Similarity of the effects of erythritol and xylitol on some risk factors of dental caries.

Several sugar alcohols (polyols) have been promoted as potential sugar substitutes in caries limitation. However, differences in the effects of simple alditol-type sugar alcohol homologues on dental plaque have not been compared in clinical tests. The effects of 6-month use of erythritol (a sugar alcohol of the tetritol type), xylitol (a pentitol) and D-glucitol (sorbitol, a hexitol) were investigated in a cohort of 136 teenage subjects assigned to the respective polyol groups or to an untreated control group (n = 30-36 per group). The daily use of the polyols was 7.0 g in the form of chewable tablets, supplemented by twice-a-day use of a dentifrice containing those polyols. The use of erythritol and xylitol was associated with a statistically significant reduction (p < 0.001 in most cases) in the plaque and saliva levels of mutans streptococci. The amount of dental plaque was also significantly reduced in subjects receiving erythritol and xylitol. Such effects were not observed in other experimental groups. Chemical analyses showed D-glucitol to be a normal finding in dental plaque while xylitol was less consistently detected. Erythritol was detected in measurable amounts only in the plaque of subjects receiving this polyol. Erythritol and xylitol may exert similar effects on some risk factors of dental caries, although the biochemical mechanism of the effects may differ. These in vivo studies were supported by cultivation experiments in which xylitol, and especially erythritol, inhibited the growth of several strains of mutans streptococci.

Comparison of erythritol and xylitol saliva stimulants in the control of dental plaque and mutans streptococci.

The effect of 2-month usage of saliva-stimulating pastils containing either erythritol or xylitol was studied in a cohort of 30 subjects assigned to the respective polyol groups (n = 15). The daily consumption level of both polyols was 5.2 g, used in 5 daily chewing episodes. The mean weight of total plaque mass (collectable during a standard period of 3 min from all available tooth surfaces) was reduced significantly in the xylitol-group, while no such effect was observed in the erythritol-group. This reduction in plaque mass was accompanied by a significant reduction in the turbidity readings (A(660)) of aqueous plaque suspensions; no such effect was observed in the erythritol-group. However, plaque protein levels did not differ between baseline and endpoint in either polyol group. The plaque and salivary levels of Streptococcus mutans and plaque levels of total streptococci were reduced significantly in the xylitol-group, while no such effect was detected in the erythritol-group. However, either polyol regimen had no effect on plaque levels of S. sobrinus. The results suggest that systematic use of xylitol-containing saliva stimulants may be more effective in controlling some oral-hygiene-related and caries-associated parameters than similar use of erythritol-containing products. The results also speak for a special relationship between xylitol and S. mutans. However, owing to the great potential of erythritol as a caries-reducing agent -- based on the tetritol nature of erythritol -- the present laboratory results should be considered preliminary and subject to verifying clinical studies.

The optimum time to initiate habitual xylitol gum-chewing for obtaining long-term caries prevention.

Habitual xylitol gum-chewing may have a long-term preventive effect by reducing the caries risk for several years after the habitual chewing has ended. The goal of this report was (1) to determine if sorbitol and sorbitol/xylitol mixtures provide a long-term benefit, and (2) to determine which teeth benefit most from two-year habitual gum-chewing - those erupting before, during, or after habitual gum-chewing. Children, on average 6 years old, chewed gums sweetened with xylitol, sorbitol, or xylitol/sorbitol mixtures. There was a "no-gum" control group. Five years after the two-year program of habitual gum-chewing ended, 288 children were re-examined. Compared with the no-gum group, sorbitol gums had no significant long-term effect (relative risk [RR], 0.65; 95% confidence interval [c.i.], 0.39 to 1.07; p < 0.18). Xylitol gum and, to a lesser extent, xylitol/sorbitol gum had a long-term preventive effect. During the 5 years after habitual gum-chewing ended, xylitol gums reduced the caries risk 59% (RR, 0.41; 95% c.i., 0.23 to 0.75; p < 0.0034). Xylitol-sorbitol gums reduced the caries risk 44% (RR, 0.56; 95% c.i., 0.36 to 0.89; p < 0.02). The long-term caries risk reduction associated with xylitol strongly depended on when teeth erupted (p < 0.02). Teeth that erupted after 1 year of gum-chewing or after the two-year habitual gum use ended had long-term caries risk reductions of 93% (p < 0.0054) and 88% (p < 0.0004), respectively. Teeth that erupted before the gum-chewing started had no significant long-term prevention (p < 0.30). We concluded that for long-term caries-preventive effects to be maximized, habitual xylitol gum-chewing should be started at least one year before permanent teeth erupt.

