Drug-induced gingival hyperplasia: phenytoin, cyclosporine, and nifedipine

Oral Health Care for Children and Youth With Developmental Disabilities: Clinical Report

Oral health is an essential component of overall health for all individuals. The oral health of children and youth with developmental disabilities (CYDD) involves unique characteristics and needs of which pediatricians and pediatric clinicians can be aware. Risk for oral disease in CYDD is multifactorial and includes underlying medical conditions, medications, and ability to participate in preventive oral health care and treatment, and lack of access to providers is common for this population despite being eligible for Medicaid. Pediatric clinicians are uniquely positioned to support the oral health needs of CYDD and their families through the medical home. This clinical report aims to inform pediatric clinicians about the unique oral health needs of CYDD. It provides guidance on assessing caries risk and periodontal status using structured screening instruments; understanding dental trauma, the role of diet and caries risk, trauma prevention, and malocclusion; and providing anticipatory guidance on oral hygiene that includes tooth brushing, use of fluoridated toothpaste, assessing community water fluoridation, advocating for a dental home by 1 year of age, and transition to adult dental care as part of adolescent health care. It also highlights special considerations for dental treatment rendered under sedation or general anesthesia that CYDD may need. Pediatric clinicians can help reduce risk of CYDD developing dental disease by understanding the unique needs of their patients and their barriers to accessing oral health care in their community, communicating with the child's dental home, and advocating for safe and accessible dental procedures.

The Management of Drug-Induced Gingival Enlargement in a Patient With Preexisting Periodontitis

Antihypertensives such as amlodipine, which is a family of calcium channel blockers (CCBs), possess a limitation by causing gingival enlargement on long-term use. Gingival enlargement hinders the patient's oral hygiene maintenance and causes more plaque accumulation and inflammation. The severity of the condition is dependent on dose and duration. When untreated, this leads to functional and esthetic disabilities. This is a case report of amlodipine-induced gingival enlargement in a young, chronic periodontitis patient who was under 5 mg of amlodipine for six months. Upon diagnosis, the patient underwent periodontal surgery and supportive periodontal therapy, which significantly improved her periodontal health in a one-year follow-up period.

Expression of epithelial–mesenchymal transition-associated proteins and proliferating cell nuclear antigen in dihydropyridine-induced gingival overgrowth fibroblasts: A preliminary study

Background/purpose

The clinical features of dihydropyridine-induced gingival overgrowth (DIGO), including extracellular matrix accumulation and cell hyperplasia, are regulated by inflammatory factors (e.g., Interleukin-1β [IL-1β]) in combination with calcium channel blockers (e.g., nifedipine [Nif]). We speculated that IL-1β and Nif (IL-1β/Nif) may be the main factor modulating the proliferative potential and turnover of fibroblasts in DIGO.

Materials and methods

We cultured four DIGO fibroblast strains and analysed the possible effects of IL-1β/Nif treatments on epithelial-mesenchymal transition (EMT)-associated proteins. We developed short hairpin ribonucleic acids (shRNAs) and used them to explore the role of IL-1β/Nif in regulating proliferating cell nuclear antigen (PCNA) levels in DIGO tissues.

Results

Our results revealed that compared with control cells, DIGO cells stimulated with IL-1β/Nif had higher levels of the EMT-associated proteins Snail, Slug, and Twist. Moreover, both drugs enhanced androgen receptor (AR), Slug, and PCNA expression.

Conclusion

Taken together, our data indicate that proinflammatory cytokines in combination with calcium channel blockers can regulate the expression of EMT-associated proteins and increase the proliferative potential of DIGO fibroblasts.

Local Mucosal Flap for the Treatment of Gingival Defect After Gingival Fibromatosis Excision

Gingival fibromatosis (GF) is a rare condition of fibrous enlargement of the gingivae causing functional or aesthetic problems. We report a case of localized GF in a 51-year-old healthy male patient who presented in our department with localized gingival enlargement. We performed gingivectomy and restored the defect with a novel local transpositional mucosal flap with excellent functional and aesthetic results. This type of intervention is accompanied by short surgical time, provides predictable results, and should be considered in adult patients with large defects from sizable lesions.

Calcium channel blocker induced gingival enlargement following implant placement in a fibula free flap reconstruction of the mandible: a case report

Background

Gingival tissue enlargement is a common side effect of antiepileptic medications (e.g. phenytoin and sodium valproate), immunosuppressing drugs (e.g. cyclosporine) and calcium channel blockers (e.g. nifedipine, verapamil, amlodipine) (Murakami et al. 2018, Clin Periodontol 45:S17–S27, 2018). The clinical and histological appearances of lesions caused by these drugs are indistinguishable from one another (Murakami et al. 2018, Clin Periodontol 45:S17–S27, 2018). Drug-induced gingival enlargement is rarely seen in edentulous patients.

Case presentation

This case presents a 72-year-old female with a history of squamous cell carcinoma of the floor of the mouth treated with surgical excision and fibula-free flap reconstruction. Following the uncovering of osseointegrated implants placed in the fibular-free flap, the patient developed gingival enlargement of the floor of the mouth. Cessation of amlodipine and switching to an alternative medication lead to a resolution of the enlarged tissue.

Conclusions

This case illustrates that gingival enlargement can occur around dental implants, most notably in rehabilitation cases in patients who have had head and neck cancer. Clinicians should be aware of the risk of gingival enlargement in hypertensive patients taking calcium channel blockers prior to implant placement.

Transcriptional Analysis Reveals Key Genes in the Pathogenesis of Nifedipine-Induced Gingival Overgrowth

BACKGROUND

Nifedipine-induced gingival overgrowth (NGO) is a multifactorial pathogenesis with increased extracellular matrix including collagen and glycans, inflammatory cytokines, and phenotype changes of fibroblasts. However, the molecular etiology of NGO is not well understood. The objective of this study is to investigate the key genes in the pathogenesis of NGO.

METHODS

In this study, we examined the proliferation and migration abilities of fibroblasts derived from patients with chronic periodontitis, nifedipine nonresponder gingival overgrowth, gingival overgrowth caused by nifedipine, and healthy normal gingiva. We conducted RNA-Seq on these four groups of fibroblasts and analysed the differentially expressed genes (DEGs).

RESULTS

Fibroblasts derived from NGO patients had higher proliferation and migration abilities than those of the other groups. Protein-protein interaction network analysis indicated that TGFB2, ITGA8, ITGA11, FGF5, PLA2G4D, PLA2G2F, PTGS1, CSF1, LPAR1, CCL3, and NKX3-1 are involved in the development of NGO. These factors are related to the arachidonic acid metabolism and PI3K/AKT signaling pathways.

