Microbiology of early supragingival plaque development after delmopinol treatment

Adjunctive effect of mouthrinse on treatment of peri-implant mucositis using mechanical debridement: A randomized clinical trial

Aim

To study effect of delmopinol hydrochloride (DEL) in comparison with chlorhexidine digluconate (CHX) and a placebo (PLA) in addition to non‐surgical mechanical debridement in patients with peri‐implant mucositis.

Materials and methods

Eighty‐nine patients with at least one implant diagnosed with peri‐implant mucositis were randomly assigned to one of three study groups (DEL, CHX and PLA). Professional non‐surgical mechanical debridement was performed at baseline. Mouth rinsing was carried out by the patients twice a day in addition to their regular oral hygiene practices. Assessments of efficacy were performed for the primary outcome ‐ Implant bleeding on probing (IBOP%) and secondary outcomes ‐ modified Bleeding Index (mBI) and modified Plaque Index (mPI) at 1 and 3 months.

Results

At 3 months, there was statistically significant reduction in IBOP% and mBI within the study groups compared to baseline. However, there was no statistically significant difference between the study groups at 3 months follow‐up. Moreover, there was a statistically significant difference according to mPI at 1 month between the chlorhexidine and placebo group (p = .004).

Conclusions

This study confirms that mechanical debridement combined with oral hygiene instruction is effective in treatment of peri‐implant mucositis. The clinical effects between groups were comparable.

Chemical Plaque Control Strategies in the Prevention of Biofilm-associated Oral Diseases

Dental plaque is a biofilm that forms naturally on the surfaces of exposed teeth and other areas of the oral cavity. It is the primary etiological factor for the most frequently occurring oral diseases, such as dental caries and periodontal diseases. Specific, nonspecific, and ecologic plaque hypothesis explains the causation of dental and associated diseases. Adequate control of biofilm accumulation on teeth has been the cornerstone of prevention of periodontitis and dental caries. Mechanical plaque control is the mainstay for prevention of oral diseases, but it requires patient cooperation and motivation; therefore, chemical plaque control agents act as useful adjuvants for achieving the desired results. Hence, it is imperative for the clinicians to update their knowledge in chemical antiplaque agents and other developments for the effective management of plaque biofilm-associated diseases. This article explores the critical analysis of various chemical plaque control strategies and the current trends in the control and prevention of dental plaque biofilm.

Scanning electron microscopy of growing dental plaque: a quantitative study with different mouth rinses

The aim of this study was to quantify the influence of different mouth rinses on dental plaque. Wearing splints with enamel pieces 24 volunteers rinsed with essential oils, amine/stannous fluoride, or chlorhexidine digluconate (0.12%) mouth rinses. After 24, 48, 72, and 96 h the enamel pieces were analyzed by scanning electron microscopy. The counts of cocci and bacilli in different plaque layers and the plaque thickness were almost similar using essential oils and amine/stannous fluoride. These results differed significantly from those of chlorhexidine digluconate mouth rinses. The results for plaque thickness were without significant differences between the groups at any appointment.

Percent of plaque on individual tooth surfaces and differences in plaque area between adjacent teeth in healthy adults

OBJECTIVES

To apply a planimetric method to determine the percentage of the tooth area covered by plaque on individual tooth surfaces and to compare the percentage of plaque between adjacent tooth surfaces.

METHODS

Forty-three adults, mean age 43.0 years, with no signs of periodontal disease, participated. The subjects underwent comprehensive professional cleaning of all teeth. The subjects were then instructed to maintain their ordinary oral hygiene habits. Plaque was registered after 1 month, on each individual tooth surface by use of P%I.

RESULTS

The pattern of plaque accumulation was in large symmetrical, with differences in mean P%I between several adjacent tooth surfaces, e.g. for the maxillary buccal and lingual tooth surfaces between the first and second molars (P<0.001) and for the lingual tooth surfaces between the canines and the first premolars (P<0.01).

CONCLUSION

In the present study, it was possible to identify and describe adjacent tooth surfaces with the most pronounced plaque accumulation, to make further improvements of oral hygiene possible.

