An animal model of intrinsic dental erosion caused by gastro-oesophageal reflux disease

Onset and progression of dental erosion in a mouse model

OBJECTIVE

Purpose of this research was to examine the onset, progression and wear rates of dental erosion in an established mouse model.

MATERIAL AND METHODS

Dental erosion in mice was experimentally induced, and the acidic effects of cola drink on their teeth after 2, 4 and 6-weeks were closely analysed by scanning electron microscopy. The tooth height and enamel or dentin loss were established.  Results: The dental erosion on the molars showed clear progression from 2 to 6 weeks. By the 2-week mark, a significant portion of enamel was already eroded, revealing the dentin on the lingual cusps. When adjusted for attritional wear, molars exposed to cola for 2 weeks showed a 35% drop in lingual tooth height compared to controls (533 μm vs. 818 μm). At 4 and 6 weeks, the cola-exposed group continued to display decreased lingual tooth heights by 40% (476 μm vs. 799 μm) and 43% (440 μm vs. 767 μm), respectively.

CONCLUSION

This study revealed significant acidic effects of cola drink on mouse molars as early as 2 weeks. These findings highlight the challenge of monitoring dental erosion clinically and underscore the importance of early preventive and intervention measures.

Identifying causal relationships between gastroesophageal reflux and extraesophageal diseases: A Mendelian randomization study

Traditional observational and in vivo studies have suggested an etiological link between gastroesophageal reflux disease (GERD) and the development of extraesophageal diseases (EEDs), such as noncardiac chest pain. However, evidence demonstrating potential causal relationships is lacking. This study evaluated the potential causal relationship between GERD and EEDs, including throat and chest pain, asthma, bronchitis, chronic rhinitis, nasopharyngitis and pharyngitis, gingivitis and periodontal disease, cough, using multiple Mendelian randomization (MR) methods, and sensitivity analysis was performed. The Mendelian randomization Pleiotropy RESidual Sum and Outlier and PhenoScanner tools were used to further check for heterogeneous results and remove outliers. MR with inverse-variance weighted (IVW) showed a significant causal relationship between GERD and EEDs after Bonferroni correction. IVW results indicated that GERD increased the risk of chronic rhinitis, nasopharyngitis and pharyngitis (odds ratio [OR] = 1.482, 95% confidence interval [CI] = 1.267-1.734, P < .001], gingivitis and periodontal disease (OR = 1.166, 95% CI = 1.046-1.190, P = .001), throat and chest pain (OR = 1.585, 95% CI = 1.455-1.726, P < .001), asthma (OR = 1.539, 95% CI = 1.379-1.717, P < .001), and bronchitis (OR = 1.249, 95% CI = 1.168-1.335, P < .001). Sensitivity analysis did not detect pleiotropy. Leave-one-out analysis shows that MR results were not affected by individual single nucleotide polymorphisms. The funnel plot considers the genetic instrumental variables to be almost symmetrically distributed. This MR supports a causal relationship among GERD and EEDs. Precise moderation based on causality and active promotion of collaboration among multidisciplinary physicians ensure high-quality diagnostic and treatment recommendations and maximize patient benefit.

Dentoalveolar Alterations in an Adenine-Induced Chronic Kidney Disease Mouse Model

Chronic kidney disease (CKD) is characterized by kidney damage and loss of renal function. CKD mineral and bone disorder (CKD-MBD) describes the dysregulation of mineral homeostasis, including hyperphosphatemia and elevated parathyroid hormone (PTH) secretion, skeletal abnormalities, and vascular calcification. CKD-MBD impacts the oral cavity, with effects including salivary gland dysfunction, enamel hypoplasia and damage, increased dentin formation, decreased pulp volume, pulp calcifications, and altered jaw bones, contributing to clinical manifestations of periodontal disease and tooth loss. Underlying mechanisms are not fully understood, and CKD mouse models commonly require invasive procedures with high rates of infection and mortality. We aimed to characterize the dentoalveolar effects of an adenine diet (AD)-induced CKD (AD-CKD) mouse model. Eight-week-old C57BL/6J mice were provided either a normal phosphorus diet control (CTR) or adenine and high-phosphorus diet CKD to induce kidney failure. Mice were euthanized at 15 weeks old, and mandibles were collected for micro-computed tomography and histology. CKD mice exhibited kidney failure, hyperphosphatemia, and hyperparathyroidism in association with porous cortical bone in femurs. CKD mice showed a 30% decrease in molar enamel volume compared to CTR mice. Enamel wear was associated with reduced ductal components, ectopic calcifications, and altered osteopontin (OPN) deposition in submandibular salivary glands of CKD mice. Molar cusps in CKD mice were flattened, exposing dentin. Molar dentin/cementum volume increased 7% in CKD mice and pulp volume decreased. Histology revealed excessive reactionary dentin and altered pulp-dentin extracellular matrix proteins, including increased OPN. Mandibular bone volume fraction decreased 12% and bone mineral density decreased 9% in CKD versus CTR mice. Alveolar bone in CKD mice exhibited increased tissue-nonspecific alkaline phosphatase localization, OPN deposition, and greater osteoclast numbers. AD-CKD recapitulated key aspects reported in CKD patients and revealed new insights into CKD-associated oral defects. This model has potential for studying mechanisms of dentoalveolar defects or therapeutic interventions. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Genetic Aspects of Dental Erosive Wear and Dental Caries

Objectives

The present review aims to give an overview of the literature focusing on novel genetic aspects of dental erosion and dental caries. Once the tooth erupts into the oral cavity, the regenerative capability of enamel is fundamentally limited due to the loss of dental epithelium during eruption. The susceptibility or resistance to dental erosion and caries is presumably a result of environmental, phenotypic, and/or genetic influence. Even though it is evident that individuals frequently exposing their teeth to acid and sugar are at high risk of developing dental erosion and caries, the findings exclusively based on these factors are elusive. Data resources and study selection. The present review was based on data collected from the National Library of Medicine database with different combinations of the following terms: "tooth," "dental," "dentin," "enamel," "erosion," "erosive wear," "caries," "decay," "gene," and "genetic." A total of forty-six studies met the inclusion criteria. Data were extracted by one reviewer and verified by another.