The optimum time to initiate habitual xylitol gum-chewing for obtaining long-term caries prevention

Habitual xylitol gum-chewing may have a long-term preventive effect by reducing the caries risk for several years after the habitual chewing has ended. The goal of this report was (1) to determine if sorbitol and sorbitol/xylitol mixture provide a long-term benefit, and (2) to determine which teeth benefit most from two-year habitual gum-chewing - those erupting before, during, or after habitual gum-chewing. Children, on average 6 years old, chewing gums sweetened with xylitol, sorbitol, or xylitol/sorbitol mixture. There was a "no gum" control group. Five years after the two-year program of habitual gum-chewing ended, 288 children were re-examined. Compared with the no-gum group, sorbitol gums had no significant long-term effect (relative risk (RR), 0.65; 95 percent confidence interval [c.i]. 0.39 to 1.07; p < 0.18). Xylitol gums and, to a lesser extent, xylitol/sorbitol gum had a long-term preventive effect. During the 5 years after habitual gum-chewing ended, xylitol gums reduced the caries risk 59 percent (RR, 0.41; 95 percent c.i., 0.23 to 0.75; p < 0.0034). Xylitol-sorbitol gums reduced the caries risk 44 percent (RR, 0.56; 95 percent c.i., 0.36 to 0.89; p < 0.02). The long-term caries risk reduction associated with xylitol strongly depended on when teeth erupted (p < 0.02). Teeth that erupted after 1 year of gum-chewing or after the two-year habitual gum use ended had long-term caries risk reduction of 93 percent (p < 0.0054) and 88 percent (p < 0.0004), respectively. Teeth that erupted before the gum-chewing started had no significant long-term prevention (p < 0.30). We concluded that for long-term caries-preventive effects to be maximized, habitual xylitol gum-chewing should be started at least one year before permanent teeth erupt.(AU)

Physical, chemical, and histologic changes in dentin caries lesions of primary teeth induced by regular use of polyol chewing gums.

A previous clinical trial showed that long-term use of saliva-stimulating polyol (xylitol and sorbitol) chewing gums was associated with arrest of dental caries in young subjects. After a 20-22-month intervention (when the subjects were 8 years old), a total of 23 primary teeth with extensive dentin caries lesions whose surface in clinical examination was found to be totally rehardened (remineralized) could be removed because the teeth were near their physiologic exfoliation time. These teeth were subjected to histologic, microhardness, and electron microscopic tests. The majority of the specimens had been remineralized from the surface by a non-cellular-mediated process within the remaining collapsed, organic extracellular matrix associated with the remaining dentinal surface. Many of the underlying dentinal tubules were filled with a matrix that had been subsequently mineralized. Dental microanalyses showed that the topmost (outer) 20-microm-thick rehardened layer of the lesions exhibited the highest Ca:P ratio, which leveled off at a depth of approximately 150 microm. The rehardened surface layer (normally <0.1 mm in thickness) was significantly (P < 0.001) harder than sound dentin and nearly as hard as sound enamel. Although the main source of the mineral present in the rehardened layer was most likely of salivary origin, some extracellular remineralization was probably mediated by odontoblasts. The results complete the dinical diagnoses of the original trial and suggest that regular use of polyol chewing gums may induce changes in dentin caries lesions, which in histologic and physiochemical studies show typical characteristics of rehardening and mineralization.

Polyol-combinant saliva stimulants: a 4-month pilot study in young adults.

