes it possible to find evidence in the literature that supports opposing conclusions concerning the efficacy of chlorhexidine for this purpose. The intent of this review article is to critically evaluate conflicting claims made for chlorhexidine in the context of alveolar osteitis and to discern this agent's legitimate value, if any, in dentoalveolar surgery. Review of the literature reveals that most studies dealing with chlorhexidine and alveolar osteitis fall into two broad categories: (1) Those in which chlorhexidine use is the primary study variable and alveolar osteitis the primary outcome measure and (2) those in which chlorhexidine use is ancillary or incidental to the overall goals of the study. The first category consists of studies that are generally well-designed, randomized, placebo-controlled, double-blinded, and focused specifically on the question of chlorhexidine as a preventative for alveolar osteitis. Studies in the first category all tend to show a distinct benefit to the use of chlorhexidine. In contrast, the second category of studies tend to be more diffuse and less useful in providing insight into the efficacy of chlorhexidine in preventing alveolar osteitis. Typically, the second category of studies leave multiple variables uncontrolled, involve multiple surgeons having varying levels of experience, do not represent patients on oral contraceptives equally in all study groups, may not employ a placebo control, or may employ placebo control that differs in more than one ingredient from the test solution. Such studies tend to support a lack of efficacy. The relative robustness of the former category of studies and the weakness of the latter favor the interpretation that chlorhexidine offers distinct clinical benefit when used as a measure for preventing alveolar osteitis.

Presence of CD44 on Human Cutaneous Microvascular Endothelial Cells

Le, Anh,Messadi, Diana V.,Bertolami, Charles N. Korean Academy of Oral Biology and the UCLA Dental 1997 International Journal of Oral Biology Vol.22 No.1

Angiogenesis is essential for wound healing and tissue repair. During the angiogenic process, the interaction between adhesive proteins, expressed on endothelial cell surfaces, and extracellular matrix components palys an important role in cell attachment, migration and proliferation. In this study, we examined the expression of CD44 (a putative hyaluronan receptor molecule) by dermal microvascular endothelial cells (DMECs) from normal skin, normal scar and keloid tissue. Tissue samples were obtained from biopsies of human normal skin, normal scar and keloid. Cultured DMECs were studied for expression of surface CD44 standard from by immunocytochemistry using anti-CD44 monoclonal antibody and anti-Factor Ⅷ as a positive marker for verification of the endothelial cell phenotype. CD44 gene expression was examined using Northern Blot analysis and synthesized cDNA probe for CD44 standard form. Our results indicate that dermal microvascular endothelial cells expressed the CD44 molecule at both transcriptional and translational levels, with keloids showing a higher level of CD44 gene expression than normal skin and normal scar. This suggests its possible role as a mediator of hyaluronan-induced cell migration.

Expression of VEGF Receptor by Human Dermal Microvascular Endothelial Cells

Le, Anh,Messadi, Diana V.,Charles Bertolami Korean Academy of Oral Biology and the UCLA Dental 1998 International Journal of Oral Biology Vol.23 No.1

Persistent microvascular hyperpermeability resulting in extravasation of fibrinogen products in the wound milieu serves as a provisional matrix and promotes angiogenesis and scar formation. Numerous studies elucidate a selective endothelial cell growth factor known as vascular endothelial growth factor (VEGF) which exhibits both in vitro and in vivo angiogenic capability and increases in vascular permeability at the wound site. VEGF exerts its biological function through distinct membrane-spanning tyrosine kinase receptors, FLT and KDR, which have been reported to be selectively expressed by vascular endothelial cells. In this study we examined the expression of VEGF receptors by cultured microvascular endothelial cells derived from human normal dermis and keloid scar. Frozen tissue samples and cultured microvascular endothelial cells were studied for the presence of VEGF binding sites using immunohistochemical and immunocytochemical stainings with VEGF, followed by anti-VEGF monoclonal antibody with appropriate negative control. VEGF receptor gene expression was examined using Northern blot analysis and synthesized cDNA probes for both KDR and FLT. Our results indicate that dermal microvascular endothelial cells derived from normal dermis and keloid scar expressed KDR as the major form of VEGF receptor, while FLT is not detectable. This suggests that KDR is the essential VEGF receptor in regulation of cellular proliferation and differentiation in cultured dermal microvascular endothelial cells.

The Role of Apoptosis in Keloid Formation

Messadi, Diana V.,Anna Jewett,Le, Anh,Steve Berg,Zhuang Wen,Bertolami, Charles N. Korean Academy of Oral Biology and the UCLA Dental 1998 International Journal of Oral Biology Vol.23 No.1

In traumatic injuries, hypertrophic scarring and keloid formation are serious derangements of healing that are defined primarily by an abnormal accumulation of extracellular matrix. The precise molecular and biochemical dysfunctions that lead to such conditions are still unknown. The role of apoptosis, a form of cell death, has recently been elucidated as playing a role in the transition between granulation tissue and scar formation. In this study we assessed the potential role of apoptosis in keloid formation. Normal skin and keloid tissues were immunolabeled for DNA strand breaks using an in situ end labeling fluorescein kit. Both types of tissue demonstrated apoptotic cells in the epidermis and papillary dermis. Quantitative analysis of apoptotic cells was performed using flow cytometry analysis on fibroblasts derived from normal skin and keloid tissues that were stimulated to undergo apoptosis by anti-Fas antibody and TNF-α. Results show that normal skin fibroblasts have a three-fold higher percentage of apoptotic cells than keloid fibroblasts.

