Effect of a novel ceramic filling material on plaque formation and marginal gingiva

The aim of this clinical investigation was to evaluate a novel ceramic (CF) filling material (DoxaDent) compared to resin composite (RC) and enamel in regard to plaque formation and gingival inflammation. The CF material is inorganic, non-metallic, and contains calcium aluminate, silicate, and water. To make intra-individual comparisons possible, each participant had at least one set of three test surfaces: two Class V restorations with subgingival cervical margins (one of the novel CF material and one of a hybrid RC) and one non-filled enamel surface (E). The amounts of plaque, gingival crevicular fluid, and clinical signs of gingival inflammation were intra-individually compared in 20 sets of the three test surfaces. In a cross-sectional study (CSS), the effect of oral hygiene on plaque formation and gingivitis around the surfaces was evaluated. In a following 10-day experimental gingivitis study (EGS), plaque formation and the induction of gingivitis during refrain from oral hygiene was compared. In the CSS, no significant differences were found between the surfaces in terms of amount of plaque and degree of gingival inflammation. At the end of the EGS the restorative materials showed a significantly higher amount of plaque (CF versus E, P = 0.014; RC versus E, P = 0.034), but no significant differences were found in degree of gingival inflammation. In condusion, the ceramic filling material was comparable to RC regarding plaque formation and gingival inflammation with customary oral hygiene. With neglected oral hygiene, significantly less plaque growth and a non-significant tendency toward lower amounts of gingival crevicular fluid were observed on enamel surfaces.     

Dental biofilm, gingivitis and interleukin-1 adjacent to approximal sites of a bonded ceramic

AIM: The aim of this study was to investigate in vivo the influence of aged, resin-bonded, ceramic restorations on approximal dental biofilm formation and gingival inflammatory response, associated with and without customary oral hygiene. MATERIAL AND METHODS: In a cross-sectional and in a 10-day experimental gingivitis study, Quigley-Hein plaque index, gingival index (GI), crevicular fluid and its levels of interleukin (IL)-1alpha, -1beta and receptor antagonist were measured at appoximal surfaces of leucite-reinforced bonded ceramic coverages, resin composite restorations and enamel and compared intra-individually in 17 participants. RESULTS: No differences were found between the ceramic, composite and enamel regarding plaque index, GI, levels of IL-1alpha, -1beta and the receptor antagonist. Throughout, higher crevicular fluid amounts were observed at ceramic sites compared with the enamel (p<0.05). In the experimental gingivitis, plaque index, GI, crevicular fluid and its IL-1alpha levels increased significantly. CONCLUSION: The need for optimal oral hygiene and professional preventive oral health care does not seem to be reduced with regard to approximal surfaces of aged, resin-bonded, leucite-reinforced ceramic restorations in comparison with those of a hybrid, resin composite and enamel.     

Development of gingivitis around aged restorations of resin-modified glass ionomer cement, polyacid-modified resin composite (compomer) and resin composite

Resin-modified glass ionomer cements (RMGIC) and polyacid-modified resin composites (PMC, compomers) are two recently introduced material groups supposed to replace traditional cements in operative dentistry. The new restoratives release initially fluoride in different relatively high concentrations, which decrease gradually during the first weeks in vivo. Earlier studies showed a stronger subclinical inflammatory reaction around different conventional tooth colored restorative materials than around intact enamel. The aim of this study was to compare intra-individually the initiation of gingival inflammation around, aged RMGIC, PMC and resin composite restorations. Subgingivally located Class III restorations were placed in 17 patients. Each patient received one of each of the experimental materials. All patients were placed on an oral hygiene regime 1-year after finishing of the restorations. Gingivitis was induced during a one-week period without oral hygiene. The gingival condition was assessed by sampling of gingival crevicular fluid (GCF), registration of the amount of bacterial plaque and by registration of bleeding after gentle probing of the entrance of the gingival sulcus (SBI) on the experimental filling- and control-enamel surfaces at days 0 and 7. No differences were seen in plaque and gingival index scores between the materials at both days. The GCF increased significantly for all surfaces during the experimental gingivitis period. At day 7 significantly lower GCF was sampled around the enamel surfaces. In conclusion, the differences between the materials did not result in measurable differences concerning clinical or subclinical signs of gingivitis. Received: 19 September 1998 / Accepted: 26 November 1998     

Effect of localized experimental gingivitis on early supragingival plaque accumulation

