Demineralization and remineralization of root surface caries

Association between periodontitis and dental caries: a systematic review and meta-analysis

OBJECTIVES

Recent evidence suggested a link between periodontitis (PD) and dental caries, but the trends and nature of this association remained unclear. The overall aim of this study was to critically assess the correlation of two disorders.

METHODS

A comprehensive search was conducted within the PUBMED and EMBASE databases including grey literatures up to July 5th, 2023. The Newcastle-Ottawa scale was used to qualitatively evaluate the risk of bias.

RESULTS

Overall, 18 studies were included. In terms of caries risk in PD patients, the prevalence of caries was increased by PD (OR = 1.57, 95%CI:1.20-2.07), both in crown (OR = 1.03, 95%CI:1.01-1.05) and root caries (OR = 2.10, 95%CI:1.03-4.29). Odds of caries were also raised by PD severity (OR moderate = 1.38, 95%CI:1.15-1.66; OR severe = 2.14, 95%CI:1.74-2.64). Besides, patients with PD exhibited a higher mean number of decayed, missing and filled teeth (DMFT) and decayed and filled root teeth (DFR) [weighted mean difference (WMD)DMFT = 0.87, 95%CI: -0.03-1.76; WMDDFR = 1.13, 95%CI: 0.48-1.78]. Likewise, patients with caries had an elevated risk of PD (OR = 1.79, 95%CI:1.36-2.35). However, Streptococcus mutans, one of the main pathogens of caries, was negatively correlated with several main pathogens of periodontitis.

CONCLUSIONS

This study indicated a positive correlation between dental caries and periodontitis clinically, while the two disease-associated pathogens were antagonistic.

CLINICAL RELEVANCE

Further research, including clinical cohort studies and mechanisms of pathogens interaction is needed on this link for better prevention and treatment of PD and caries. In addition, innovative prevention strategies need to be developed and incorporated in dental practices to prevent these two highly prevalent oral diseases.

The In Vitro Effect of Laser Irradiation (Er:YAG and CO2) and Chemical Reagents (Hydrogen Peroxide, Sodium Hypochlorite, Chlorhexidine, or Sodium Fluoride) Alone or in Combination on Reducing Root Caries Bacteria

(1) Lasers have been used for the treatment of dentinal hypersensitivity and bacterial reductions in periodontology. The purpose of this in vitro study was to evaluate the effect of Carbon Dioxide (CO₂) and Erbium-doped Yttrium Aluminum Garnet (Er:YAG) lasers with chlorhexidine (CHX), hydrogen peroxide (H₂O₂), sodium hypochlorite (NaOCl), or sodium fluoride (NaF) on the viability of oral bacteria associated with root caries. (2) Streptococcus mutans, Streptococcus sanguinis, and Enterococcus faecalis were grown in Brain Heart Infusion (BHI) broth, diluted to an OD660 of 0.5, and treated with antiseptics with or without simultaneous irradiation with the Er:YAG and CO₂ lasers for 30 s repeated three times. The treatment groups consisted of 1: no treatment, 2: 0.5% H₂O₂ alone, 3: 0.5% NaOCl alone, 4: 0.12% CHX alone, 5: 2% NaF alone, 6: laser alone, 7: laser with 0.5% H₂O₂, 8: laser with 0.5% NaOCl, 9: laser with 0.12% CHX, and 10: laser with 2% NaF for both lasers. The microbial viability was determined through plating and viable colonies were counted, converted into CFU/mL, and transformed into log form. The statistical analysis was performed using a two-tailed paired t-test. (3) The use of CO₂ and Er:YAG lasers alone failed to show statistically significant antibacterial activity against any of the bacteria. The only effective monotreatment was CHX for S. mutans. The combined treatment of 0.5% NaOCl with Er:YAG produced the greatest reduction in overall viability. (4) The combination of the Er:YAG laser with 0.5% NaOCl resulted in the largest reduction in bacterial survival when compared to monotherapies with antimicrobial solutions or lasers.

Cariogenicity induced by commercial carbonated beverages in an experimental biofilm-caries model

Objectives

Frequent consumption of sugars-containing carbonated beverages has been associated with caries, but the consequences on the dental biofilm remain unclear. The aim was to evaluate the effect of commercial carbonated beverages and their sugar-free version on enamel and dentine demineralization and on the cariogenic properties of Streptococcus mutans biofilms.

Materials and Methods

Biofilms of S. mutans UA159 were grown on enamel and dentin slabs and exposed 3 times/day for 5 min, to a commercial cola or orange-flavored carbonated beverage or to their sugar-free version. Biofilms/slabs were recovered to assess biomass, viable microorganisms, protein content and polysaccharides. Demineralization was estimated by the variation of Knoop surface microhardness.

Results

Exposures to the biofilm with sugars-containing carbonated beverages resulted in similar biomass, viable microorganisms, proteins, and polysaccharides than sucrose (P < 0.05). The sugar-free cola and orange-flavored drink showed lower effect on the biofilm, as compared with sucrose or their sugared version (P < 0.05). All of the products tested, included the sugar-free, showed higher demineralization than the negative control (P < 0.05).