Several studies indicate that xylitol (X) consumption is associated with certain biochemical changes in dental plaque and whole saliva. In making X-containing saliva stimulants more cost-effective and palatable, manufacturers may use maltitol syrup (MS, which normally contains some sorbitol and higher polyols) or polydextrose (PD, a polysaccharide molecule with a mass > 22 kDa) as bulking agents. Combinations of X with MS and PD have not been tested regarding their salivary effects. One hundred and eighty-eight young subjects (mean age, 22 years) of both sexes were divided into three groups of equal size for a 4-month study. The subjects in one group used X-MS dragees (in 7 daily episodes; 8 g X per day), while the subjects in another group used X-PD dragées in as many daily episodes (8 g X per day). Subjects in the third (comparison) group did not receive saliva stimulants. Paraffin-stimulated whole saliva samples were collected at baseline, after 2 months, and at endpoint. The usage of X-MS was associated with a significant (P < 0.05) reduction in the salivary sucrase activity. After 4 months, the activity of enzymes hydrolyzing N(alpha)-benzoyl-DL-arginyl-p-nitroaniline was significantly reduced in all groups, while the levels of free sialic acid were reduced in group X-PD only (P < 0.05). These salivary changes most likely reflected microbial shifts in the oral cavity and suggest that information from saliva studies may be of avail when deciding which bulking agents should be used in xylitol-based saliva stimulants.

A descriptive report of the effects of a 16-month xylitol chewing-gum programme subsequent to a 40-month sucrose gum programme.

A previous caries trial (Belize studies) involved the usage of sucrose chewing-gum for a period of 40 months in one group of initially 10-year-old subjects in an environment of high sugar consumption, high caries activity, and limited access to restorative care. After the termination of the 40-month supervised sucrose gum usage, the 109 subjects of the original sucrose group retrieved at the endpoint of the original trial were invited to participate in a xylitol chewing-gum programme (involving the usage of the '100% pellet-shaped formular') for 16 months. The average daily consumption level of xylitol was up to 14 g per subject, normally used in seven daily chewing episodes. Although most subjects used chewing-gum at schools and received their gum portions from a school official, gum chewing during these 16 months was mostly unsupervised. After 16 months, 83 subjects (76%; mean age 14.9 years) were retrieved. The caries status of these subjects was examined by the same calibrated, blinded examiners as in the original trial. To mask the examiners, 141 similar non-participating subjects were recruited from the same school classes and were examined in a random order with the gum-using subjects, according to the same standard routine. The intensified xylitol gum usage for 16 months was associated with a reduction of the mean DMFS score from 10.9 (at 40 months) to 9.3 (at 56 months, p = 0.0013) and a reduction in caries rate from 20.1 caries onsets per 1,000 surface-years (40-month period average rate) to 10.2 caries onsets per 1,000 surface-years. The reduction in DMFS score resulted mostly from the change in the D component of the index and possibly reflected a stabilisation of the caries process and rehardening of some caries lesions to a non-progressive carious state.

gamma-Glutamyltransferase from the outer cell envelope of Treponema denticola ATCC 35405.

The human oral spirochete Treponema denticola ATCC 35405 was shown to exhibit relatively high enzyme activity toward the gamma-glutamyl amide bond present in N-gamma-L-glutamyl-4-nitroaniline. The enzyme responsible for this catalysis (gamma-glutamyltransferase [GGT]; EC 2.3.2.2) was purified by means of fast protein liquid chromatography to two sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-pure forms from a mild (0.1%) Triton X-100 extract of washed cells. The GGT was studied primarily with regard to its hydrolytic activity by using N-gamma-L-glutamyl-4-nitroaniline as a substrate, although the GGT was shown to catalyze transpeptidation reactions. The high-molecular-mass form of the GGT gave a value of about 213 kDa by SDS-PAGE when heat treatment was omitted and one of 26 kDa after heat treatment; mass spectrometry gave a value of 26.877. The larger form may represent an aggregate with nonprotein structures (possibly of a carbohydrate nature). The preliminary N-terminal sequence of the GGT is MKKPLIGITGSXLYETSQXXF. The enzyme was highly active on glutathione, transferring its Glu residue either to a water molecule or to the Gly-L-Leu dipeptide. The GGT stability was absolutely dependent on the presence of free thiol(s), while no evidence of metalloenzyme nature was obtained. The proposed location of the GGT in the outer cell envelope and its high activity on glutathione, a major nonprotein thiol present in virtually all cells, suggest that the GGT may play a role in the propagation of T. denticola within inflamed periodontal tissues.