Abstract Previous investigations have reported increased plaque formation in the presence of gingival inflammation as compared with gingival health. In these investigations, experimental gingivitis has been induced by total abolition of oral hygiene such that increased levels of salivary bacteria could contribute to the increased plaque formation. In the present study, experimental gingivitis was localized to 2 selected teeth whilst maintaining normal oral hygiene measures in the rest of the mouth. The aim of this study was to investigate whether the mass of plaque accumulating in a 3-day period is influenced by the inflammatory status of the adjacent gingival margins. Following scaling, prophylaxis and a period of optimal hygiene to establish gingival health, “plaque-guards” were worn during routine oral hygiene performance to prevent any cleaning on the buccal surfaces of teeth 14 and 15 from days 0 to 3. On day 3, accumulated plaque was removed from a 1.5 mm zone on the buccal surfaces of 14 and 15 adjacent to the gingival margins and weighed immediately. Subjects continued to wear their plaque-guards during oral hygiene until day 14 to induce experimental gingivitis around the experimental teeth. At day 14, all plaque was cleaned from the buccal surfaces of the experimental teeth and the mass of plaque accumulating over the next 3 days weighed on day 17. Comparison of plaque weights showed that the wet-weight of 3 day-old plaque was higher in the presence of experimental gingivitis than in the presence of gingival health (p= 0.02). This observation suggests that the inflammatory status of the marginal gingival has an important effect on early, supragingival plaque accumulation.     

The effect of glass ionomer cement and composite resin fillings on marginal gingiva

Abstract Glass ionomer cement and composite resin are the most popular restorative materials in operative dentistry today. Earlier studies have shown more crevicular exudate around different types of composite resins than around intact enamel surfaces. The aim of this study was (1) to investigate plaque, retention on and the condition of the gingiva around, 1-year-old, subgingivally located, glass ionomer cement and composite resin fillings, and (2) to compare the initiation of gingival inflammation around these materials with that around enamel during a 14-day period of experimental gingivitis. Plaque index, gingival index, bleeding on probing and crevicular fluid were recorded and compared intra-individually. The amount of plaque and the degree of gingivitis adjacent to the composite fillings were not significantly higher than those for the glass ionomer cement and enamel surfaces in both the cross sectional and the experimental gingivitis study. Composite resin surfaces showed significantly higher crevicular fluid levels than did enamel at all days in the experimental gingivitis study. Glass ionomer cement showed significantly higher values at day-0 and day-7.     

Chemotactic activity in experimental gingivitis

abstract — Forty-eight dental students were screened regarding the rate of plaque formation. The four most rapid (RPF-group) and the four slowest (SPF-group) plaque formers were selected and compared as to: (1) the development of gingivitis during a 14-day period without oral hygiene, (2) the chemotactic activity elaborated by (a) gingival crevicular material (GCM) sampled 24 h after withdrawal of oral hygiene measures and (b) 4- and 8-day-old plaques, and (3) permeability-inducing factors in 4- and 8-day-old plaques. The Gingival Index, Plaque Index and flow of gingival fluid were used for assessing plaque formation and gingivitis development. The chemotactic activity was estimated with the use of Boyden's in vitro model, and subcutaneously implanted wound chambers were used for demonstrating change in vascular permeability. It was found that: (1) individuals vary considerably with regard to the rate of formation of dental plaque, (2) gingivitis developed faster in the RPF group than in the SPF group, (3) GCM sampled already 24 h after cessation of oral hygiene yielded higher chemotactic activity in the RPF group than in the SPF group, and (4) the RPF and SPF groups did not differ from one another regarding chemotactic activity or permeability-inducing activity of equal amounts (wet weight) of plaque.     

Development of gingivitis around different types of composite resin

Earlier studies have demonstrated signs of gingivitis around conventional composite resin restorations. Newly developed resin types differ considerably in composition and surface characteristics. The purpose of this study was to compare the initiation of gingival inflammation around aged restorations of 3 types of composite resins and around enamel, during a 7-day period of experimental gingivitis. Plaque index, gingival index and crevicular exudate were registered at days 0 and 7. There was significantly less exudate around the intact enamel surfaces than around the composite fillings at both registration times. The plaque and gingival indices showed no significant differences among the composite resins and enamel. The results indicate that differences among the resins with regard to surface roughness and composition did not result in clinically measurable differences in the development of plaque and gingivitis.     