Conclusions

Sugars-containing carbonated beverages enhance cariogenic activity of S. mutans biofilms, comparable with sucrose. Sugar-free carbonated beverages also have a high demineralizing potential, without affecting biofilm properties.

Assessment of root caries under wet and dry conditions using swept-source optical coherence tomography (SS-OCT)

The purpose of this study was to compare optical properties of root caries under two observing conditions using swept-source optical coherence tomography (SS-OCT). In vitro and natural root caries were observed by SS-OCT under wet and dry conditions, followed by confocal laser scanning microscope (CLSM) and transverse microradiography (TMR). Signal intensity (SI), distance between SI peaks (SI-distance) and optical lesion depth were obtained from OCT. Lesion depth was measured from CLSM; lesion depth (LD_TMR) and mineral loss (ML) were obtained from TMR. In vitro root caries under wet and dry conditions showed different OCT images and SI patterns. Lesion depth of OCT and that of CLSM, SI-distance and LD_TMR, LD_TMR and ML significantly correlated. Under dry conditions, half natural root caries showed similar OCT images and SI patterns as in vitro root caries. The base of demineralized dentin could be detected more clearly under dry conditions than under wet conditions.

Root caries: a periodontal perspective

BACKGROUND AND OBJECTIVE

A prevailing dental problem in the periodontal patient is root caries. Specifically, periodontal involvement often results in root surfaces becoming exposed and at risk for this condition. Periodontal therapy often leads to increased gingival recession as well, and the associated increased root caries risk may compromise the long-term success and survival of periodontally treated teeth.This narrative review will address the topic of root caries in the periodontal patient, focusing on unmet research needs.

MATERIAL AND METHODS

The Medline database was searched to identify items dealing with root caries, in terms of clinical features, diagnosis, pathogenic mechanisms and histopathology, as well as epidemiology, focusing then on the relationship between root caries and periodontal disorders.

RESULTS

Although there is extensive literature on root caries, consensus is lacking regarding certain aspects, such as diagnostic criteria, prevalence within populations and indisputable risk factors. Advancing age could be an aggravating factor in susceptibility to root caries for the periodontal patient; however, definitive evidence in this regard is still missing. Similarly, full awareness of the increased risk of root caries in patients with periodontal disease or long-term periodontal treatment appears to be still lacking.

CONCLUSION

Research regarding root caries in age-specific (elderly) periodontal patients is needed. Improved oral hygiene practices, locally applied preventive measures, good dietary habits and regular dental check-ups are crucial approaches to prevent both periodontal disease progression and root caries. Periodontal patients with root exposure should follow a strict root caries prevention protocol, as an integral component of their periodontal maintenance therapy.

A fiber-optic setup for quantification of root surface demineralization

A fiber-optic fluorescence observation (FOFO) technique has been developed for the quantification of demineralized root dentin. The method was tested on 40 specimens of in vitro demineralized parts of human root dentin. Fluorescein sodium salt was used as a penetrating dye. The fluorescein sodium salt was excited using light around 465 nm. The fluorescence signal around 527 nm measured for demineralized dentin was corrected for lamp output and then divided by the corrected fluorescence signal for the sound control dentin on the same root, resulting in a FOFO-value. FOFO-values correlate linearly (r = 0.91) with mineral loss measured by transverse microradiography. Therefore, it was concluded that the FOFO-technique provides a good, non-destructive measure of the severeness of in vitro demineralized human root dentin, and is applicable on bulk dentin. Future work on natural lesions in vivo will be needed to investigate the applicability of the technique in a clinical situation.

Risk factors for and the prevention of root caries in older adults

With the absolute and relative number of elderly people rising in most countries, it is essential that dental practitioners be knowledgeable about the normal changes and disease processes that occur in aging individuals. Especially prevalent in the aging population is root surface caries. Several variables may increase the risk of developing root surface caries. Among these are poor oral hygiene, microbial plaque, periodontal disease, gender (male), coronal caries, dietary habits, xerostomia, low socio-economic status, and infrequent dental visits. While each of these has an effect, plaque seems to have the greatest influence on the susceptibility of teeth to root decay. Improved oral hygiene and regular dental visits, combined with the use of fluoride, may continuously convert active root caries lesions to inactive. In fact, prophylactic programs are more effective in converting active to inactive rather than preventing the development of new lesions. The conscientious dental practitioner must identify his/her older patients at risk for developing root lesions and place a major emphasis on the prevention and treatment thereof.