The peptidolytic capacity of the spirochete system.

Relatively scant chemical information has been available on the proteinases and peptidases of spirochetes in spite of the association of spirochetes with several serious infections known to plague humans and other animal species. This situation has partly resulted from difficulties in growing some spirochetes under laboratory conditions. The cells of Treponema denticola, a spirochete suggested to be associated with periodontal infections, have turned out to be a good source of new chemical information on those enzymes. Latest studies suggest that the outer cell envelope or the periplasmic space of T. denticola contains several novel proteinases and peptidases (hence called "ectoenzymes") which may contribute to the chronicity of periodontal infections. Some of the oligopeptidases discovered are specific for proline-containing host tissue peptides such as substance P, bradykinin, neurotensin, etc., and possibly small collagen fragments. The only spirochetal peptidases purified to give a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis have been obtained from T. denticola. One particular peptidase, suggested to be similar to the oligopeptidase B (EC 3.4.21.83) of Escherichia coli seems to be present in the cell envelope or in the periplasmic space at quite large concentrations. The presence of this and several other peptidases in the outer cell structures of the treponemes suggests that such enzymes are important for the nutrition of these highly motile and invasive organisms. The biological role of these enzymes can thus be envisaged in the peptidolytic processing of host tissue proteins and peptides to gradually smaller molecules to fulfill the nutritional requirements of these organisms. Although the genetic similarity between T. denticola and some other treponemes and spirochetes can be hotly debated, it is nevertheless now possible to use T. denticula enzymes as suitable objects for comparison when the chemistry of other spirochetes is studied.

Polyol-combinant saliva stimulants and oral health in Veterans Affairs patients--an exploratory study.

An exploratory study investigated the root caries incidence in Department of Veterans Affairs patients with exposed root surfaces. For a period of six to 30 months, the subjects were systematically assigned to groups which used chewable dragees or chewing gums that contained either xylitol or sorbitol as bulk sweeteners. The mean treatment time was 1.8 years (standard deviation = 0.8). The consumption levels of both polyols was up to 8.5 g daily, used typically in five episodes during a 16-hour period. The subjects were examined every six months in connection with their standard scheduled visits at the Veterans Affairs Medical Center. The risk for a root-surface lesion in the xylitol group was only 19% of that for a surface in the sorbitol group (relative risk, 0.19; 95% confidence interval, 0.06-0.62; p < or = 0.0065). Simultaneous study in periodontal patients showed that both polyols significantly reduced the gingival index scores, and slightly (but not significantly) reduced the plaque index scores. Collectively, both studies suggest that frequent daily consumption of chewable, saliva-stimulating products containing essentially nonfermentable or slowly fermentable dietary carbohydrate sweeteners (xylitol and sorbitol) may have an oral-health-improving effect in Department of Veterans Affairs Medical Center patients. It is necessary to evaluate if these procedures would be efficacious in larger and expanded patient cohorts.

Proline iminopeptidase from the outer cell envelope of the human oral spirochete Treponema denticola ATCC 35405.