CONCLUSION

Transcriptional gene expression analysis identified a number of DEGs that might be functionally related to gingival overgrowth induced by nifedipine. Our study provides important information on the molecular mechanism underlying nifedipine-induced gingival overgrowth.

Phenytoin sodium-ameliorated gingival fibroblast aging is associated with autophagy

BACKGROUND AND OBJECTIVE

Human gingival fibrolasts aging is an important cause of periodontal disease. Phenytoin sodium (phenytoin) has a side effect of gingival hyperplasia and an effect on the autophagy progress. This study investigated whether the effect of phenytoin on aging gingival fibroblast is related to the autophagy pathway.

MATERIAL AND METHODS

The aging model of gingival fibroblast cell line HGF-1 was induced by hydrogen peroxide (H₂ O₂ ), and the treatment of phenytoin and 3-methyladenine (3-MA) was performed simultaneously. Cell viability, cell cycle, and intracellular calcium ion were measured by flow cytometry. Changes in expression of basic fibroblast growth factor (bFGF), P16^INK4A , P21^cip1 , and bFGF, P16^INK4A , P21^cip1 , LC3II, p62, and Beclin were tested by using reverse transcription polymerase chain reaction, western blot, and immunofluorescence staining.

RESULTS

The results showed that aging HGF-1 proliferation was inhibited by H₂ O₂ , gene, protein expression of bFGF, P16^INK4A , and P21^cip1 were decreased, autophagy-related proteins LC3II, p62, and Becline were decreased, and the proportion of G0/G1 phase and intracellular calcium ion of cell cycle was increased. Phenytoin treatment could recovery above changes, but the effect of phenytoin could be blocked by 3-MA.

CONCLUSION

We propose that phenytoin alleviates the aging of gingival fibroblasts induced by H₂ O₂ . This condition is related to the enhancement of autophagy pathway.

Drug-Induced Gingival Hyperplasia in Transplant Recipients

Gingival hyperplasia is a common occurrence in transplant recipients who are taking cyclosporine. This condition can be complicated when calcium channel blockers or phenytoin are added to the armamentarium of medications; it can be painful and may interfere with eating, speech, and appearance. Multiple mechanisms exist for gingival overgrowth. Prevention with appropriate oral hygiene appears important in controlling the inflammatory component and decreasing the severity of the overgrowth. Patients must be aware of the potential for the development of gingival hyperplasia and must follow up with regular professional cleanings. If the overgrowth persists, treatment options should be discussed between patients and their physician. Conversion from cyclosporine to tacrolimus, treatment with antibiotic therapy, and surgical excision or laser therapy are all potential therapies to consider.

Effect of nonsurgical periodontal therapy verses oral hygiene instructions on type 2 diabetes subjects with chronic periodontitis: a randomised clinical trial

Background

40 subjects with type 2 diabetes and moderate to severe CP were randomly distributed to groups receiving either NSPT or OHI. Periodontal parameters, glycosylated haemoglobin (HbA1c) and high-sensitivity C-reactive protein (hs-CRP) were evaluated at baseline, 2- and 3-months intervals.

Methods

40 subjects with type 2 diabetes and moderate to severe CP were randomly distributed to groups receiving either NSPT or OHI. Periodontal parameters, glycosylated haemoglobin (HbA1c) and high-sensitivity C-reactive protein (hs-CRP) were evaluated at baseline, 2- and 3-months intervals.

Results

15 subjects from NSPT group and 17 from OHI group completed the study. The difference in plaque index (PI) between NSPT and OHI groups were significant at 2 months recall (p = 0.013). There was no significant difference between NSPT and OHI group for all other clinical periodontal parameters, HbA1c and CRP levels. At 3 months post-therapy, periodontal parameters improved significantly in both groups with sites with probing pocket depth (PPD) < 4 mm reported as 98 ± 1.8% in NSPT group and 92 ± 14.9% in OHI group. Mean PPD and mean probing attachment loss (PAL) within the NSPT group reduced significantly from baseline (2.56 ± 0.57 mm, 3.35 ± 0.83 mm) to final visit (1.94 ± 0.26 mm, 2.92 ± 0.72 mm) (p = 0.003, p < 0.001). For OHI group, improvements in mean PPD and mean PAL were also seen from baseline (2.29 ± 0.69 mm, 2.79 ± 0.96 mm) to final visit (2.09 ± 0.72 mm, 2.62 ± 0.97 mm) (p < 0.001 for both). Similarly, HbA1c levels decreased in both groups with NSPT group recording statistically significant reduction (p = 0.038). Participants who demonstrated ≥ 50% reduction in PPD showed significant reductions of HbA1c and hs-CRP levels (p = 0.004 and p = 0.012).

Conclusion

NSPT significantly reduced PI at 2 months post-therapy as compared to OHI. Both NSPT and OHI demonstrated improvements in other clinical parameters as well as HbA1c and CRP levels.

Trial registration

ClinicalTrials.gov: NCT01951547.

Proliferative and inductive effects of Cyclosporine a on gingival fibroblast of child and adult

Background:

Gingival overgrowth is a serious side-effect that accompanies the use of Cyclosporin A (CsA). Up to 97% of the transplant recipient children, who were submitted to CsA therapy, have been reported to suffer from this side-effect. Several conflicting theories have been proposed to explain the fibroblast's function in CsA-induced gingival overgrowth. The aim of this study is to assess the proliferation of gingival fibroblasts and levels of released cytokines after being exposed to CsA, in both adults and pediatric groups, and to make a comparison between the results of the two groups.

Materials and Methods:

The adult fibroblast samples were derived from four healthy adults, aged 35 to 42 years and pediatric samples were obtained from four healthy children, age between four and eleven years. Tissue samples were plated in Dulbecco's Modified Eagle Medium (DMEM) containing 10% fetal bovine serum (FBS), Streptomycin and Penicillin. The samples were cultured in 25 cm² plates containing 5% CO2, and incubated at 37°C. The cells used for all the experiments were at the fourth passage. The concentration of PGE₂, IL-1β, IL-6, IL-8, TNF-α, and TGF-β₁ was determined by the enzyme-linked immunosorbent assay (ELISA) and the proliferation rate was assessed by the MTT assay. Alpha error levels were set as 0.05.