Microbiological profile and calprotectin expression in naturally occurring and experimentally induced gingivitis

Objectives

This study was performed to evaluate the microbiological profile and the calprotectin expression in gingival crevicular fluid (GCF) in spontaneous and experimentally induced gingival inflammation.

Materials and methods

Thirty-seven periodontally healthy subjects were evaluated in real life conditions (N-O gingivitis) as well as after 21?days of experimental gingivitis trial (E-I gingivitis). During the experimental gingivitis trial, in one maxillary quadrant (test quadrant), gingival inflammation was induced by oral hygiene abstention, while in the contralateral (control) quadrant, oral hygiene was routinely continued.

Results

The results of the study showed that (1) the microbiological profile of quadrants where gingival inflammation was experimentally induced (i.e., E-I test quadrants) differed significantly from that of either quadrants where gingival inflammation was controlled by proper plaque control (i.e., E-I control quadrants) or quadrants with N-O gingivitis, and (2) GCF calprotectin was significantly higher at E-I test quadrants compared to either E-I control quadrants or quadrants with N-O gingivitis. A positive intrasubject correlation was found between GCF concentration of calprotectin at sites presenting N-O and E-I gingivitis.

Conclusions

N-O and E-I gingivitis showed a different microbiological profile of the subgingival environment. GCF calprotectin is a reliable marker of gingival inflammation, and its concentration in N-O gingivitis is correlated with its expression in E-I gingivitis.

Clinical relevance

The modality of plaque accumulation seems to affect the subgingival microbiological profile associated with a gingivitis condition. Calprotectin levels in GCF may be regarded as a promising marker of the individual susceptibility to develop gingival inflammation in response to experimentally induced plaque accumulation.     

The effect of different types of composite resin fillings on marginal gingiva

Earlier studies of plaque accumulation on and gingival response around conventional composite resin fillings have produced conflicting results. No studies have been found in which the gingival reaction around newer types of resin fillings had been recorded. The aim of this study was to measure plaque retention and gingival conditions around in vivo, aged, subgingivally located, composite fillings of conventional, hybrid and microfiller types. This study was performed in 2 groups of patients. In the 1st group, there were 108 1-year-old class-III restorations of the 3 composite types and in the 2nd group, 228 3- or 4-year-old class-III or class-IV fillings. Plaque and gingival index scores and the amount of crevicular fluid were recorded. In the group with 1-year-old fillings, the composite resins did not adversely affect the health of the gingival tissues. The amount of plaque on and the degree of gingivitis around the composite fillings were not significantly higher than those for the enamel surfaces. Significant differences in the amount of crevicular fluid were found between both the conventional and hybrid composites and the enamel. In the groups with 3-4 year-old fillings, the indices for each material were significantly higher than those for the enamel surfaces and the fillings showed greater amounts of plaque and a higher degree of gingivitis than the 1-year-old fillings. Differences among the 3 types of composite resins were minimal in both groups and not statistically significant.     

The effects of periodontal therapy on intracrevicular prostaglandin E2 concentrations and clinical parameters in pregnancy

BACKGROUND: The increase in circulating levels of progesterone during pregnancy stimulates production of prostaglandins, especially prostaglandin E2, possibly resulting in pregnancy gingivitis. The purpose of this study is to evaluate the influence of prostaglandin E2 concentrations on gingival tissues in pregnancy and to assess its relationship to clinical parameters. METHODS: This study evaluates the effects of periodontal treatment on clinical indices including plaque index, gingival index, probing depth, and gingival crevicular fluid prostaglandin E2 levels of 22 pregnant women in their first, second, and third trimesters. Initial periodontal therapy consisting of scaling, root planing, and oral hygiene instruction was performed at the beginning of the first trimester and repeated each trimester. Prostaglandin E2 concentrations in gingival crevicular fluid were determined using a commercially available enzyme immunoassay kit. The statistical tests used were paired sample test and correlation analysis. RESULTS: The results of the study show that periodontal therapy has resulted in an improvement in clinical parameters (P<0.05). There is also a statistically significant decrease in levels of prostaglandin E2 at the second and third trimesters following periodontal therapy (P <0.001). The correlation between prostaglandin E2 concentrations and clinical parameters is found to be non-significant (P >0.05). CONCLUSIONS: Our data indicate that levels of prostaglandin E2 in gingival crevicular fluid may be used as a marker of gingival inflammation in order to determine the effects of periodontal therapy in pregnancy. Periodontal therapy that is performed throughout the entire pregnancy period may help prevent the threat of pregnancy gingivitis.     