Certain periodontopathic organisms have been shown to exhibit high activity of proline iminopeptidase (PIPase). The human oral spirochete Treponema denticola ATCC 35405 was found to contain an easily extractable, novel PIPase (EC 3.4.11.5), which was purified to a sodium dodecyl sulfate- polyacrylamide gel electrophoresis-pure form by means of fast protein liquid chromatographic procedures. The range of the minimum monomeric molecular mass (280 amino acid residues) of the PIPase, based on amino acid analysis, was 30.35 to 30.39 kDa, but the likely in vivo form of the enzyme is a tetramer (minimum mass, 120.2 to 120.4 kDa). The molecular masses based on laser desorption mass spectrometry were 36.058 kDa for the monomer and 72.596 kDa for a dimer. The PIPase cleaves specifically the Pro-Y bond in dipeptides where Y is preferably Arg or Lys. Pro-Gln, Pro-Asn, and Pro-Ala were also good substrates, while Pro-Glu was hydrolyzed slowly and Pro-Asp was not hydrolyzed at all. Tripeptides were poor substrates or were not hydrolyzed (an exception was Pro-Gly-Gly, which cleaved at a moderate rate). Larger molecules, such as poly-L-Pro, were not hydrolyzed. The T. denticola enzyme can be regarded as a true PIPase, since replacing Pro in Pro-Y with other amino acid residues resulted in no hydrolysis. The activity of the PIPase may depend on an active carboxyl group and on an active seryl residue but not on metal cations. Diethylpyrocarbonate inactivated the enzyme in a reaction that was not reversible upon addition of NH2OH. The enzyme contains a relatively large percentage (ca. 15%) of proline residues. The dominance of the PIPase activity among aminopeptidase activities present in T. denticola and the proposed location of the enzyme in the outer cell envelope suggest that it has a vital function in the propagation of the cells within their biological niche (inflamed human periodontal tissues). The biologic role of the PIPase may be envisaged as in the termination of the overall peptidolytic cascade (liberating free proline and other amino acids), whereby host tissue proteins and peptides are first processed and inactivated by other peptidases possibly present within the same confines as the PIPase.

Conclusion and review of the Michigan Xylitol Programme (1986-1995) for the prevention of dental caries.

The major results of the Michigan Xylitol Programme (1986-1995) are summarised. The Programme consisted of several clinical trials and laboratory investigations designed to study the usage of xylitol-containing saliva stimulants in the prevention of dental caries. The trials patients included young (initially 6 year olds) and adult or geriatric subjects who were given saliva stimulants (mostly chewing gum) for periods of two weeks to 56 months. A special rationale behind these studies was the need to further test the validity of the 'pentitol-hexitol theory' in the prevention of caries. This theory has maintained that pentitols (sugar alcohols with five hydroxyl groups, such as xylitol) may be cariologically more effective than hexitols (sugar alcohols with six hydroxyl groups, such as sorbitol). The accumulated clinical, sialochemical and microbiologic evidence suggests that xylitol, a natural carbohydrate sweetener of the pentitol type, is more effective in preventing dental caries than sorbitol, and cariologically safer than sorbitol, a natural carbohydrate of the hexitol type. Sorbitol was found to be significantly less cariogenic than sucrose. The Programme's results shed additional light on the cariologic and oral biologic effects of natural, dietary polyols, and suggest that the usage of xylitol chewing gum (and in some cases xylitol dragées) can be considered a valuable additional tool in caries prevention and in stabilisation of caries in all age groups.

Properties of whole saliva and dental plaque in relation to 40-month consumption of chewing gums containing xylitol, sorbitol of sucrose.

Samples of whole saliva and dental plaque were collected from initially 10-year old subjects who participated in a 40-month cohort study investigating the effect of chewing gum usage on caries rates. The subjects represented nine cohorts of which one did not receive gum, while in eight cohorts the subjects received gum containing either xylitol, sorbitol, their mixtures, or sucrose as bulk sweeteners, the maximum sweetener consumption in the form of gums being up to 10.7 g/day, used in 3-5 daily chewing episodes. Gum usage had no significant effect on the levels of salivary protein, IgA, alpha-amylase, peroxidase, lysozyme, SCN and buffer capacity. At the endpoint, the group that received 100% xylitol pellet-shaped gum five times/day, had significantly lower levels of sucrase (p <0.05) and free sialic acid (p < 0.001) in whole saliva than at baseline. This group showed significantly (p <0.05) smaller plaque index scores at two cross-sectional measurements, and exhibited the lowest log(10) counts of salivary lactobacilli at endpoint than most other groups. The salivary levels of peptidase(s) (oligopeptidase B-like enzymes) hydrolyzing N-alpha-benzoyl-DL-arginyl-p-nitroaniline were significantly (p<0.05) or almost significantly lower in groups which received 100% xylitol pellet gums. All groups exhibited obviously an aging-related increase of salivary mutans streptococcus scores, except the above xylitol group in which the mean scores did not change.

