Anti-resorptive therapy and MRONJ. A survey of the Italian Society of Periodontology and Implantology.

OBJECTIVES: Anti-resorptive agents have been linked to the development of MRONJ in patients undergoing dental surgical procedures. This survey aims to explore the level of knowledge and experience of Italian Society of Periodontology and Implantology members in the management of patients treated with anti-resorptive agents and with the risk of developing MRONJ. MATERIALS AND METHODS: An 18-item questionnaire was submitted by e-mail to the SIdP members. Statistical analyses were carried out. Continuous variables were described as mean ± standard deviation (SD) or median, and first and third quartile according to distribution's normality. Normality of data was checked with Shapiro-Wilk test. RESULTS: Four hundred and fifty-one questionnaires were returned by e-mail (32%). Most of the respondents were private practitioners (81.8%). Only 47.7% declared to be highly confident in managing patients on anti-resorptive therapy while 92.5% reported to have performed tooth extractions and 52.3% implant surgery in patients under anti-resorptive therapy for osteometabolic disorders. One or more MRONJ-affected patients were encountered by 63.2% of the respondents. CONCLUSIONS: This survey highlights the need to develop a "dedicated" program both for dentists and prescribers to improve the level of cooperation and to increase the level of awareness of patients treated with anti-resorptive agents.

Anti-resorptive therapy in the osteometabolic patient affected by periodontitis. A joint position paper of the Italian Society of Orthopaedics and Traumatology (SIOT) and the Italian Society of Periodontology and Implantology (SIdP).

This joint report from the Italian Society of Orthopaedics and Traumatology (SIOT) and the Italian Society of Periodontology and Implantology (SIdP) aims for a consensus around the scientific rationale and clinical strategy for the management of osteoporotic patients affected by periodontitis who are undergoing anti-resorptive (AR) therapy to manage the risk of the occurrence of a medication-related osteonecrosis of the jaws (MRONJ). Osteoporosis and periodontitis are chronic diseases with a high prevalence in aging patients, and they share some of the same pathogenetic mechanisms based upon inflammation. Available evidence shows the relationship among osteoporosis, AR agents, periodontitis and implant therapy in relation to the incidence of MRONJ. Uncontrolled periodontitis may lead to tooth loss and to the need to replace teeth with dental implants. Tooth extraction and surgical dental procedures are recognized as the main risk factors for developing MRONJ in individuals taking AR therapy for osteometabolic conditions. Although the incidence of MRONJ in osteometabolic patients taking AR therapy may be as low as 0.9%, the increasing prevalence of osteoporosis and the high prevalence of periodontitis suggest that this potential complication should not be overlooked. Good clinical practice (GCP) guidelines are proposed that aim at a more integrated approach (prescriber, dentist, periodontist and dental hygienist) in the management of periodontitis patients undergoing AR therapy for osteometabolic disorders to reduce the risk of MRONJ. Dental professional and prescribers should educate patients regarding the potential risk associated with the long-term use of AR therapy and oral health behavior.

Alendronate impairs epithelial adhesion, differentiation and proliferation in human oral mucosa.

OBJECTIVE: This study aimed at evaluating from a morphological point of view the effects of alendronate (ALN), a widely used nitrogen-containing bisphosphonate for the chronic treatment of osteoporosis, on the oral epithelium of healthy keratinized human oral mucosa. Bisphosphonate-related osteonecrosis of the jaw is a well-known severe consequence, but the effects during chronic therapy on the oral soft tissues are still matter of debate. MATERIALS AND METHODS: Six women over 60 year-old undergoing treatment of osteoporosis with 70 mg per week of oral ALN (lasting at least 2 years) were recruited and compared with a gender and age-matched group (n = 6). Proliferation, apoptosis, intercellular adhesion and terminal differentiation (TD) were investigated by immunofluorescence. In parallel, ultrastructural analysis was carried out. RESULTS: By immunofluorescence, a statistically significant decrease in keratinocyte proliferation was detected in the oral epithelium of the ALN group without any sign of apoptosis, but accompanied by a reduction in desmoglein 1 and keratin 10 expressions. In the uppermost layers of the oral epithelium of the ALN group, thin desmosomes were visible by transmission electron microscopy. CONCLUSION: Our results show that epithelial adhesion, TD and proliferation are affected by ALN therapeutic doses in clinically healthy human oral mucosa.

Chlorhexidine (CHX) in dentistry: state of the art.