Results:

CsA stimulated significantly higher levels of IL-6, IL-8 and TGF-β₁ in adult gingival fibroblasts than it did in the control group; whereas, the expression of IL-1β and PGE₂ in the fibroblasts exposed to CsA was significantly weaker (P < 0.05). The fibroblasts in the two groups did not reveal any noticeable difference in the production of TNF-α. Furthermore, cell proliferation in the CsA group was not significantly higher than that in the control group. No significant differences in cytokines TNF-α and IL-1β were noted between the two groups. The results indicated that CsA stimulated cell proliferation in the pediatric fibroblast cell line. Comparison between the results in the adult and pediatric groups demonstrated that the levels of IL-1β, IL-6, IL-8, and PGE₂ were significantly higher in the pediatric group than in the adult group; however, statistics showed no significant difference in the levels of TNF-α and TGF-β₁ and CsA-induced proliferation between these two groups.

Conclusions:

The mechanism of a CsA-induced fibroblast overgrowth may converge on the steps involving fibroblast proliferation and cytokine network including IL-6, IL-8, IL-1β, TGF-β₁, and PGE₂, in both adults and pediatrics. As the prevalence and intensity of drug-induced gingival overgrowth is more serious in the pediatrics. As group than in adults, we suggest that more studies be conducted on the pediatric group.

Calcium channel blocker-induced gingival enlargement

Despite the popularity and wide acceptance of the calcium channel blockers (CCBs) by the medical community, their oral impact is rarely recognized or discussed. CCBs, as a group, have been frequently implicated as an etiologic factor for a common oral condition seen among patients seeking dental care: drug-induced gingival enlargement or overgrowth. This enlargement can be localized or generalized, and can range from mild to extremely severe, affecting patient's appearance and function. Treatment options for these patients include cessation of the offending drug and substitution with another class of antihypertensive medication to prevent recurrence of the lesions. In addition, depending on the severity of the gingival overgrowth, nonsurgical and surgical periodontal therapy may be required. The overall objective of this article is to review the etiology and known risk factors of these lesions, their clinical manifestations and periodontal management.

Phenytoin-induced gingival overgrowth

Gingival overgrowth is a common adverse effect of therapy with Phenytoin, having important medical and cosmetic implications. Poor periodontal hygiene is an important risk factor for severity of Phenytoin-induced gingival overgrowth (PIGO), which is a time-dependent process. There is complex interplay of altered fibroblast biology, connective tissue turnover, inflammatory processes, and growth factors on a background of genetic susceptibility to produce increase in various components of interstitial matrix in PIGO tissue. Treatment options have included change of PHT to another anti-seizure drug, measures to improve periodontal hygiene and gingivectomy. There is conclusive evidence that folic acid supplementation significantly decreases the incidence of PIGO.

Expression of TNF-α and RANTES in drug-induced human gingival overgrowth

Objectives:

Regulated on activation, normal T cell expressed and secreted (RANTES) is a chemokine that is produced by fibroblasts, lymphoid and epithelial cells of the mucosa in response to various external stimuli. RANTES expression has been demonstrated in a variety of diseases characterized by inflammation, including asthma, transplantationassociated accelerated atherosclerosis, endometriosis and fibrosis. RANTES mRNA is quickly up-regulated by tumor necrosis factor (TNF)-α stimulation. Cyclosporine A (CsA) is widely used in organ transplant patients, often causing various side-effects including gingival overgrowth, which is fibrotic in nature. This study was carried out to assess the mRNA expression of TNF-α and RANTES in healthy individual, chronic periodontitis and CsAinduced gingival overgrowth tissues.

Materials and Methods:

Gingival tissue samples were collected from chronic periodontitis, CsAinduced gingival overgrowth patients and healthy individuals. Total RNA was isolated and reverse transcription polymerase chain reaction (RT-PCR) was performed for TNF-α and RANTES expression.

Results:

The results suggest that CsAinduced gingival overgrowth tissues expressed significantly increased TNF-α and RANTES compared to control and chronic periodontitis.

Conclusion:

The findings of the present study suggest that CsA can modify the expression of TNF-α and RANTES in drug-induced human gingival overgrowth.

Clinical assessment of nifedipine-induced gingival overgrowth in a group of brazilian patients

Although it has been established that nifedipine is associated with gingival overgrowth (GO), there is little information on the prevalence and severity of this condition in the Brazilian population. The aim of this study was to assess the occurrence of nifedipine-induced GO in Brazilian patients and the risk factors associated using a Clinical Index for Drug Induced Gingival Overgrowth (Clinical Index DIGO). The study was carried out on 35 patients under treatment with nifedipine (test group) and 35 patients without treatment (control group). Variables such as demographic (age, gender), pharmacological (dose, time of use), periodontal (plaque index, gingival index, probing depth, clinical insertion level, and bleeding on probing), and GO were assessed. Statistical analysis showed no association between GO and demographic or pharmacological variables. However, there was an association between GO and periodontal variables, except for plaque index. According to our study, the Clinical Index DIGO can be used as a parameter to evaluate GO. Therefore, we conclude that the presence of gingival inflammation was the main risk factor for the occurrence of nifedipine-induced GO.

An uncommon presentation of an inflammatory gingival enlargement--responding to non-surgical periodontal therapy

BACKGROUND

The various clinical manifestations of inflammatory gingival enlargement reported are more or less similar regardless of the underlying aetiological factors. Unusual presentation and unknown aetiology pose a diagnostic challenge for a periodontist.

METHODS

A 34-year-old Indian woman presented with the complaint of gum swelling that was sessile, lobulated, soft in consistency and bluish red in colour with ulcerated surface in some region, which was covered by the necrotic slough. This type of enlargement was unusual and some underlying systemic pathology was suspected. But a written consultation from her physician confirmed her systemic health, which was based on clinical, radiological and haematological investigations. Histopathological examination confirmed the diagnosis of inflammatory gingival enlargement. Patient was treated with oral hygiene instructions, scaling and root planning.

RESULT

Within a month of conventional periodontal therapy, gum enlargement reduced markedly and patient was put on oral hygiene maintenance programme.

CONCLUSION

Periodontal therapy is diagnosis-driven and, to the extent possible, should address all the possible factors that impact development and progression of diseases that may affect periodontal tissue. In plaque-induced periodontal diseases, non-surgical periodontal therapy is still a gold standard among all the therapies available.