Experimental gingivitis in man

After 9–21 days without oral hygiene eleven experimental subjects with previously excellent oral hygiene and healthy gingivae developed heavy accumulations of plaque and generalized mild gingivitis. The individual rate of development of gingivitis was closely correlated with the rate of plaque accumulation. Characteristic bacteriological changes were revealed in the plaque along the gingival margin during this experiment. Initially, i.e. when the teeth were clean and the gingiva healthy, the extremely sparse plaque flora consisted almost exclusively of gram-positive cocci and rods. The first phase of plaque development occurred during the first 2 days without oral hygiene and consisted of a proliferation of the gram-positive cocci and rods and an addition of about 30 per cent gram-negative cocci and rods. During the second phase (after 1–4 days) fusobacteria and filaments appeared and increased until they each made up about seven per cent of the flora. During the third phase (after 4–9 days) the flora was supplemented with spirilla and spirochetes, and at the end of the period without oral hygiene each of these two groups of organisms accounted for about two per cent of the plaque flora. In specific areas the gingival condition was correlated with the composition of the plaque and it was found that mild gingivitis could be diagnosed clinically at approximately the same time as the complex flora was established. However, sub-clinical inflammation started much earlier, probably as a reaction to the first phases of plaque development. When oral hygiene was reinstituted, the plaque in most areas disappeared in 1–2 days and after 7–11 days the Plaque Index for each subject was as low as before the experiment. Correspondingly, after 1–2 days most tooth surfaces only harbored the original sparse flora of gram-positive cocci and rods. The gingival inflammation in an area usually disappeared one day after the plaque had been removed.     

Differences in the inflammatory response in young and old human subjects during the course of experimental gingivitis

The aim of the present experiment was to study changes in (i) the composition of the inflammatory cell infiltrates and (ii) levels of alpha 2-macroglobulin, lactoferrin and IgG subclasses in gingival crevicular fluid in young and old individuals during 3 weeks of plaque formation. To establish healthy gingival conditions, all subjects received professional tooth cleaning during a 4 week pre-experimental period. The experimental sites included the mesio-palatal, palatal, and disto-palatal surfaces of all teeth present in the 15...25 tooth region. At baseline (day 0) assessments of plaque and gingivitis, microbial sampling and gingival fluid assessment were performed and one gingival biopsy harvested from each subject. Following the baseline examination, the participants abolished mechanical tooth cleaning measures in the palatal and approximal surfaces of 15...25. The clinical examination and the gingival fluid measurement were repeated on days 7, 14 and 21 of no oral hygiene. The microbiological sampling and the biopsy procedure were repeated on days 7 and 21. The gingival crevicular fluid samples harvested from the old individuals had higher levels of alpha 2-macroglobulin and IgG3 compared to young subjects. The immunohistochemical analyses of the biopsies demonstrated that the gingival lesion representing the old individuals harbored a higher proportion of B-cells and a lower density of PMN cells compared to the infiltrate in the young group of subjects. It is suggested that differences exist in the inflammatory response to de novo plaque formation in young and old individuals.     

Identification of inflammatory response patterns in experimental gingivitis studies

We used novel analytical approaches to identify inflammatory response patterns to plaque accumulation in experimental gingivitis studies in humans. Data from two experimental gingivitis studies [Dataset I (n = 40) and Dataset II (n = 42)], which differed in design and recording methods, were used. Both studies comprised a three‐phase program as follows: pre‐induction period (oral hygiene as usual for Dataset I; professional tooth cleaning for Dataset II); induction period (plaque accumulation); and resolution period (oral hygiene as usual). Clinical recordings of plaque and gingival inflammation were made on days 0, 4, 9, and 14 for Dataset I and on days ?14, 0, 7, 21, and 35 for Dataset II. Group‐based‐trajectory and growth curve modeling were used for data analysis. In Dataset I, gingival response to plaque accumulation was found to be lagged in time. Different group‐based response patterns for gingival inflammation were not identified. However, in Dataset II, ‘fast’ and ‘slow’ gingival inflammation responders were identified. ‘Slow’ responders had lagged inflammation responses, whereas ‘fast’ responders seemed to respond immediately to plaque. The findings show that analytical approaches which consider the data structure allow investigation of the dynamics of the relationship between plaque accumulation and gingival inflammation and facilitate the identification of differential patterns of gingival inflammation development.     