Chlorhexidine (CHX) is one of the most commonly prescribed antiseptic agents in the dental field. It has a long-lasting antibacterial activity with a broad-spectrum of action and it has been shown to reduce plaque, gingival inflammation and bleeding. Its use is considered a powerful adjuvant to mechanical oral hygiene (brushing and flossing), especially in those cases in which it cannot be performed correctly. Available as mouthwash, gel, aerosol, spray and disks, CHX is considered a safe compound, with minimal and transitory local and systemic side effects. Data support its periodic use as an adjuvant to normal brushing and flossing in subjects unable to maintain proper oral hygiene due to physical and/or mental impairment, or lack of motivation, or decreased salivary rate. CHX is also a useful alternative to mechanical oral hygiene procedures in those cases in which they are contraindicated, e.g. after a surgical procedure, or as a preoperative rinse before procedures in which use of a dental dam is not possible. The aim of this article is to offer a complete review of literature regarding the characteristics, the applications and the problems associated with the use of chlorhexidine in the dental field.

Screening for the undiagnosed diabetes at dental chair-side of an Italian university clinic. A pilot prospective study.

AIM: In Italy there is about one undiagnosed case of diabetes for each known case. The dental office might represent an important setting for screening the glycemic status of patients. The aim of the present study was to evaluate the effectiveness of dental chair-side capillary blood sampling for the identification of undiagnosed hyperglycemia in a group of Italian patients. METHODS: Five hundred fifteen patients >45 years old consecutively visiting a public university dental clinic, where admission is regulated by medical or income criteria, were considered for the study. Demographic data, medical history, time of the last caloric intake and waist width were recorded for each participant. All participants underwent an oral examination. Glycemic values were obtained by capillary blood glucose testing. RESULTS: Of the 400 subjects who took part in the study, a low percentage of unaware diabetic individuals (1.7%) was identified. Inclusion criteria restriction to subjects between 50 and 75 years of age and a waist circumference >92 cm would have resulted in a proportion of diabetic patients of 4.3%. CONCLUSION: Dental chair-side in a public university clinic in Italy failed to disclose the expected number of unaware diabetic patients.

A survey on the experience with dental tourism in a sample of Italian patients.

AIM: Dentistry in Italy is mainly private and therefore perceived as forcedly expensive. Dental tourism is becoming popular in order to get cheap dental care. The aim of this study was to carry out a survey aimed at investigating the perception of dental tourism by Italian patients who have recently received such dental care abroad. METHODS: A questionnaire was posted on the web site of an Italian consumers association (Altroconsumo) and members were invited to fill in the questionnaire in case they had experienced dental treatment abroad. RESULTS: Eighty-one complete forms were included in the study. The main motivation for turning to dental tourism was saving money. Another frequent reason for choosing dental tourism was that full rehabilitation was offered in a short time span, usually one week. Patients have often underlined that they appreciated different aspects of the foreign dentists, like speed, kindness, humanity, interest in the course of the treatment, the feeling of ease conveyed by the environment and the personnel. Past negative experiences with Italian dentists were in some cases advocated as reasons for searching dental care abroad. Such negative experiences resulted in a lack of trust in Italian dentists. Some patients reported that while the overall treatment abroad was carried out in a short time, single prosthetic sessions were very long, up to 6 hours. CONCLUSIONS: Most patients were satisfied with dental tourism.

Detection of survivin mRNA in healthy oral mucosa, oral leucoplakia and oral cancer.

BACKGROUND: Survivin is involved in modulation of cell death and cell division processes. Survivin expression in normal adult tissues has not been fully understood, although it is markedly lower than in cancer, where it is over-expressed. OBJECTIVE: To investigate survivin expression in normal, potentially malignant and cancerous oral mucosa. METHODS: We measured survivin mRNA levels by real-time RT-PCR in specimens of oral mucosa (15 from normal mucosa, 17 from potentially malignant lesions, 17 from neoplasms). Scores were compared using Kruskal-Wallis test and post hoc according to Conover. Chi-squared test was used for dichotomous data. RESULTS: The median relative levels of survivin mRNA resulted six for normal mucosa, eight for potentially malignant lesions, 13 for cancers: differences among these three groups were statistically significant, as between cancer and potentially malignant lesions. Expression in normal mucosa and potentially lesions group showed no significant difference. Low, but not marginal expression of survivin in normal mucosa is a new finding, and it could be explained with the higher sensibility of our methods. CONCLUSIONS: Survivin expression in oral potentially malignant lesions might indicate a progressive deregulation of expression paralleling oncogenesis, particularly during the first stages of process, suggesting a putative predictive role for survivin.