Polyol chewing gums and caries rates in primary dentition: a 24-month cohort study.

The effect of 2-year chewing-gum use on the caries rates of primary teeth was studied in a combined school and home program in a sample of 510 initially 6-year-old subjects with high caries experience, low availability of fluoride, and difficult access to dental care. The gum, formed into either sticks or pellets, comprised either xylitol, sorbitol, or mixtures thereof. The gum was chewed for 5 min under supervision five times a day during the school year, and for variable times during nonschool days. Seven groups were studied. One group received no gum; two xylitol gum groups received either pellet or stick gum as did, two sorbitol gum groups, and two groups received either of two types of xylitol/sorbitol pellet gum. The response variable was the development of a frank carious lesion detectable by physical loss of enamel and probable extension to the dentin for those surfaces of primary teeth that were not cavitated at baseline. Caries rates associated with the use of each of the gum types were compared to the caries rates in the no-gum group. The usage of all polyol gums resulted in a significant decrease of the caries onset rate (p < 0.05). The caries onset risk for a primary surface in the xylitol pellet and the sorbitol pellet groups was 35 and 44% of that in the no-gum group (relative risk, 0.35; 95% confidence interval, 0.21-0.59; relative risk, 0.44; 95% confidence interval, 0.30-0.63, respectively). The caries onset risk in the xylitol stick gum group was 53% of that in the no-gum group (relative risk, 0.53; 95% confidence interval, 0.39-0.72), which was marginally (p = 0.1520) lower than in the sorbitol stick gum group (relative risk, 0.70; 95% confidence interval, 0.52-0.94). The usage of both xylitol/sorbitol mixtures in pellet form was associated with a caries onset rate comparable with the usage of the xylitol stick gum. The largest caries risk reduction was observed in the group receiving xylitol pellet gum.

Analysis in gingival crevicular fluid of two oligopeptides derived from human hemoglobin beta-chain.

HPLC on a reversed phase column, amino acid sequencing and mass spectrometry were used to determine the structure of two human gingival crevicular exudate oligopeptides (Leu-Thr-Pro-Glu-Glu-Lys-Ser-Ala-Val-Thr-Ala-Leu and Leu-Val-Val-Tyr-Pro-Trp-Thr-Gln-Arg-Phe) which were shown to have been derived from the beta-chain of hemoglobin. These sequences may simply represent two degradation products of the beta-chain. However, their preservation in an exudate characterized by active peptidolysis may also prompt the question about their possible more specific role.

Xylitol chewing gums and caries rates: a 40-month cohort study.