Proteomic analysis in cyclosporin A-induced overgrowth of human gingival fibroblasts

Cyclosporin A (CsA) has been used as an immunosuppressive drug to prevent organ transplant rejection and to treat autoimmune diseases. CsA has a proliferative effect on human gingival fibroblasts (HGF) in vitro. However, the molecular mechanisms underlying CsA-induced proliferation in HGF remain to be elucidated. This study was aimed to investigate the CsA responsive proteins in HGF using systematic proteomic approach. Cell viability was determined by MTT assay and reactive oxygen species (ROS) was measured by fluorescent spectrometer. Proteins profiled by two-dimensional gel electrophoresis (2-DE) were identified by matrix-assisted laser desorption ionization time-of flight (MALDI-TOF) and electrospray ionization quadrupole time-of-flight mass spectrometry (EIQ-TOF MS). To confirm the expression changes of proteins by proteomics analysis, Western blot was performed using specific antibody. CsA increased the cell viability of HGF in a dose- and time-dependent manner. Significantly, seventeen proteins were overexpressed in the CsA-treated HGF, whereas three proteins were found to be expressed less than the untreated cells. The identified proteins were mainly related with cell proliferation, metabolism, and oxidation. The overexpression of peroxiredoxin 1 (Prx 1) confirmed by Western blotting and reduction of cytosolic reactive oxygen species (ROS) levels in the CsA-treated HGF demonstrated that Prx 1 may play a crucial role in the HGF proliferation induced by CsA. Upregulation of Galectin 3 in CsA-treated HGF indicated that it is related to CsA-induced proliferation. These proteomic analysis data will provide an efficient approach in understanding the mechanisms of HGF proliferation by CsA.

Drug-induced gingival hyperplasia and scaffolds: they may be valuable for horizontal food impaction

Food impaction is a severe clinical trouble that bothers most people especially middle aged and old people. It is reported that the rate of food impaction is 92.2%. The incidence of 40-59 years old is 98.9%. It is a disease of high prevalence in population. It has influenced people's social intercourse and everyday life because it may cause halitosis, gingivalitis, periodontitis, gingival abscess, alveolar bone absorption, root caries, eventually lead to severe results from teeth loose to deletion and so on. Several reasons are involved with food impaction such as gingival recession, periodontal disease, caries, age, excessive attrition, etc. Food impaction can be divided into two kinds: vertical and horizontal food impaction. At present, there are some clinical methods such as crown or dental filling for vertical one, but horizontal food impaction is still difficult to deal with. Though some methods are being adopted like making crowns and removable obstructers, the problems have never been settled effectively for the injury to teeth and inconvenience of these treatments. Here we put forward a hypothesis that periodontal tissues can regenerate much the same as normal situation by way of using drug to induce gingiva hyperplasia initiatively and implanting scaffolds. Then horizontal food impaction will be cured when the interproximal clearance is filled with periodontal tissues. It will bring the patient hope.

Non-surgical treatment of gingival overgrowth induced by nifedipine: a case report on an elderly patient

Drug-induced gingival overgrowth (DIGO) is a significant problem for periodontologists and this side effect is frequently associated with three particular drugs: phenytoin, cyclosporin A and nifedipine. A case report of gingival overgrowth induced by nifedipine in an elderly patient treated with non-surgical periodontal therapy is described. A 75-year-old male with generalised gingival overgrowth reported the problem of oral malodour and significant gingival bleeding. The medical history revealed a controlled hypertensive state and Cerebral Vascular Accident (CVA) 3 years prior to consultation. The diagnosis was gingival overgrowth associated with nifedipine, no other risk factors being identified. The patient had been taking nifedipine for 18 months, but after the consultation with the patient's doctor, nifedipine was suspended, as the hypertension was controlled. Treatment consisted of meticulous oral hygiene instruction, scaling, root surface instrumentation and prophylaxis. Six months after the first intervention, clinical parameters revealed a significant improvement with a considerable reduction in gingival overgrowth, demonstrating the effect of non-surgical periodontal therapy in severe cases of gingival overgrowth. Non-surgical treatment of DIGO is a far less invasive technique than surgical approaches and has demonstrated an impressively positive treatment response. It should therefore be considered as a first treatment option for DIGO.

Do MMP-1 levels of gingival fibroblasts have a role in the gingival overgrowth of cyclosporine-treated patients?

The aim of this study was to compare the matrix metalloproteinase-1 (MMP-1) levels in gingival fibroblast cultures derived from two groups of renal transplant patients receiving cyclosporine (CsA) who exhibit gingival overgrowth and who have healthy periodontium. Gingival fibroblasts obtained from four patients with CsA-induced gingival overgrowth (CsA-GO) and four patients who receive CsA but have healthy periodontium were incubated with increasing concentrations of CsA and cultured for 72 hours. Expression levels of MMP-1 in all the groups were measured four times at 0, 24, 48, and 72 hours by the Rapid Collagenase Assay Kit. No significant difference was seen at baseline. As the CsA concentration and the duration in the cell media increased, the CsA-GO showed that fibroblasts displayed significantly suppressed MMP-1 levels with respect to the baseline, at which fibroblasts from CsA patients with healthy periodontium exhibited the same result as at the highest CsA concentration. Results of this study indicated that CsA therapy did not have a significant effect on MMP-1 levels. Since the overall pathogenesis of drug-induced gingival hyperplasia has been accepted as multifactorial, down-regulation of MMP-1 expression may play a minor role.

Drug-induced gingival enlargement - Part II. Antiepileptic drugs: not only phenytoin is involved

INTRODUCTION: Gingival enlargement is the term now used to describe medication-related gingival overgrowth or gingival hyperplasia, a common reactionary phenomenon that occurs with the use of several types of therapeutic agents, including antiepileptic drugs. This disorder has been recognized since 1939, shortly after the introduction of phenytoin. METHODS: Review of literature concerning etiology, pathogenesis and management of antiepileptic drug induced gingival enlargement. CONCLUSIONS: It is important that neurologists become aware of the potential etiologic agents of antiepileptic drug induced gingival enlargement and its characteristic features in order to be able to prevent, diagnose and successfully manage it.

Endothelin-1 and its receptors ET(A) and ET(B) in drug-induced gingival overgrowth

BACKGROUND

The purpose of this study was to study the expression of endothelin-1 (ET-1) and its receptors ETA and ETB in normal human gingiva and cyclosporin-induced gingival fibroblasts.

METHODS

Gingival samples were collected from eight normal healthy individuals, eight patients with periodontitis, and eight patients with cyclosporin A (CsA)-induced gingival overgrowth. Total RNA was extracted from tissue samples, and reverse transcriptase-polymerase chain reaction was performed for ET-1, ETA, and ETB. ET-1 protein was estimated from the tissues by enzyme-linked immunosorbent assay. The expression of ET-1 and its receptors was also examined in gingival fibroblast cells treated with CsA.