Clinical aspect and survival rates in subject with oral cancer: a retrospective cohort study.

AIM: The aim of this study was to describe and evaluate survival in a group of patients with oral malignant neoplasias, observed at the Unit of Oral Pathology and Medicine, University of Milan, between February 1995 and September 2005. METHODS: This retrospective study considered the clinical histories and anamnestic profiles of a group of 108 patients with malignant oral neoplasms. A sample of 72 out of these 108 patients was identified, for whom follow-up data were available for at least 4 months from the date of diagnosis. Survival times for this group were then evaluated. RESULTS: In this group of 108 patients, 103 were affected by squamous cell carcinoma. The ratio of male to female patients was 1.1:1.0 and the average age at the time of diagnosis was 64.9 years. In 44 out of 91 cases, the site affected was the tongue and in 28 out of 45 cases, the lesion was at an early stage (TNM 1 and 2) at the time of diagnosis. Survival in the group of 72 considered was 84% at 2 years from diagnosis and 55% at 5 years. Diagnosis before the age of 65 favoured a positive prognosis (P=0.01), as did lesions diagnosed at TNM 1 stage, though this was not statistically significant (P=0.1). CONCLUSION: The data provided in this retrospective study were consistent with previous reports of survival rates at 5 years from diagnosis and the improved prognosis for patients diagnosed before the age of 65. The only finding that was different from previous studies was the gender distribution, which in this study was almost equal.

Oral biopsy. A prospective study on 286 consecutive procedures.

AIM: The aim of the present study was to survey oral biopsy procedures, with particular regard to the incidence of adverse events, patients experience and adequacy of the sample. METHODS: This prospective survey was conducted by collecting detailed information from consecutive patients undergoing oral biopsy; data were obtained on the same day of oral biopsy and after 7 days. RESULTS: Data on 286 procedures were collected. About half of the patients had a relevant medical history and were taking one or more medications. During biopsy, the majority of patients (83%) felt no pain, the others reported mild discomfort. Intraoperative adverse events occurred occasionally (4.5%) and were always easily resolved; 18% patients admitted taking painkillers in the days following surgery. The pathologist was always able to make histological diagnosis, although some samples did not include healthy mucosa (32%) or connective tissue (11%). CONCLUSION: Oral biopsy is a safe and well accepted surgical procedure.

Interventions for treating oral leukoplakia.

BACKGROUND: Oral leukoplakia is a relatively common oral lesion that in a small but significant proportion of cases changes into cancer. Since most leukoplakias are asymptomatic, the primary objective of treatment should be to prevent such malignant transformation. OBJECTIVES: To assess effectiveness, safety and acceptability of treatments for leukoplakia. SEARCH STRATEGY: The following databases were searched for relevant trials: Cochrane Oral Health Group's Trials Register (to April 2006), CENTRAL (TheCochrane Library 2006, Issue 1), MEDLINE (from 1966 to December 2005), and EMBASE (from 1980 to December 2005). Handsearching was performed for the main oral medicine journals. References of included studies and reviews were checked. Oral medicine experts were contacted through an European mailing list (EURORALMED). SELECTION CRITERIA: Randomised controlled trials (RCTs), enrolling patients with a diagnosis of oral leukoplakia, were included. Any surgical or medical (topical and systemic) treatment was included. The primary outcome considered was malignant transformation of leukoplakia. Other outcomes considered were clinical resolution, histological modification and frequency of adverse effects. DATA COLLECTION AND ANALYSIS: Data were collected using a specific extraction form. Malignant transformation of leukoplakia, demonstrated by histopathological examination, was the main outcome considered. Secondary outcomes included clinical resolution of the lesion and variation in dysplasia severity. The validity of included studies was assessed by two review authors, on the basis of the method of allocation concealment, blindness of the study and loss of participants. Data were analysed by calculating risk ratio. When valid and relevant data were collected, a meta-analysis of the data was undertaken. MAIN RESULTS: The possible effectiveness of surgical interventions, including laser therapy and cryotherapy, has never been studied by means of a RCT with a no treatment/placebo arm. Twenty-five eligible RCTs of non-surgical interventions were identified: 11 were excluded for different reasons, five were ongoing studies, leaving nine studies to be included in the review (501 patients). Two studies resulted at low risk of bias, six at moderate risk of bias and one at high risk of bias. Vitamin A and retinoids were tested by five RCTs, two studies investigated beta carotene or carotenoids, the other drugs tested were bleomycin (one study), mixed tea (one study) and ketorolac (one study). One study tested two treatments. Malignant transformation was recorded in just two studies: none of the treatments tested showed a benefit when compared with the placebo. Treatment with beta carotene, lycopene and vitamin A or retinoids, was associated with significant rates of clinical resolution, compared with placebo or absence of treatment. Whenever reported, a high rate of relapse was a common finding. Side effects of variable severity were often described; however, interventions were well accepted by patients, since drop-out rates were similar between treatment and control groups. AUTHORS' CONCLUSIONS: To date there is no evidence of effective treatment in preventing malignant transformation of leukoplakia. Treatments may be effective in the resolution of lesion, however relapses and adverse effects are common.