Dental caries is a pandemic infectious disease which can affect the quality of life and consumes considerable health care resources. The chewing of xylitol, sorbitol, and even sugar gum has been suggested to reduce caries rates. No clinical study has simultaneously investigated the effectiveness of these gums when compared with a group receiving no chewing gum. A 40-month double-blind cohort study on the relationship between the use of chewing gum and dental caries was performed in 1989-1993 in Belize, Central America. One thousand two hundred and seventy-seven subjects (mean age, 10.2 years) were assigned to nine treatment groups: one control group (no supervised gum use), four xylitol groups (range of supervised xylitol consumption: 4.3 to 9.0 g/day), two xylitol-sorbitol groups (range of supervised consumption of total polyols: 8.0 to 9.7 g/day), one sorbitol group (supervised consumption: 9.0 g/day). The gum use during school hours was supervised. Four calibrated dentists performed the caries registrations by means of a modified WHO procedure. The primary endpoint was the development of an unequivocal caries lesion on a non-cavitated tooth surface. Compared with the no-gum group, sucrose gum usage resulted in a marginal increase in the caries rate (relative risk, 1.20; 95% confidence interval,0.96 to 1.49; p = 0.1128). Sorbitol gum significantly reduced caries rates (relative risk 0.74; 95% confidence interval, 0.6 to 0.92 ; p = 0.0074). The four xylitol gums were most effective in reducing caries rates, the most effective agent being a 100% xylitol pellet gum (relative risk, 0.27; 95% confidence interval, 0.20 to 0.36; p = 0.0001). This gum was superior to any other gum (p < 0.01). The xylitol-sorbitol mixtures were less effective than xylitol, but they reduced caries rates significantly compared with the no-gum group. DMFS analyses were consistent with these conclusions. The results suggest that systematic usage of polyol-based chewing gums reduces caries rates in young subjects, with xylitol gums being more effective than sorbitol gums.

Role of the chymotrypsin-like membrane-associated proteinase from Treponema denticola ATCC 35405 in inactivation of bioactive peptides.

The ability of washed whole cells of Treponema denticola ATCC 35405 to hydrolyze (inactivate) substance P, bradykinin, and angiotensin I was studied. Substance P was attacked primarily at the Phe-8-Gly-9 bond by a chymotrypsin-like proteinase (CTLP), at Pro-4-Gln-5 by an endo-acting prolyl oligopeptidase (POPase), and at Gln-5-Gln-6 by an endopeptidase (FALGPA-peptidase). Bradykinin was cleaved at Phe-5-Ser-6 by the FALGPA-peptidase and at Pro-7-Phe-8 by the POPase. Angiotensin I was rapidly converted to angiotensin II by the CTLP, and both angiotensin I and angiotensin II were further hydrolyzed at Pro-7-Phe-8 by the POPase. All these enzymes were assumed to be cell associated and were easily extracted with a mild (0.05 to 0.1%) Triton X-100 treatment. Because it was conceivable that the hydrolysis of substance P at the Phe-8-Gly-9 bond was catalyzed by a CTLP described earlier (V.-J. Uitto, D. Grenier, E. C. S. Chan, and B. C. McBride, Infect. Immun. 56:2717-2722, 1988), the enzyme was purified to homogeneity by means of conventional fast protein liquid chromatography procedures. For kinetic studies, Phe-8(4-nitro)-substance P (NSP) (absorption maximum at 309.2 nm, epsilon = 545 M-1 cm-1) was synthesized to replace substance P as a substrate in kinetic studies. In reversed-phase chromatography, both NSP and substance P gave identical results with both whole cells and the purified enzyme. The CTLP has a mass of 95 kDa, and its activity is suggested to be based on an active seryl residue, on an active imidazole group, and on an active carboxyl group but not on metal cations. The enzyme hydrolyzes N-succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroaniline (SAAPFNA, a typical chymotrypsin substrate) at a high rate and several proteins, such as calf thymus histone, human plasma fibrinogen, milk caseins, and gelatin. Among the substrates tested, substance P showed the highest affinity (Km = 0.22 mM) for the purified enzyme. Depending on conditions, clinically applicable chlorhexidine levels (3.2 mmol/liter, or 0.2%) strongly activated (up to fourfold) the hydrolysis of SAAPFNA by whole cells and the purified CTLP. The hydrolysis of NSP by whole cells and purified CTLP was slightly inhibited by chlorhexidine. The results demonstrated the versatility and the effectiveness of the outer membrane of T. denticola in occasioning a rapid breakdown and inactivation of human bioactive peptides and other peptidolytic catalyses.(ABSTRACT TRUNCATED AT 400 WORDS)

Saliva stimulants and the oral health of geriatric patients.