RESULTS

ET-1 mRNA expression was significantly higher in patients with CsA-induced gingival overgrowth (P <0.001) than in patients with periodontitis and the controls. ETA mRNA was expressed more than the ETB in all examined samples. In human gingival fibroblasts, ET-1 expression was increased with CsA incorporation compared to controls (P <0.001).

CONCLUSION

These results suggest that CsA can modulate the expression of ET-1 in gingival fibroblasts and CsA-induced gingival overgrowth.

Hiperplasia gengival medicamentosa: parte I

INTRODUÇÃO: A hiperplasia gengival pode ser causada por alguns medicamentos, entre os quais a fenitoína. Torna-se importante a prevenção, o diagnóstico precoce e o seguimento de pessoas com epilepsia por profissional da área odontológica. OBJETIVO: O presente artigo tem o propósito de discutir os aspectos etiológicos, clínicos e terapêuticos da hiperplasia gengival medicamentosa. METODOLOGIA: Revisão da literatura. RESULTADOS: A necessidade de aliar o tratamento odontológico ao tratamento medicamentoso é enfatizada como forma de prevenir e/ou minimizar a hiperplasia gengival medicamentosa conseqüente à ação farmacológica de algumas drogas e fatores irritantes localizados nos tecidos dentais e periodontais.

Cyclosporin-induced gingival overgrowth in children

Cyclosporin is a potent immunosuppressant drug commonly used to prevent organ transplant rejection. In recent years, there has been a widening of its therapeutic use and an increase in the number of patients undergoing transplantation. Gingival overgrowth is one of several oral side-effects of cyclosporin, with a quoted prevalence of between 8% and 100%. There is continued debate over the factors which modify the degree of overgrowth, including individual sensitivity, age, dose of drug, duration of drug therapy and the presence of dental plaque. The exact mechanism of gingival overgrowth is still being debated, but appears to be caused by a combination of the proliferation of fibroblasts within the gingival tissue, an increase in the deposition of collagen and extracellular matrix, and a decrease in phagocytosis with a net gain in gingival tissue mass. A number of treatment options are utilized in the treatment of gingival overgrowth, including CO2 laser surgery, improved oral hygiene, the use of antibiotics such as metronidazole and azithromycin, and surgical intervention. In the clinical application of cyclosporin, there is little correlation between cyclosporin dose, serum trough levels and total exposure to the drug, making it difficult to achieve the desired therapeutic response. These problems were previously further complicated by the variability of absorption of the drug via the gastrointestinal tract. The original cyclosporin formulation, Sandimmune, was replaced by a new formulation, Neoral, which has a more reliable absorption, and gives a closer correlation between trough concentration levels and individual bioavailability. There is a conflict of opinion over whether or not the side-effect profile of Neoral varies from its precursor Sandimmune. It has yet to be seen whether the increased bioavailability of Neoral will result in an increased severity and prevalence of gingival overgrowth. An alternative immunosuppressant drug, tacrolimus, which is a macrolide antibiotic with a different side-effect profile, has emerged as a substitute for cyclosporin in organ transplantation. However, there have been conflicting reports of its side-effects and its capacity to cause gingival overgrowth.

Felodipine-influenced gingival enlargement in an uncontrolled type 2 diabetic patient

BACKGROUND

The potential of calcium channel blockers (CCBs) to induce gingival enlargement (GE) as well as the influence of diabetes mellitus on periodontal tissues has been well documented. This case report documents a conservative clinical approach to the management of felodipine-influenced gingival enlargement and displays a clinical and histologic case of felodipine-influenced GE in an undiagnosed type 2 diabetic patient.

METHODS

At the initial examination, a medical consultation was requested and two incisional biopsies were taken for pathological evaluation. The patient was diagnosed with uncontrolled type 2 diabetes. Felodipine was withdrawn and the diabetes was controlled before dental treatment was initiated. The patient then underwent selective extractions and full-mouth scaling and root planing as well as oral hygiene instructions. No surgical therapy was indicated.

RESULTS

The histological results demonstrated the presence of elongated rete pegs; fibrous hyperplasia; a low-grade chronic inflammatory infiltrate, predominantly consisting of lymphocytes; and collagen bundle groups randomly distributed. These features were similar to those present in other drug-influenced GE. Clinical results have demonstrated almost complete resolution of GE after the withdrawal of felodipine and the control of diabetes. Further improvements were seen after scaling and root planing and oral hygiene instructions. No recurrences were noted 12 months after initial therapy.

CONCLUSIONS

This report demonstrated that the control of systemic factors seemed to have the most influence on success for this particular case. Since the control of diabetes was managed at the same time as the felodipine withdrawal, it remains difficult to speculate how these two factors impacted both the severity of the GE and the therapeutic results. More importantly, the conservative treatment rendered demonstrated the stability of periodontal status during maintenance phase and the avoidance of surgical interventions.

Gingival overgrowth in children: epidemiology, pathogenesis, and complications. A literature review

Gingival overgrowth is the enlargement of the attached gingiva due to an increased number of cells. The most prevalent types of gingival overgrowth in children are drug-induced gingival overgrowth, hereditary gingival fibromatosis (HGF), and neurofibromatosis I (von Recklinghausen disease). Gingival overgrowth induced by drugs such as phenytoin, nifedipine, and cyclosporin develops due to an increase in the connective tissue extracellular matrix. According to epidemiologic studies, it is more prevalent in male children and adolescents. There is an additive effect of those drugs on the degree of gingival overgrowth. Genetic heterogeneity seems to play an important role in the development of the disease. Functional difficulties, disfigurement, increased caries, and delayed eruption of permanent teeth are the main complications of drug-induced gingival overgrowth. HGF is the most common syndromic gingival enlargement in children. This autosomal dominant disease usually appears at the time of eruption of permanent dentition. Histologically, it is characterized by highly collagenized connective tissue. The most important complications are drifting of teeth, prolonged retention of primary dentition, diastemata, and poor plaque control. Neurofibromatosis I is an autosomal dominant disease more common in mentally handicapped individuals. Gingival overgrowth is caused by the formation of plexiform neurofibromas in the connective tissue of the gingiva. Plexiform neurofibromas are pathognomonic of the disease and consist of hypertrophic nerves arranged as lobules in the connective tissue. Complications of the disease are multiple and severe due to neurofibromas and their occasional malignant transformation.

Mechanisms and management of gingival overgrowth in paediatric transplant recipients: a review

Increasing numbers of children are receiving solid organ transplants namely kidney, liver, heart and lung. Patient survival rates following such transplants are essentially good with much of the success attributable to the development of Cyclosporine A (CyA), an immunosuppressive drug, that minimizes organ rejection. However the gingival overgrowth (GO) associated with the use of CyA is not only disfiguring but in paediatric recipients, may interfere with normal oral development and function.