Hard-tissue substrates for evaluation of cariogenic and anti-cariogenic activity in situ

Hard-tissue substrates include primarily human and bovine enamel and human dentin. They have been used for in situ studies in a natural or sound condition, as well as flattened or containing an in vitro-formed caries-like lesion. Human enamel and dentin are generally the substrates of choice for studies of coronal and root-surface caries, respectively, but bovine enamel appears to offer a suitable alternative for many studies of enamel caries. Substrates with caries-like lesions will respond more rapidly to changes in the intra-oral mineral equilibrium and will allow both demineralization and remineralization to be determined. Findings from some studies suggest that caries-like lesions may respond somewhat differently, depending upon the degree of mineralization of the surface layer. Because in vitro findings with dentin show it to be significantly more soluble in acid than enamel, results from a study that used dentin may not be directly applicable to enamel. Both enamel and dentin substrates can be used in thin-section models. Hard-tissue substrates can also differ, depending upon their intra-oral location. Locations that result in the accumulation of plaque will behave differently from those that are plaque-free. So that plaque would accumulate, substrates have been placed approximally, beneath a fabric or steel mesh, in a protected trough, beneath a metal band or within a depression on the buccal surface. For studies requiring a determination of both demineralization and remineralization, human enamel or dentin containing a surface-softened caries-like lesion and covered with a uniform natural plaque are the substrates of choice.

Human root caries: histopathology of initial lesions in cementum and dentin

The histopathology of human root caries was examined in extracted teeth by different optical methods. The present part of the study details the sequential stages of initial caries in both cementum and peripheral dentin. Significant differences are shown between the mechanisms operating on the various dental hard tissues during development of caries. Histologically distinguishable reaction patterns depended on both the degree of the cariogenic challenge and the respective structural features of cementum and peripheral dentin. Earliest lesions, histologically visible as small clefts traversing cementum and extending into peripheral dentin, were clinically not detectable. Cementum was stepwise destroyed until peripheral dentin became exposed. The exposed peripheral dentin was sclerosed and tubule-free. Demineralization of dentin preceded the degradation of the organic matrix. Frequently, a hypermineralized layer occurred in both cementum and exposed dentin. Its localization was not identical with the anatomical surface. Initial penetration of bacteria into peripheral dentin occurred along small clefts. Breakdown of the organic matrix was the final step in the destructive phase of the carious process.

The effects of 1% pyrophosphate and 0.02% sodium fluoride on artificial caries lesions in vivo

We evaluated the potential of a pyrophosphate-fluoride solution to affect the remineralizing-demineralizing equilibrium, i.e., caries-inhibiting/-promoting effects on enamel in vivo. Fifteen subjects carried dentin blocks and enamel thin sections with artificial caries lesions in removable partial dentures for periods of two weeks, during which time they rinsed twice daily in a double-blind, randomized cross-over design with solutions containing (a) 90 ppm F, (b) 90 ppm F and 1% pyrophosphate, or (c) no active agents (placebo). A severe cariogenic challenge provided to the lesions by plaque under a stainless steel mesh cover resulted in the placebo-treated lesions losing 70.2% +/- 72.1% mineral. The pyrophosphate rinse with fluoride held the mineral loss to only 28.1 +/- 52.8%, while the fluoride rinse without pyrophosphate held the loss to 24.2 +/- 50.1%. The differences between the fluoride and placebo results were significant (p less than 0.01), but the difference between the two fluoride groups was not. A large amount of fluoride was deposited in the dentin lesions. In the surface layer, the concentration was increased from 1000 ppm F to more than 2300 ppm F by both fluoride treatments. The concentration of fluoride in both groups of fluoride-treated lesions further increased to more than 3500 ppm F in the approximate center of the lesion before declining in deeper layers toward the level found in the placebo-treated group. The findings from both mineral change and fluoride uptake phases of this study show that in the presence of 90 ppm F, 1% pyrophosphate did not promote demineralization of artificial caries lesions.

A method of semi-quantitative microradiographic analysis of root surface lesion remineralization

The purpose of this study was to present a modified photometer based digital analysis system for image enhanced microradiographic semi-quantitation of reactions of demineralization and remineralization of root surface lesions. The system was used to determine effects of fluoride on abraded root surface dentin in vitro. Lesions of 30-40 micron depth were produced during 18 h exposure of 180 micron thick single sections in solution of 3 mM Ca (Ca/P 1.67) and 30 mM lactic acid at pH 5.1. Mean mineral content of the lesions was 32% relative to adjacent sound dentin. Exposure of 20 h in the same acid with 5 mM Ca (Ca/P 1.67) and 0.12 mM NaF at pH 6.1 restored the mean mineral content to 76% of normal and increased the resistance of the lesions to demineralization. Remineralization and subsequent demineralization characteristics indicated the growth of fluorapatites on residual minerals in the dentin lesions. The microradiographic analysis system proved to be sensitive and critical in these studies.

Remineralization by a monofluorophosphate dentifrice in vitro of root dentin softened by artificial caries

Artificial caries-softened dentin lesions in root surfaces were treated with 50% slurries of a monofluorophosphate (MFP) dentifrice or a placebo dentifrice twice daily for ten days. Between dentifrice treatments, the lesions were kept in a remineralizing solution. Both treatments resulted in statistically significant remineralization, with the MFP dentifrice being significantly better than the placebo. Deposition of new mineral from the MFP dentifrice occurred about equally at or within the surface zone and at the deepest part of the lesion. Mineral deposition from the placebo appeared to be more uniformly distributed within the lesion.