Root-surface caries (RSC) has been recognized as a specific and important dental disease. Significant advances have been made in the pathology and microbiology of RSC, and the need to standardize the guidelines for recording RSC data has been recognized. Researchers have emphasized the increasing impact RSC will have on the geriatric population, especially since the methods to treat and prevent this disease are limited. The purpose of this study was to investigate the possibility of limiting RSC in a Veterans Administration (VA) patient population, using polyol-containing saliva stimulants that were voluntarily consumed by residents of a VA Medical Center (VAMC) over a period of from six to 30 months. Another aim was to study the effect of this program on the gingival health of periodontal patients.

Purification and general properties of an oligopeptidase from Treponema denticola ATCC 35405--a human oral spirochete.

An endo-acting oligopeptidase (OPase) was purified to homogeneity from the cells of Treponema denticola ATCC 35405--a human oral spirochete--by a procedure that comprised a mild Triton X-100 extraction (which disintegrates the outer membrane but leaves the cells morphologically intact) and four successive fast protein liquid chromatographic steps of the extract. The activity of this oligopeptidase (formerly named "trypsin-like" enzyme and "BANA-peptidase") together with the proteinase activities of T. denticola and Porphyromonas gingivalis is utilized in a diagnostic test for human periodontal infections, but the enzyme's chemical nature has not been studied. The enzyme is a cell-associated 78-kDa protein with an isoelectric point of 6.1, and its estimated minimum peptide length was 688 amino acid residues. The OPase does not hydrolyze proteins, but hydrolyzes -X-Arg-p-nitroaniline peptides between arginine and the chromogen, the optimum pH of hydrolysis covering a broad pH range (7 to 9). The OPase is not a metalloenzyme, although 1.0 mmol/liter Ca(II) increases the rate of the hydrolysis of all substrates. Ca(II) did not affect the values of the Michaelis constant. The OPase activity is not dependent on reactive SH-groups, but is suggested to depend on the catalytic triad COOH. . .His. . .Ser. The N-terminal sequence for the first 29 amino acid residues is MKQSDFEKPPIAEIKETRFEKFGKTRIDN. The purified enzyme is very sensitive to chlorhexidine acetate (mixed inhibition; Ki = 0.85 microM) and somewhat less sensitive to bacitracin (Ki(app) = 27.5 microM). The present OPase is considered to belong to the serine peptidases, functionally resembling trypsin except that the OPase does not hydrolyze proteins. The OPase may be regarded as an oligopeptidase, the substrate specificity profile of which resembles to a certain extent that of some members of the coagulation cascade.

Stabilisation of rampant caries: polyol gums and arrest of dentine caries in two long-term cohort studies in young subjects.

The purpose of this paper is to report clinical observations on the stabilisation of dentine caries in two chewing gum studies carried out in young subjects. One study focused on the permanent dentition of 1,277 initially 10-year old subjects, while the other study was carried out on 510 initially 6-year old subjects and focused on the primary dentition. In both trials, several chewing gum formulas containing dietary polyols (xylitol and sorbitol, or their combinations) were used for up to 40 months (10-year olds) or up to 24 months (6-year olds). The daily consumption level of both polyols was up to 10.7 g per subject, used normally in 5-minute chewing episodes 3 to 5 times per day. Supervised chewing in schools lasted 5 min per episode, and for variable times during non-school days. Rehardening of dentine caries lesions was observed clinically by experienced, blinded examiners using sharp dental explorers and fibre optic light. After 40 months (permanent dentition) or after 18 months (primary dentition), rehardening (caries arrest) generally occurred more frequently in subjects who used polyol gums than in subjects who did not receive gum as part of the programmes, or who received sucrose gum. Arrest or non-progression of dentine caries was most frequently observed in subjects who used 100 per cent xylitol gums or mixtures of xylitol and sorbitol, but the differences between gums were not consistently significant. However, the usage of 100 per cent xylitol pellet-shaped gum was more frequently associated with arrest of dentine caries than other treatments. These results and previous studies suggest that high-xylitol chewing gum usage can retard or arrest even rampant dentine caries in conditions where effective restoration and prevention programmes have not been instituted, and can also provide additional protection against further caries development during full implementation of restorative procedures by holding the lesion in a non-progressive condition.