OBJECTIVE

The aim of this review is to summarize current knowledge concerning the aetiology, pathogenesis and management of gingival overgrowth.

METHODS

Literature pertaining to gingival overgrowth is reviewed with particular reference to the paediatric population. Emphasis is placed on summarizing the evidence pertaining to the effectiveness of intervention.

CONCLUSION

CyA undoubtedly causes gingival overgrowth, the effects and levels of which appears to be more severe in younger patients. There is conflicting evidence as to the effectiveness of oral hygiene regimes, antibiotics and surgery in reducing overgrowth. The introduction of an alternative immunosuppressive agent (Tacrolimus) offers potential as it does not appear to cause overgrowth, although research to date is limited by the small sample size of many of the studies. This is an area in which multicentre studies would be of great value.

Drug-induced gingival hyperplasia in transplant recipients

Gingival hyperplasia is a common occurrence in transplant recipients who are taking cyclosporine. This condition can be complicated when calcium channel blockers or phenytoin are added to the armamentarium of medications; it can be painful and may interfere with eating, speech, and appearance. Multiple mechanisms exist for gingival overgrowth. Prevention with appropriate oral hygiene appears important in controlling the inflammatory component and decreasing the severity of the overgrowth. Patients must be aware of the potential for the development of gingival hyperplasia and must follow up with regular professional cleanings. If the overgrowth persists, treatment options should be discussed between patients and their physician. Conversion from cyclosporine to tacrolimus, treatment with antibiotic therapy, and surgical excision or laser therapy are all potential therapies to consider.

Treatment of plaque-induced gingivitis, chronic periodontitis, and other clinical conditions

The inflammatory components of plaque induced gingivitis and chronic periodontitis can be managed effectively for the majority of patients with a plaque control program and non-surgical and/or surgical root debridement coupled with continued periodontal maintenance procedures. Some patients may need additional therapeutic procedures. All of the therapeutic modalities reviewed in this position paper may be utilized by the clinician at various times over the long-term management of the patient's periodontal condition.

Cyclosporin-induced gingival overgrowth at the newly formed edentulous ridge in rats: a morphological and histometric evaluation

BACKGROUND

Since cyclosporin A (CsA)-induced overgrowth seldom occurs at sites distant from teeth, the periodontal ligament has been considered significant. The aim of this study was to examine overgrowth occurrence at the edentulous ridge--the sites without the ligament--after CsA therapy in rats.

METHODS

After extracting all right maxillary molars, 16 Sprague-Dawley rats underwent a 2-week healing period. The animals were separated into CsA and control groups. CsA rats received 15 mg/kg of CsA by gastric feeding for 4 weeks, while the control group received only mineral oil. At the end of study, all animals were sacrificed and stone models were immediately obtained by rubber-based impressions. The edentulous ridge morphology, including the bucco-lingual width and the vertical height, was measured on the models. For histometry, 10 sections were selected from the edentulous ridge of each animal after undecalcified tissue preparation. The soft tissue areas of the edentulous ridge and the trabecular bone morphology of the dental alveolus were measured.

RESULTS

CsA therapy produced a significant increase of the ridge width and height, measured from the stone models, when compared to the control group. Under histometry, CsA resulted in a significant increase of the epithelium, connective tissue, and total soft tissue areas. The measured trabecular bone volume was affected by both examining factors: the drug therapy and the location of the dental alveolus. CsA therapy produced a significant loss of bone volume but a significant increase of the bone-specific surface area. Although the mean osteoid volume was similar between CsA and control groups, a significant decrease of the fractional formation surface in the CsA group was revealed.

CONCLUSIONS

An enlarged edentulous ridge and an altered dental alveolar bone morphology were observed in CsA-treated animals at the end of the study; therefore, we suggest that CsA may induce not only a soft tissue overgrowth but also an alveolar bone alteration at the edentulous ridge. The hypothesis that tooth or periodontal ligament is an essential component for the overgrowth development is questioned.

Periodontal disease and atherosclerotic cardiovascular disease: confounding effects or epiphenomenon?

Recent evidence suggests that periodontal disease may predispose to atherosclerotic cardiovascular disease. Data support mechanisms of host-derived local and systemic proinflammatory responses similar to atherosclerosis, consisting of monocytic-derived cytokines and other inflammatory mediators, which are induced by periodontal pathogens and its endotoxin, lipopolysaccharide. These mechanisms may contribute to the start of vascular endothelial dysfunction and further sequelae leading to atherosclerosis. Experimental evidence and biologic plausibility appear to support this proposal. However, clinical evidence from a MEDLINE search from January 1966-December 1999 proposed a weak or no correlation primarily due to confounding factors. The aim of care is to reduce vulnerable pathogens from the infected periodontium by standard treatment; however, new approaches appear promising. Increased awareness of a potential link among infective agents, immunoinflammatory processes, and atherosclerosis may clarify clinical implications.

Effects of combined oral treatments with cyclosporine A and nifedipine or diltiazem on drug-induced gingival overgrowth in rats

BACKGROUND

Cyclosporine A (CsA) and calcium channel blockers induce gingival overgrowth in humans and animals. Recently, nifedipine and diltiazem have often been used to control CsA-related hypertension in organ transplant patients. The purpose of this study was to examine the effects of a combined oral treatment of CsA and nifedipine or diltiazem on the severity of gingival overgrowth in rats.

METHODS

Fifteen-day-old Fischer rats were treated orally with single or combined applications of CsA, nifedipine, and/or diltiazem for 40 days; and induced gingival overgrowth, rat growth, and blood drug levels were compared among the different experimental groups. The experiment consisted of 6 groups: one control group (group A) and 5 test groups treated with CsA (group B), nifedipine (group C), and diltiazem (group D), as well as those concurrently treated with CsA and nifedipine (group E), and CsA and diltiazem (group F). Gingival overgrowth was determined by measuring the depth of the gingival sulcus.

RESULTS

The mandibular buccal gingival sulcus depth of group A was 365 +/- 41.2 microm. Among the test groups, the most remarkable gingival overgrowth was seen in group E (1,020 +/- 63.3 microm), followed by group F (895 +/- 43.8 microm), group B (870 +/- 48.3 microm), group C (525 +/- 116 microm), and then group D (505 +/- 83.2 microm). Rat body weight gain was reduced significantly by oral CsA treatment. Neither nifedipine nor diltiazem suppressed rat growth when used independently; however, rat growth reduced by CsA was further suppressed by a combined use of diltiazem, but not nifedipine. CsA blood levels were reduced by concurrent oral treatment with nifedipine or diltiazem along with the blood levels of those calcium channel blockers when treatment was in combination with CsA.