Frequent Mutations of p53 and MTS1/CDK4I Tumor Suppressor Genes in Chinese Preneoplastic and Neoplastic Oral Tissues

Li, Sheng-Lin,Baek, Jeong-Hwa,Zhang, Kui-Hua,Min, Byung-Moo,Gujuluva, Chandrasekhar N.,Bertolami, Charles N.,Park, No-Hee Korean Academy of Oral Biology and the UCLA Dental 1996 International Journal of Oral Biology Vol.21 No.1

Aberrant expression and mutation in the p53 and MTS1/CDK41 genes were determined from 11 normal, 8 preneoplastic and 25 neoplastic oral tissues obtained from Beijing, China, using immunostaining, single strand conformational polymorphism analysis, and nucleotide sequencing. Normal tissue showed a negligible amount of p53 immunostaining, while 3 (38%) of 8 preneoplastic, and 16 (64%) of 25 cancer tissues demonstrated moderate to strong p53 immunostaining. Point mutations within exons 5 to 8 were not detected in normal tissue specimens, but were detected in 2 (25%) preneoplastic tissues and in 15 (60%) cancer specimens. OF the tissues with mutations, 2 (100%) preneoplatic and 14 (93%) cancer tissues contained a CGT to CAT mutation at codon 273 of p53 gene. One cancer tissue showed a silent mutation (CGC to CTC) at codon 283. Three cancer specimens containing a point mutation at codon 273 also showed additional silent mutations at codons 156, 157, or 275. These data indicate that p53 mutation is highly prevalent in tested preneoplastic and neoplastic oral tissues and that the codon 273 is the "hot-spot" for point mutations. The enhanced p53 immunostaining was, in general, closely associated with point mutations, but 1 (13%) preneoplastic sample and 5 (20%) neoplastic oral tissues not containing point mutations within exons 5 to 8 demonstrated enhanced immunostaining. Over 62% of preneoplastic and 80% of neoplastic oral tissues contained mutations in MTS1/CDK4I gene, but, unlike p53 mutations, the mutation pattern of MTS1/CDK4I gene was not specific. Two preneoplastic (25%) and 12 neoplastic (48%) tissues contained mutations in both p53 and MTS1/CDK4I genes, and 2 preneoplastic (25%) and 3 neoplastic (12%) tissues contained mutations neither in p53 nor in MTS1/CDK4I genes.

Genetic Instability and the Development of Human Oral Cancer

Park, No-Hee,Joseph McQuirer,Frederick Rutherford,Shin, Ki-Hyuk,Liu, Xuan,Guo, Wentong,Bertolami, Charles N. Korean Academy of Oral Biology and the UCLA Dental 1998 International Journal of Oral Biology Vol.23 No.1

We established an in vitro multistep oral carcinogenesis model by sequential exposure of normal human oral keratinocytes (NHOK) to "high risk" human papillomavirus (HPV) and chemical carcinogens. First, we immortalized primary NHOK by transfecting the cells with either cloned HPV-16 or HPV-18 genome. The immortalized human oral keratinocytes (HOK) were further transformed into tumorigenic cells when they were exposed to chemical carcinogens. However, under the same chemical carcinogen exposure, NHOK did not transform. Although the reason for these differences in normal and HPV-immortalized HOK's response to chemical carcinogens remains unknown, we postulate that it may be due to the differences in the cells' ability to maintain genomic integrity. Genomic integrity is normally maintained by the cell's ability (1) to assess the status of the genome at a given time point, (2) to signal cell cycle progression or arrest, and (3) to repair damaged DNA. Disruptions in any of these pathways may ultimately result in the loss of genomic integrity, a hallmark of neoplastic cells. We demonstrated that, in HPV-immortalized HOK, the E6 and E7 oncoproteins of "high risk" HPV disrupt cellular signals and perturb cell cycle control and DNA repair, particularly when challenged by genotoxic agents. Finally, the effect of "high risk" HPV on the stability of cellular chromosomes was indirectly determined by checking the mutation frequency using a shuttle vector plasmid in NHOK and cells harboring "high risk" HPV genome. We found that infection with "high risk" HPV tremendously enhanced the mutation frequency of the shuttle vector. These data indicate that, in NHOK, genomic integrity is maintained through controlling cell cycle progression and DNA repair when challenged by genotoxic stresses, but "high risk" HPV infection, such as HPV-16 or HPV-18, jeopardizes such cell cycle controlling and DNA repair capacities and causes genetic instability.