Microcirculatory dynamics in experimental human gingivitis

Abstract The purpose of this study was to determine the changes that occur in the gingival microcirculation during the development of experimental gingivitis in humans. There have been no studies published to date combining videomicroscopy and laser Doppler flowmetry to study vascular dynamics in experimental gingivitis. Alterations occurring in the microcirculation of the marginal gingiva in 10 (18–30-year-old), healthy male humans when they suspended oral hygiene procedures in a proscribed area for 12–16 days were monitored. A partial mouth, experimental gingivitis model was employed. Gingival health was evaluated before and after the experimental period by assessing gingival and plaque indices and gingival crevicular fluid volume. Gingival vascular monitoring included measurement of red blood cell velocity in individual gingival microvessels via video-microscopy and measurement of regional gingival blood flow using laser doppler flowmetry. The number of vessels visible in a given microscopic field in a given subject and the number of vessels exhibiting flow were also determined from the videotapes. Systemic cardiovascular and respiratory parameters were monitored to ensure that gingival vascular changes were not secondary to systemic changes. Gingivitis developed in all subjects; significant increases (Student t-test, P < 0.05) were seen in plaque index, gingival index, bleeding on probing and crevicular fluid volume. No change in superficial capillary blood velocity and a significant decrease in gingival regional blood flow were seen with gingivitis. A significant increase in the number of vessels visible in microscopic fields and a decrease in the % of vessels exhibiting flow were observed. Gingival microcirculation exhibited a dramatic, dynamic change in response to the development and progression of gingivitis.     

Periodontal therapy for the ageing mouth.

Epidemiological studies have shown that the prevalence and severity of periodontal disease and tooth loss increase with age. Other studies indicate that gingival recession becomes more prevalent as age progresses. In addition, it has been demonstrated experimentally that elderly individuals develop more rapid and severe gingivitis than young individuals following the abstention of oral hygiene. However, to date no one has established which changes associated with ageing are responsible for these clinical observations. A population of elderly patients (60 years or older) has been evaluated at Northwestern University as to the role of gingival recession and inadequate zones of attached gingiva in the development of dental plaque and gingivitis. The controls for this study consisted of a young population (under 25 years old) with similar gingival defects. In addition, we have found that elderly individuals need more frequent oral prophylaxis for the maintenance of gingival health and to prevent further loss of alveolar bone. This need for more frequent oral prophylaxis is due in large part to the increased incidence of exposed root surface which allows for more rapid plaque accumulation and calculus formation than do enamel surfaces. This and other preliminary evidence suggests that elderly patients with periodontal disease should receive more aggressive therapy than is commonly practised today.     

Enzyme activities in experimental gingivitis in man

abstract – The purpose of the present investigation was to study hyaluronidase, protease, and lysozyme in dental plaque material and gingival fluid during the initial stages of gingivitis. Ten persons with healthy gingiva were subjected to a three-week period without oral hygiene. During this period they developed abundance of plaque and generalized gingivitis. Hyaluronidase activity in dental plaque was highest on day 3 and then decreased during the whole experimental period. Protease and lysozyme activities varied during the experiment. An apparent trend towards higher lysozyme activity of gingival fluid with increased severity of gingival inflammation was noticed. No hyaluronidase and protease activities were detected in the gingival fluid. The hyaluronidases from plaque material of different days were separated by isoelectric focusing into at least two different fractions (pI 5.0 and pI 8.0). Proteolytic fractions were found over a wide pi interval (4.2–6.8) during all days. In all separations one lysozyme peak between pH 9.5–10.0 was found.     

Dental biofilms at healthy and inflamed gingival margins

Objectives: The increased plaque formation observed in gingival inflammation is not fully understood. Receptor proteins in the dental pellicle might influence bacterial adhesion and subsequent plaque formation. The purpose of the present study was to examine proteins and microorganisms in dental biofilms, at healthy and inflamed gingival margins. Material and methods: To see whether marginal inflammation affects the composition of the pellicle and the early dental plaque, samples were taken from the gingival and incisal parts of teeth in periodontally healthy subjects, both in gingival health and during experimental gingivitis. Pellicle proteins were analysed using gel-electrophoresis, immunoblotting and image analysis. Bacteria were analysed by culturing and the PCR technique. Results: During gingivitis, the rate of plaque formation increased significantly. The semiquantitative amounts of proteins and the numbers of bacteria varied considerably between individuals and surfaces. The amount of total and individual pellicle proteins and the total numbers of bacteria were, however, increased during gingivitis and the increase in proteins was statistically significant on the incisal parts of tooth surfaces. Compared to a healthy gingiva, reduced numbers for Actinomyces spp. (incisal parts only) and streptococci and increased numbers of periodontopathogens in the 4 h dental biofilms were seen at the inflamed gingiva. Conclusion: Increased gingival crevicular fluid flow during gingivitis affects pellicle formation and increased plasma proteins in the pellicle may modify bacterial attachment and early dental plaque composition.     