Transdermal fentanyl in HSCT patients: an open trial using transdermal fentanyl for the treatment of oral mucositis pain.

Fentanyl is a synthetic opioid that can be delivered through a transdermal therapeutic system (TTS). The aim of this study was to assess the efficacy of fentanyl TTS in treating oral mucositis pain in 75 adult hematopoietic stem cell transplant (HSCT) patients. The analysis was based on 62 patients who developed mucositis. Pain control was assessed by the patients using a visual analogue scale (VAS) from day 0 to day +33 after HSCT. Fentanyl TTS was administered at the patient's request. In all, 20 patients did not require fentanyl (group A). The first 22 patients asking for the patch received fentanyl 25 microg/h (group B) and the subsequent 20 patients received 50 microg/h (group C). There were no significant differences in pain relief between groups B and C. The expected effect of a decrease in mean pain score (mean of the VAS scores of all of the patients in the same group each day) following the application of fentanyl TTS was not noted. We can conclude that fentanyl TTS at the doses used in this study may not adequately relieve oral mucositis pain.

Dermochondrocorneal dystrophy (François' syndrome). Report of a case.

Dermochondrocorneal dystrophy (François' syndrome) is an extremely rare disorder characterized by firm, nodular lesions involving the hands and the face; osteochondrodystrophy of the peripheral extremital bones, resulting in limitation of movement; and corneal dystrophy marked by white or brownish opacities. A nonfamilial case of dermochondrocorneal dystrophy was studied in a 45-year-old woman who had severe involvement of the gingival and palatal mucous membranes.

Attitude towards smoking and oral cancer prevention among northern Italian dentists.

The aim of the study was to evaluate the smoking habits of Northern Italian dental practitioners and their basic skills in the prevention of oral cancer. 217 of the 250 dental practitioners (86.8%) contacted by telephone from September to December 1994, answered a simple questionnaire. One third of the sample interviewed was formed by current smokers; nevertheless 60.8% of them always advise their patients to give up smoking. Only a relatively small percentage of the questioned dental practitioners (10.6%) do not examine the oral mucosa of the patients on a regular basis and 40% of responders had made a clinical diagnosis of oral cancer in the past. The lack of a specific dental education was associated with less scrupulous examination of the oral soft tissues and minor experience of cancer diagnosis. Despite their smoking habit, Northern Italian dental practitioners self-reported encouraging behaviour towards primary and secondary oral cancer prevention.

Local antimicrobial therapy of oral mucositis in paediatric patients undergoing bone marrow transplantation.

The present investigation has examined the clinical benefits of tobramycin, polymyxin E and amphotericin therapy in the management of oral mucositis in children undergoing chemotherapy prior to bone marrow transplantation. Tobramycin, polymyxin E, and amphotericin reduced the degree of oral mucositis more than conventional therapy of diphenhydramine, Maalox, and local analgesic. While there was a statistically significant fall in the severity of the mucositis with tobramycin, polymyxin E and amphotericin, this was unlikely to be of practical benefit.

Interventions for treating oral leukoplakia.