CONCLUSIONS

These results suggest that gingival overgrowth is induced in rats as a side effect of CsA, nifedipine, or diltiazem, and the combined use of these drugs influences rat growth, blood drug levels, and the severity of gingival overgrowth.

Medically induced gingival hyperplasia

Gingival hyperplasia or gingival overgrowth is a common occurrence in patients taking phenytoin, cyclosporine, or calcium channel blockers. Speech, mastication, tooth eruption, and aesthetics may be altered. Controlling the inflammatory component through an appropriate oral hygiene program may benefit the patient by limiting the severity of the gingival overgrowth. In patients in whom gingival overgrowth is present or may be anticipated, recognition of this condition and referral to a general dentist or periodontist are appropriate steps to management. The physician's awareness of the potential for development of overgrowth and the dental practitioner's role in attempting to prevent or minimize this problem are important aspects. In this article, we discuss the medications associated with gingival hyperplasia and describe appropriate recommendations.

Drugs and oral disorders

This chapter affirms that drugs and medicaments may have a profound effect on the periodontal structures. In some instances, such as drug-induced melanosis, the effect may be insignificant to the health of the patient. In other circumstances, drug-induced disorders may initiate painful, destructive disease processes that will not be successfully managed unless the causal role of drugs is recognized and altered. Finally, the clinician must remain aware of the contribution of drug-induced xerostomia and smoking to increased susceptibility to dental and periodontal diseases.

Nifedipine-induced gingival overgrowth in rats: brief review and experimental study

The first case report of gingival overgrowth induced by nifedipine (NIF), a calcium-beta blocker, was in 1984. However, the association between gingival alterations and the drug therapy of sodium diphenyl hydantoinate was initially described in 1939. The purpose of the experimental study was to examine the effect of NIF on gingival morphology in an animal model. Forty-five male Sprague-Dawley rats were randomly divided into 3 groups. Animals in each group daily received NIF in dimethyl sulfoxide by gastric feeding at a dosage of 0 (control), 30, or 50 mg/kg body weight for 9 weeks. Gingival gross morphology was assessed tri-weekly from stone models obtained from the mandibular incisal region. Animals were sacrificed at the end of study and tissue blocks were processed for histopathologic and histometric evaluation. Histometric analysis was performed at 5 selected tissue levels. Macro- and microscopic significantly increased gingival dimensions were demonstrated in NIF-treated animals compared to control. Although a fibrovascular tissue was observed in the tooth-gingiva interface for both NIF-treated and control animals, it was thicker and appeared earlier in NIF-treated animals. The results of the present study suggest that gingival overgrowth can be induced by NIF in rats and that the gingival overgrowth appears dose dependent.

Surgical treatment of cyclosporine A- and nifedipine-induced gingival enlargement: gingivectomy versus periodontal flap

The purpose of this study was to compare probing depth resolution achieved by gingivectomy and periodontal flap techniques in the treatment of cyclosporine A- and nifedipine-induced gingival enlargement. Ten kidney transplant patients who were receiving cyclosporine A and nifedipine for at least 6 months participated in the study. Five patients were randomly assigned to the gingivectomy group and 5 patients to the periodontal flap group. Only anterior segments of the oral cavity (canine to canine) were surgically treated. Clinical measurements, including probing depths, plaque index, and gingival sulcus index, were taken at baseline, 6 weeks, 6 months, and 1 year. Results showed that probing depths, while similar for both groups in the first 6 weeks of the study, were significantly shallower for the periodontal flap group when compared to the gingivectomy group at 6 months (2.48 +/- 0.34 mm versus 4.87 +/- 0.79 mm, respectively) and 1 year (322 +/- 0.65 mm versus 6.40 +/- 1.02 mm, respectively). Within its limitations, this study suggests that the pocket reduction achieved by the periodontal flap may be sustained for longer periods of time than by the gingivectomy technique in the treatment of cyclosporine A- and nifedipine-induced gingival enlargement.

Efficacy of azithromycin in the treatment of cyclosporine-induced gingival hyperplasia in renal transplant recipients

BACKGROUND

Gingival hyperplasia (GH) is a common side effect of cyclosporine . Azithromycin (Zithromax; AZI) is a macrolide antibiotic reported in case studies to reduce cyclosporine-induced gingival hyperplasia (CIGH) in renal transplant recipients (RTR).

METHODS

The efficacy of AZI to treat CIGH in RTR was examined in a double-blind, randomized crossover trial. Patients (n=17) with CIGH were randomized to receive AZI and a matching placebo in alternate order for 5 days, separated by a 2-week washout period. Follow-up visits were conducted at week 6 and week 12. Changes in GH were evaluated by measuring the clinical gingival sulcus depths, tooth length, and the length of the interdental papillae to the cementum-enamel junction of two teeth in each of the four quadrants.

RESULTS

Significant improvements were observed in all three types of periodontal measurements, representing reductions of gingival tissue above the medial aspect of the tooth, of the gingival sulcus depth, and of the length of the interdental papillae. Patients reported an improvement in gum bleeding. AZI was well tolerated, and 67% of the patients reported that the treatment was at least somewhat useful.

CONCLUSIONS

AZI should be considered for RTR with CIGH.

Mucocutaneous features of autoimmune blistering diseases

This review will describe adult onset mucocutaneous/autoimmune diseases that involve defects in cell-to-cell, cell-to-matrix, or cell-to-basement membrane adhesion. Included in this group are pemphigus, cicatricial pemphigoid, linear IgA bullous dermatosis, epidermolysis bullosa acquisita, and bullous systemic lupus erythematous. Detection and treatment of blistering disorders that manifest early in the oral cavity may prevent widespread involvement of skin. During the past few years, targets of autoantibodies have been clarified and new targets have been identified, allowing better understanding of the pathophysiology involved in these diseases. New information about more effective regimens with fewer side effects has also been obtained, presenting new treatment options. Clinical manifestations and management of these disorders will be described as well as histopathologic, ultrastructural, and immunopathologic studies that distinguish each disorder and facilitate diagnosis and treatment.