The effect of age on the development of gingivitis

Abstract In the present “experimental gingivitis” study, the response of the marginal gingiva to plaque formation was studied in one group of young subjects, 20-25 years of age, and in one group of older subjects, aged 65-80 years. During a 4-week period, all subjects received a series of professional tooth cleaning to establish healthy gingival conditions. A baseline examination (Day 0) included assessments of plaque and gingivitis. Sites that were examined (the experimental sites) included the mesiopalatal, palatal, and dislopalatal surfaces of all teeth present in the 15. 25 tooth region. Among the experimental sites, microbial sampling and gingival fluid assessment were performed and one gingival biopsy harvested from each subject. Following the baseline examination, the participants abolished mechanical tooth cleaning measures in the palatal and approximal surfaces of 15, 25. The clinical examination and the gingival fluid measurement were repeated on days 7, 14 and 21 of no oral hygiene. The microbiological sampling and the biopsy procedure were repeated on days 7 and 21. The data collected demonstrated that old subjects, during a 3-week period of oral hygiene abstention, formed similar amounts of plaque as the young subjects, but developed more gingivitis than young subjects. Thus, the clinical gingivitis assessments, the gingival fluid measurements and morphometric determinations made in the biopsy samples documented that the gingival lesion which formed in the old individuals was more pronounced and contained more inflammatory cells than the corresponding lesion in the young subject sample.     

Studies of host responses during experimental gingivitis in humans

The aim of the study was to find out whether autologous supragingival plaques collected at various times during the development of experimental gingivitis in men differ in their potential to induce PMN responses in vitro. Ten subjects refrained from all oral hygiene for a period of 21 days. At day 0, Day 3 and Day 21 after cressation of oral hygiene clinical indices (plaque index, gingival index, gingival crevicular fluid flow) were assessed plaque was collected at day 3 and Day 21 after cessation of Oral hygiene clinical indices (plaque index, gingival index, gingival crevicular fluid flow) were assessed plaque was collected at Day 3 and Day 21. PMNs, isolated from peripheral blood 1–2 months after the non-brushing period were incubated with the various autologous plaques in the presence or the absence of autologous serum. Supernatants of cell cultures were monitored for extracellular release of lysosomal constituents, viz. lysozyme, myeloperoxidase and lactoferrin. There was no difference in the amounts of lysozyme, myeloperox dase and lactoferrin. There was no difference in the amounts of lysozyme or myeloperoxidase released by PMNs. The inclusion of fresh serum enhanced PMN release reactions but there was no significant differences in the relative capacity of Day 0, Day3 and Day 21 sera to modulate PMN responses. A statistically significant positive correlation was established betwen the magnitude of lactoferrin release from PMNs exposed to Day 3 plaque and the gingival fluid flow recorded on Day3. Lactoferrin is segregated in the specific granules of the PMNs which also contain other cationic proteins, collagenases and neutral proteinases. These data suggest that a possible causal relationship may exit between the release of PMN constituents and the development of inflammation during the early phases of gingivitis.     

Development of gingivitis in pre-school children and young adults

Earlier studies suggest that children and adults differ in the propensity to develop gingivitis when oral hygiene is abandoned. To confirm the existence of such a difference, a comparative study of pre-school children and young adults was made with objective registration methods. The author performed all registrations. After a period of intensive oral hygiene, all cleaning of teeth was discontinued for 21 days. The amount of bacterial plaque, the amount of gingival exudate and crevicular leukocytes and the bleeding tendency were registered on days 0, 7, 14 and 21. During the experiment the amount of bacterial plaque increased continously in both groups. The amount of gingival exudate and the tendency to gingival bleeding increased to high values in the adults, while only a small rise was seen in the children. The amount of crevicular leukocytes increased in both groups, but the increment was greater in the adults. A comparison concerning differences in gingival exudate and bleeding tendency between pre-school children and adults was undertaken for gingival units that showed a similar plaque development. Under these statistically acceptable prerequisites, it was shown that there is a real difference in the tendency to develop gingivitis between pre-school children and adults.