BACKGROUND: Oral leukoplakia is a relatively common oral lesion that in a small but significant proportion of cases changes into cancer. Since most leukoplakias are asymptomatic, the primary objective of treatment should be to prevent such malignant transformation. OBJECTIVES: To assess effectiveness, safety and acceptability of treatments for leukoplakia. SEARCH STRATEGY: The following databases were searched for relevant trials: Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE, EMBASE. Handsearching was performed for the main oral medicine journals. References of included studies and reviews were checked. Oral medicine experts were contacted through an European mailing list (EURORALMED). SELECTION CRITERIA: Randomised controlled trials (RCTs), enrolling patients with a diagnosis of oral leukoplakia, were included. Any surgical or medical (topical and systemic) treatment was included. The primary outcome considered was malignant transformation of leukoplakia. Other outcomes considered were clinical resolution, histological modification and frequency of adverse effects. DATA COLLECTION AND ANALYSIS: Data were collected using a specific extraction form. Malignant transformation of leukoplakia, demonstrated by histopathological examination, was the main outcome considered. Secondary outcomes included clinical resolution of the lesion and variation in dysplasia severity. The validity of included studies was assessed by two reviewers, on the basis of the method of allocation concealment, blindness of the study and loss of participants. Data were analysed by calculating relative risk. When valid and relevant data were collected, a meta-analysis of the data was undertaken. MAIN RESULTS: The possible effectiveness of surgical interventions, including laser therapy and cryotherapy, has never been studied by means of a RCT. Nineteen potentially eligible RCTs of non-surgical interventions were identified: eight were excluded for different reasons, four were ongoing studies, leaving seven studies to be included in the review. Two studies resulted at low risk of bias, four at moderate risk of bias and one at high risk of bias. Vitamin A and retinoids were tested by five RCTs (245 patients), the other drugs tested were bleomycin (one study), mixed tea (one study) and beta carotene (one study). Malignant transformation was recorded in just two studies: none of the treatments tested showed a benefit when compared with the placebo. Treatment with beta carotene and vitamin A or retinoids, was associated with significant rates of clinical resolution, compared with placebo or absence of treatment. Whenever reported, a high rate of relapse was a common finding. Side effects of variable severity were often described; however, interventions were well accepted by patients, since drop-out rates were similar between treatment and control groups. REVIEWERS' CONCLUSIONS: To date there is no evidence of effective treatment in preventing malignant transformation of leukoplakia. Treatments may be effective in the resolution of lesion, however relapses and adverse effects are common.

Interventions for treating oral leukoplakia.

BACKGROUND: Oral leukoplakia is a relatively common oral lesion that in a varying proportion of cases undergoes malignant transformation. Since most leukoplakias are asymptomatic, the need for treatment is primarily based on the precancerous nature of the lesion. OBJECTIVES: To assess effectiveness, safety and acceptability of treatments for leukoplakia. SEARCH STRATEGY: The following data bases were searched for relevant trials: MEDLINE, EMBASE, CancerLit, Biological Abstracts, Cochrane library. Hand searching was performed for the main oral medicine journals. Oral medicine experts were contacted through an European mailing list (EURORALMED). SELECTION CRITERIA: Randomised controlled trials (RCTs), enrolling patients with a diagnosis of oral leukoplakia, were included. DATA COLLECTION AND ANALYSIS: Data were collected using a specific abstraction form. Malignant transformation of leukoplakia, demonstrated by histopathological examination, was the main outcome considered. Secondary outcomes included clinical resolution of the lesion and variation in dysplasia severity. The validity of included studies was assessed on the basis of the method of allocation concealment, blindness of the study and loss of participants. Data were analysed by calculating relative risk. MAIN RESULTS: The possible effectiveness of surgical interventions, including laser therapy and cryotherapy, has apparently never been studied by means of a RCT. Fourteen potentially eligible RCTs of nonsurgical intervention were identified: five were excluded for different reasons, three were ongoing studies, leaving six studies to be included in the review. Vitamin A and retinoids were tested by four RCTs (224 patients), the other drugs tested were bleomycin (one study), mixed tea (one study) and beta carotene (one study). Malignant transformation was recorded in just two studies: none of the treatments tested showed a benefit when compared with the placebo. Treatment with beta carotene and vitamin A or retinoids, was associated with better rates of clinical remission, compared with placebo or absence of treatment. Whenever reported, a high rate of relapse was a common finding. Side effects of variable severity were often described; however, interventions were well accepted by patients, since drop-out rates were similar between treatment and control groups. REVIEWER'S CONCLUSIONS: To date there is no evidence of effective treatment in preventing malignant transformation of leukoplakia. Treatments may be effective in the resolution of lesion, however relapses and adverse effects are common.

Periodontitis in a patient with chronic neutropenia.