Myofibroblasts in phenytoin-induced hyperplastic connective tissue in the rat and in human gingival overgrowth

Phenytoin is a commonly used anticonvulsant drug for the prevention of seizures. A common side effect of phenytoin (PHT) therapy is connective tissue hyperplasia, particularly in the oral cavity manifesting as gingival overgrowth. Our previous studies concerning the molecular mechanisms of drug-induced gingival overgrowth have demonstrated that PHT alters the normal tissue turnover/wound healing signal by causing changes in macrophage phenotype, resulting in the upregulation of essential polypeptide growth factors such as platelet-derived growth factor (PDGF). The cellular consequences of this elevation in growth factor have not been investigated. The present light and electron microscopic study of rat hyperplastic connective tissue and human gingival overgrowth induced by PHT treatment revealed the presence of numerous myofibroblasts. Cells identified as myofibroblasts were evident in all PHT-treated tissue samples and were characterized by an elongated fusiform cell shape, abundant cytoplasmic rough endoplasmic reticulum/polyribosomes, and accumulations of sub-plasmalemmal microfilaments containing spindle densities. These cells were never observed in control tissues. Myofibroblasts are associated with the later stages of tissue turnover, specifically with the transition from the granulation to the remodeling phases of the wound healing process. The presence of myofibroblasts in hyperplastic connective and gingival tissues induced by PHT treatment suggests that PHT exacerbates the normal tissue turnover/wound healing signals responsible for the appearance of myofibroblasts.

Positive correlation between blood cyclosporin A level and severity of gingival overgrowth in rats

Cyclosporin a is a drug used to control rejection of organ transplantation and autoimmune diseases; however, it has also been implicated in gingival overgrowth. The present study investigates the relationship between severity of gingival overgrowth and blood cyclosporin A (CsA) levels in Fischer rats treated orally with CsA. Thirty-six 15-day-old male rats were divided into six experimental groups and given powdered rat chow containing 0, 50, 100, 200, 300, and 400 micrograms CsA/g diet ad libitum for 40 days. At the end of the 40-day treatment period, whole blood samples were collected from each rat for assessment of CsA levels. The rats were then sacrificed and the gingival sulcus depth (pseudopocket) around mandibular molars measured to estimate gingival overgrowth. The blood levels of CsA in rats increased with increasing amounts of CsA provided in their food. A 100% incidence in gingival overgrowth was induced in all the rats treated orally with CsA. The overgrowth was more severe in buccal than in lingual gingiva. A significantly positive correlation was found between gingival sulcus depth and the blood CsA level (rs = 0.914, P < 0.0001; Spearman's correlation coefficient by rank). On histological examination, the overgrown gingiva consisted of a thickened epithelial layer and an accumulation of subepithelial fibrous connective tissue components without marked distortion of their proportion.

Myasthenia gravis: dental treatment considerations

Myasthenia gravis is an autoimmune neuromuscular disorder that presents challenges for the dental practitioner. Facial and masticatory muscles may be involved and complicate dental treatment. Exacerbations of the skeletal muscle weakness and fatigability that characterize this disorder can be precipitated by certain medications used in dentistry. A review of 47 dental treatment episodes in 16 patients with myasthenia gravis was undertaken to identify neuromuscular responses to dental treatment and post-dental treatment medical therapy required for control of resultant exacerbations of muscular weakness. Neuromuscular sequelae occurred in 5 treatment episodes for four different patients. Management considerations and drug precautions are discussed.

Combined treatment approach to gingival overgrowth due to drug therapy

A case of severe gingival overgrowth associated with combined drug therapy of cyclosporin A and nifedipine is reported. The frequently increased vascularity of the gingival tissues in such cases often causes problems with bleeding both during and after surgery. Acrylic suckdown splints have been used postoperatively to assist haemostasis; however, these can interfere with function and cause discomfort. This report describes a combined treatment approach using conventional gingivectomy and carbon dioxide laser for the removal of the hypertrophic soft tissue. The benefits of such combined treatment include reduced bleeding during surgery with consequent reduced operating time and rapid post-operative haemostasis, thus eliminating the need for a splint.

Histopathologic alterations of periodontium in cyclosporin-treated rats. Is the periodontium a target tissue for the drug?

Gingival dimensions and histopathologic alterations in periodontium were examined in rats continuously exposed to cyclosporin-A (CSA). 60 male Sprague-Dawley rats were divided into 2 groups. Rats in the test group daily received CSA in mineral oil by gastric feeding at a dosage of 30 mg/kg body weight for 6 weeks. Rats in the control group received mineral oil only. 10 rats from each group were sacrificed at 2-week intervals. Gingival dimensions were assessed from stone models obtained from the maxillary and mandibular incisal regions. Horizontal, sagittal and frontal tissue sections were obtained from these regions as well. Gingival dimensions in the mandibular and maxillary incisal regions were significantly increased in rats exposed to CSA. Light-microscopic observations revealed a granulation tissue formation at tooth-gingiva interface and an irregular bony surface on dental alveoli in experimental animals. Because both soft and hard tissue of periodontium in experimental rats being significantly effected by CSA compared to control animals, we hypothesized that the periodontium is a target tissue for CSA.

Pathogenesis of drug-induced gingival overgrowth. A review of studies in the rat model

Drug-induced gingival overgrowth is a side effect associated principally with 3 types of drugs: anticonvulsant (phenytoin), immunosuppressant (cyclosporine A), and various calcium channel blockers (nifedipine, verapamil, diltiazem). In this review, we describe the features of phenytoin-, cyclosporine A- and nifedipine-induced gingival overgrowth in rats and discuss factors influencing the onset and severity of these disorders. There are several features common to the gingival overgrowth induced by these drugs: 1) gingival overgrowth is more conspicuous in the buccal than in the lingual gingiva and less severe in the maxilla than in the mandible; 2) once the blood concentration of the drug reaches a certain level as a result of increasing the dose, the incidence of gingival overgrowth is 100% and its severity is dependent on the blood level, the most severe overgrowth being induced by cyclosporine A; 3) the duration of drug administration for maximal gingival overgrowth to develop is about 40 days; 4) the gingival overgrowth regresses spontaneously after discontinuing the drug; 5) accumulation of dental plaque is not essential for the onset of overgrowth, but plays a role in its severity; and 6) more severe overgrowth is induced in young than in old rats. Furthermore, male rats are more susceptible than females to nifedipine-induced gingival overgrowth. These results suggest that drug-induced gingival overgrowth in rats is dependent on the oral drug dose, blood drug level, age, and sex and that preexisting gingival inflammation is a factor relevant to its severity. Since these factors have also been suggested to be important determinants for human drug-induced gingival overgrowth, the rat model may prove valuable in the future for elucidating the molecular pathogenesis of the disorder.