Anti-plaque agents in the prevention of biofilm-associated oral diseases

The prevention of dental caries and periodontal diseases is targeted at the control of dental plaque. In this context, chemical agents could represent a valuable complement to mechanical plaque control. The active agents should prevent biofilm formation without affecting the biological equilibrium within the oral cavity. Depending on the goals of the preventive measures, various strategies may be considered. Anti-plaque agents with properties other than bactericidal or bacteriostatic activities may be used in primary prevention. In this approach, a modest antiplaque effect may be sufficient or even desirable, as it would decrease the side effects of the active agent. Antimicrobial agents are best indicated in secondary and tertiary prevention, as the objectives are to restore health and to prevent disease recurrence. The rational is to prevent or delay subgingival recolonization by pathogenic micro-organisms. The development of in vitro oral biofilm models certainly represents a major advance for studying and testing oral anti-plaque agents in recent years. The results of these studies have shown that chlorhexidine, hexetidine, delmopinol, amine fluoride/stannous fluoride, triclosan, phenolic compounds, among others, may inhibit biofilm development and maturation as well as affect bacterial metabolism.

6-month use of 0.2% delmopinol hydrochloride in comparison with 0.2% chlorhexidine digluconate and placebo (II). Effect on plaque and salivary microflora

This double-blind, randomised, 6-month clinical trial with parallel group design in 68 subjects with gingivitis was conducted to study the effects on the oral flora of delmopinol hydrochloride 2 mg/ml (0.2% w/v, Decapinol Mouthwash), when used for partly supervised mouthrinsing in comparison with placebo and chlorhexidine digluconate 2 mg/ml (0.2% w/v, Hibitane Dental, ICI Pharmaceuticals, UK). Apart from estimating the total cultivable microbial dental plaque flora and salivary flora, analyses were focused on bacterial groups associated with gingivitis/periodontitis and dental caries. Furthermore, the presence of staphylococci, gram-negative enteric bacteria and yeasts in saliva were evaluated. The minimal inhibitory concentration (MIC) was determined for isolates belonging to the predominating micro-organisms in samples of both dental plaque and saliva. In relation to the findings in the placebo group, the use of delmopinol during the rinsing period did not produce an undesirable shift in the bacterial populations considered to be related to dental caries or periodontal diseases. These groups remained virtually unchanged during the study. In relation to the observations in the placebo group, slight reductions in the total cultivable plaque and salivary flora were observed during the study and no change was found in the ratio total anaerobically/aerobically cultivable microbial flora. Furthermore, no increased growth in staphylococci, enteric bacteria or yeasts was observed in the saliva samples. The pattern of changes taking place in the composition of the plaque and salivary microbial flora in samples from the participants rinsing with chlorhexidine were in most aspects similar to that observed in the delmopinol group. In the delmopinol group, no microbiologically significant changes were observed over time in the MIC-values for the isolates, neither in the plaque nor in the saliva samples, which indicates that no adaptation to delmopinol had taken place during the rinsing period. Similar observations were made for the plaque isolates in samples from the participants in the chlorhexidine group. On the other hand, when gram-positive and catalase-negative cocci from the saliva samples of the latter group were tested against chlorhexidine, 4-6 times higher MIC-values were obtained at 3 and 6 months both when compared to baseline and in comparison with the other two rinsing groups (p<0.01 or p<0.05). Neither delmopinol nor chlorhexidine showed any residual effect on the studied microbial groups in the plaque and the saliva samples 3 months after the end of treatment. In conclusion, delmopinol was accompanied by a composition of the plaque and salivary flora associated with healthy conditions in the oral cavity.

6-month use of 0.2% delmopinol hydrochloride in comparison with 0.2% chlorhexidine digluconate and placebo. (I). Effect on plaque formation and gingivitis

A double-blind, randomised, 6-month clinical trial with parallel group design in 149 patients with gingivitis was conducted to study the efficacy and safety of delmopinol hydrochloride 2 mg/ml (0.2% w/v, Decapinol Mouthwash) used for partly supervised mouthrinsing in comparison with chlorhexidine digluconate 2 mg/ml (0.2% w/v, Hibitane Dental, ICI Pharmaceuticals, UK) and placebo as an addition to normal oral hygiene. Assessments of efficacy were performed using the plaque index and bleeding on probing (BOP). Delmopinol showed 22% lower plaque index scores than placebo after 3 months (p<0.01) and 13% lower scores after 6 months. The corresponding figures for chlorhexidine were 38% (p<0.001) and 38% (p<0.001) after 3 and 6 months, respectively. Bleeding on probing was reduced for delmopinol in comparison with placebo by 11% after 3 months and by 18% (p<0.05) after 6 months. For chlorhexidine the corresponding figures were 18% (p<0.01) and 22% (p<0.01) after 3 and 6 months, respectively. While chlorhexidine showed greater plaque reduction than delmopinol (p<0.01 at 6 months), no statistically significant difference was reached between these two solutions regarding BOP. Both active solutions showed an increased amount of dental calculus in comparison with placebo. A transient anaesthetic sensation in the oral mucosa and taste affection were commonly reported adverse events in both the delmopinol and the chlorhexidine groups. The number of patients withdrawn from treatment due to adverse events or lack of cooperation was 7 in the chlorhexidine group, 4 in the placebo group and 1 in the delmopinol group. The results showed that rinsing with either 0.2% delmopinol hydrochloride or 0.2% chlorhexidine digluconate twice daily for 60 secs for 6 months results in less plaque formation and gingivitis than rinsing with placebo. Mouthrinsing with the 0.2% delmopinol hydrochloride solution was well accepted in this study.