The aim of this investigation was to obtain information about the composition and the morphology of the microorganisms that inhabit the root surface of a patient with chronic neutropenia and severe and progressive periodontitis. In addition, gingival biopsies were studied by both scanning and transmission electron microscopy (SEM and TEM) to look for bacteria within the gingiva. Dark field microscopy (DFM) revealed 50% spirochetes, 30% motile rods, and 20% coccoid forms. Fourteen extracted teeth studied by SEM showed that the distribution of different bacterial morphotypes varies along the root surface and spirochetes are the prevailing bacteria on the most apically located plaque. TEM analyses of gingival tissue revealed no bacterial invasion within the gingiva. This study suggests that spirochetes may play an important role in the etiology of periodontitis associated with chronic neutropenia. In spite of neutropenic status, there was no bacterial invasion into the gingiva, suggesting that host reaction to dental plaque has not been abolished in this condition.

Identification of Actinobacillus actinomycetemcomitans by gold immunolabeling and scanning electron microscopy.

Recent evidence suggests that dental plaque is not a homogeneous bacterial mass but, on the contrary, specific bacterial morphotypes and species may be preferentially located within certain microenvironments. The aim of the present study was to develop combined gold immunolabeling and scanning electron microscopic (SEM) techniques for the identification of periodontal pathogens in subgingival dental plaque and on the root surfaces of extracted teeth. Suspensions of pure A. actinomycetemcomitans cultures or suspensions of A. actinomycetemcomitans mixed together with other oral bacteria were prepared, labeled with goat anti-rabbit IgG conjugated with 5 nm or 40 nm colloidal gold particles, and observed by SEM using both secondary and back-scattered imaging. Scanning electron microscopy demonstrated that the A. actinomycetemcomitans bacterial cell surface was specifically labelled. There was no cross-reaction with any of the other bacterial morphotypes. Only the labeled A. actinomycetemcomitans were visible in mixtures examined by back-scattered imaging scanning electron microscopy. The combined techniques of gold immunolabeling and SEM may, therefore, be useful in identifying A. actinomycetemcomitans in subgingival plaque samples and on the root surfaces of extracted teeth as well as in studies of bacterial ecology in dental plaque, in general.

The effect of surface roughness on early in vivo plaque colonization on titanium.

THE STUDY ASSESSES IN VIVO the surface roughness necessary to reduce plaque colonization on titanium after 24 hours. Three groups of 16 titanium disks were assigned to 3 different polishing groups (A, B, and C). The roughness was evaluated with a laser profilometer and the morphology with a scanning electron microscope (SEM). Eight volunteers were enrolled and two stents were applied in the mandibular posterior region of each. Each stent supported 3 disks, one per group. The volunteers suspended oral hygiene for 24 hours, after which the stents were removed; one was processed for evaluation of the adherent biomass and the other for SEM study. On each specimen a global area of 100 x 125 microns was examined with SEM. The area was composed of five 20 x 25 microns randomly selected fields. For each field the density of bacteria and the morphotypes were recorded. The data quoted for the global area are cumulative of those observed in the 20 x 25 microns fields. Group A had a significantly smoother surface than groups B and C. The adherent microbial biomass determination and SEM evaluation revealed that group A contained less bacteria than the roughest group. The bacterial population was composed of cocci in group A, and of cocci and short and long rods in groups B and C. We conclude that a titanium surface with Ra < or = 0.088 microns and Rz < or = 1.027 microns strongly inhibits accumulation and maturation of plaque at the 24-hour time period and that such smoothness can be achieved in transgingival and healing implant components.

A new method of bacterial identification using gold immunolabelling and scanning electron microscopy.

This study sought to develop an immunolabelling technique to identify specific bacteria by scanning electron microscopy. Bacterial suspensions were prepared of Actinobacillus actinomycetemcomitans, Porphyromonas (Bacteroides) gingivalis and mixtures of these species with other genera of common oral microorganisms. This method was also used to examine subgingival plaques from 6 subjects with chronic adult periodontitis. Sample preparation consisted of prefixation of the bacterial suspensions with 0.2% glutaraldehyde, incubation with species-specific rabbit antisera and goat anti-rabbit IgG conjugated with colloidal gold particles, postfixation in 2% glutaraldehyde and dehydration in ethanol. Finally, the samples were dried, coated with evaporated carbon and examined by scanning electron microscopy. Pure cultures and artificial mixtures of A. actinomycetemcomitans and Bact. gingivalis were specifically labelled by gold probes as demonstrated by both secondary and back-scattered imaging. These species were also evident in samples of subgingival plaque. The findings indicate that this new technique can be used to identify specific microorganisms both in plaque samples and on the root surface of extracted teeth.