Plaque formation and gingivitis after supervised mouthrinsing with 0.2% delmopinol hydrochloride, 0.2% chlorhexidine digluconate and placebo for 6 months

OBJECTIVES AND METHODS

A double-blind, randomized, 6-month clinical trial with parallel group design in 162 patients with gingivitis divided into three rinsing groups was conducted in order to study the efficacy and safety of a flavoured solution of delmopinol hydrochloride 2 mg ml-1 (0.2% w/v, Decapinol Mouthwash) used for supervised mouthrinsing in one rinsing group, in comparison with chlorhexidine digluconate 2 mg ml-1 (0.2% w/v, Hibitane Dental) in a second rinsing group, and placebo in the third group. The criteria of the Plaque Index (PI) were used to assess plaque formation. Bleeding on probing (BOP) to the bottom of the pocket with a standard pressure was used as the primary gingivitis assessment. The occurrence of supragingival dental calculus and extrinsic tooth staining were also assessed. In addition, patients were asked to report adverse events at each visit.

RESULTS

Delmopinol and chlorhexidine exhibited lower scores of the mean PI and the BOP percentage than placebo, both at the 3-month and 6-month examinations. Furthermore, both active solutions showed a higher extent of staining of the teeth than placebo during these two observation periods. Rinsing with chlorhexidine resulted in more dental calculus than placebo after 6 months. Chlorhexidine showed lower scores for plaque formation and gingivitis development but higher scores of supragingival dental calculus (after 6 months) and tooth staining than did delmopinol. Both active solutions were reported by the patients--approximately to the same extent but more frequently than placebo--to induce taste alterations and a transient anaesthetic sensation of the oral mucosa. However, subjective staining of the teeth and tongue was reported by 16% of the delmopinol patients, but by 86% of the patients rinsing with chlorhexidine for 6 months. Furthermore, 24% of the patients in the chlorhexidine group, 9% in the delmopinol group and 4% in the placebo group wished to withdraw from treatment.

CONCLUSIONS

The results from this clinical trial indicate that supervised rinsing with 0.2% delmopinol hydrochloride or with 0.2% chlorhexidine digluconate twice daily for 60 s as a supplement to normal mechanical oral hygiene procedures resulted in less plaque formation and gingivitis than rinsing with placebo. Although chlorhexidine was more effective than delmopinol regarding plaque formation and gingivitis, it was considered by the patients as less tolerable.

Acid tolerance response and survival by oral bacteria

Using 21 species of oral bacteria, representing six acidogenic genera, we undertook to determine whether the pH-limiting exponential growth is related to the ability of the organisms to generate an acid-tolerance response that results in enhanced survival at low pH. The lower pH limit of exponential growth varied by more than two units with that of Neisseria A182 at pH 6.34; growth of Lactobacillus casei RB1014 stopped at pH 3.81, with species of Actinomyces, Enterococcus, Prevotella and Streptococcus falling between these limits. The working hypothesis was that the organisms with the higher pH limits for growth are unable to respond to acidic environments in order to survive, whereas the more aciduric organisms would possess or acquire acid tolerance. Adaptation to acid tolerance was tested by determining whether the prior exposure of exponential-phase cells to a low, sub-lethal pH would trigger the induction of a mechanism that would enhance survival at a pH killing pH 7.5 control cells. The killing pH varied from pH 4.5 for Prevotella intermedia ATCC 25611 to pH 2.3 for the three Lactobacillus casei strains in the study, with the three Streptococcus mutans strains killed at pH 3.0 for 3 h. The adaptation experiments revealed three groups of organisms: non-acid-responders, generally representing strains with the highest terminal pH values; weak acid-responders in the middle of the pH list, generating low numbers of survivors at one or two pH values, and the aciduric, strong responders generating a high number of survivors at pH values in the range 6.0 to 3.5, but not at pH 7.5. Predominant among the latter group were the S. mutans and Lactobacilli casei strains, with the most significant adaptive response exhibited by S. mutans LT11 and S. mutans Ingbritt, involving a process that required protein synthesis. Time course experiments with the latter organisms indicated that 90-120 min was required after exposure to the triggering pH before the acid response was fully functional. These results indicate that the sudden exposure of strains of oral streptococci and lactobacilli, as well as Enterococcus faecalis, to pH values between 6.0 and 3.5 results in the induction of an acid tolerance response that enhances the survival of these strains at or below pH 3.5.

Plaque formation and gingivitis after mouthrinsing with 0.2% delmopinol hydrochloride, 0.2% chlorhexidine digluconate and placebo for 4 weeks, following an initial professional tooth cleaning

A double-blind, randomised, 4-week clinical trial with parallel group design in 57 patients with gingivitis was conducted for studying the antibacterial efficacy and safety of a delmopinol HCl aqueous solution 2 mg/ml (0.2% w/v), which was used for unsupervised mouth-rinsing and compared with placebo and chlorhexidine digluconate 2 mg/ml (0.2% w/v, Hibitane Dental, ICI Pharmaceuticals, UK). The plaque index and plaque wet weight were used to measure plaque formation, and gingival fluid flow and bleeding on probing to measure gingivitis. According to the reduction from baseline, chlorhexidine showed a significantly better effect on plaque formation than the placebo after 4 weeks treatment for both plaque measurements. Delmopinol exhibited significantly lower plaque index scores than placebo. The difference between chlorhexidine and delmopinol was not statistically significant for any of the plaque measurements. For gingivitis, no statistically significant differences were obtained between the effects of delmopinol, chlorhexidine and placebo. A transient anaesthetic sensation in the oral mucosa was experienced more clearly by the patients in the delmopinol group than by those using chlorhexidine or placebo rinses. Rinsing with chlorhexidine resulted in more staining of the teeth and tongue than did delmopinol and placebo. The placebo solution tasted better than the 2 active solutions. The results showed that rinsing with either delmopinol HCl aqueous solution 2 mg/ml or chlorhexidine digluconate 2 mg/ml 2x daily for 60 as a supplement to normal oral hygiene, following an initial professional tooth cleaning, leads to a lower plaque formation than rinsing with placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of plaque and gingivitis after mouthrinsing with 0.2% delmopinol hydrochloride

A double-blind, randomized, 2-wk experimental gingivitis clinical trial with cross-over design in 14 dental students was conducted in order to study the efficacy and safety of delmopinol hydrochloride solution (2 mg/ml), used with no other oral hygiene procedures, in comparison with placebo. Plaque formation was measured by the Quigley & Hein Plaque Index and gingivitis was assessed by bleeding on probing according to Mühlemann & Son. Rinsing with delmopinol resulted in lower plaque scores compared to placebo. The development of gingivitis was weak during the 2-wk test periods, and thus no conclusive results were obtained. As in previous studies, the most frequent adverse event when rinsing with delmopinol was a transient anaesthetic sensation in the oral mucosa. The results showed that rinsing with delmopinol hydrochloride solution (2 mg/ml) for 60 s twice daily with no other oral hygiene procedures led to less plaque formation than rinsing with placebo. This study also showed good tolerance and acceptability of mouthrinsing with delmopinol.

Delmopinol interactions with cell walls of gram-negative and gram-positive oral bacteria

The main purpose of the present study was to investigate the influence of delmopinol hydrochloride on the cell surface morphology of gram-negative and gram-positive bacterial cells by using transmission electron microscopy. A second purpose was to evaluate the extraction of cell wall material caused by delmopinol and the binding of radiolabelled delmopinol to the various strains. Fresh isolates and type strains of gram-negative rods associated with periodontal disease, Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and strains of the gram-positive streptococci Streptococcus sanguis, Streptococcus mutans and Streptococcus salivarius, were exposed to 3.2 mM (0.1%) or 6.4 mM (0.2%) delmopinol hydrochloride from 1 to 90 min. For electron microscopy the cells were fixed and negatively contrast-stained. Treatment with 6.4 mM delmopinol for 1 min resulted in marked ultrastructural changes of cell wall components and the outer cell membrane of the 3 gram-negative species compared with control cells, whereas the gram-positive streptococci treated with delmopinol showed little or no morphologic alteration as compared with untreated cells. The result from the electron microscopy was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins released from bacterial cells treated as for electron microscopy. More material was extracted from the gram-negative rods than from the gram-positive cocci. Significantly more delmopinol bound to the gram-negative rods than to the streptococci. It appears that the amphiphilic properties of delmopinol make gram-negative rods more vulnerable to delmopinol than gram-positive streptococci.