Conclusion

The high prevalence of erosion and caries among certain groups, and observations that not all individuals appearing to be at risk develop these lesions, has sparked research on identifying genetic effects to these conditions. A connection of genome-wide and candidate gene studies has increased considerably in the literature. This review reveals largely varying success among studies, demonstrating the difficulties of developing the study with adequate sample sizes and durable phenotype definitions that permit enough statistical power to identify genetic contributors.

Reflux and dental disorders in the pediatric population: A systematic review

OBJECTIVES

To investigate the role of laryngopharyngeal reflux (LPR) or gastroesophageal reflux disease (GERD) in the development of dental disorders in pediatric population.

METHODS

PubMed, Scopus Cochrane database were assessed for subject headings using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) recommendations. Relevant studies published between January 1990 and January 2020 describing the association between reflux and dental disorders in children were retrieved. Three authors reviewed the LPR diagnosis method; inclusion criteria and outcomes. The bias analysis was performed through the tools of the Oxford Centre for Evidence-Based Medicine evidence levels.

RESULTS

The electronic search identified 126 publications, of which 11 clinical studies and 2 basic science researches met our inclusion criteria. There is an important heterogeneity between studies about diagnostic method and clinical outcome evaluation. All studies based the reflux diagnosis on GERD criteria. No author considered hypopharyngeal nonacid reflux episodes through hypopharyngeal-esophageal intraluminal multichannel impedance pH monitoring (HEMII-pH). The results of studies support a higher prevalence of dental erosion in children with GERD compared with healthy individuals. Controversial findings were found about the potential association between reflux and caries, and the modification of both saliva composition and production in reflux children.

CONCLUSION

The association between reflux and dental disorder is still uncertain. Future studies considering pharyngeal acid and nonacid reflux episodes through HEMII-pH are needed to confirm this hypothesis. The pepsin detection in saliva would be an additional way for detecting LPR in children with dental disorders.

Laryngopharyngeal reflux, gastroesophageal reflux and dental disorders: A systematic review

OBJECTIVES

To investigate the role of gastroesophageal reflux disease (GERD) and laryngopharyngeal reflux (LPR) in the development of dental disorders.

METHODS

The first outcome was review of the role of reflux in the development of dental disorders in adults. The second outcome was review of the potential pathophysiological mechanisms underlying the association between reflux and dental disorders. Three investigators screened publications for eligibility and exclusion based on predetermined criteria through a literature search conducted on PubMed, Cochrane Library, and Scopus according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

From 386 publications, 24 studies were kept for analysis. Objective approaches were used in 16 studies to confirm GERD diagnosis. Pharyngeal reflux episodes (LPR) were considered in 2 studies. No study considered nonacid reflux. The study results supported a higher prevalence of dental erosion and caries in reflux patients compared with healthy individuals. Patients with dental erosion have a higher prevalence of reflux than controls. The pathophysiological mechanisms would involve changes in the saliva physiology. No study investigated the microbiota modifications related to reflux although the findings are supporting the critical role of microbiota change in the development of dental disorders. There is an important heterogeneity between studies about diagnostic methods and clinical outcome evaluation.

CONCLUSION

The involvement of reflux in the development of dental disorders is not formally demonstrated and requires future investigations considering pharyngeal acid and nonacid reflux episodes and in particular their potential impact on oral microbiota.

Dental erosion in mice with impaired salivary gland function

Objective: Salivary flow rate exerts an essential impact on the development and progression of dental erosion. In this work, the experimental dental erosion in non-obese diabetic (NOD) mice with reduced salivary flow rate was induced, and the erosive effect of acidic drinks on their dentition was studied.Material and methods: Three acidic drinks (sports drink, cola light drink and sugar containing cola drink) were given to adult NOD mice (groups: N = 11) as the only drink for 6 weeks. Two control groups were included; wild type and NOD control (groups: N = 9). Experimental and control (water) teeth were dissected out and observed by scanning electron microscopy (SEM). Mandibular first molars were subsequently embedded in Epon, ground transversely, observed again by SEM, and the enamel thickness and tooth height were measured.Results: Mandibular molars were considerably more eroded than maxillary molars. The erosive process started at the top of the cusps and subsequently extended in the cervical, mesio-distal, and pulpal direction. Erosive lesions were evident in increased succession from sports drink, cola light to cola drink exposed mandibular molars, with the lingual tooth height being approximately 23%, 26%, and 37% lower, respectively, compared to the control. The lingual enamel was approximately 48% thinner in sports drink molars and 62% thinner in cola light molars. In cola drink molars, the lingual enamel was totally eroded, and significant erosion of dentine was evident.Conclusion: Reduced salivary flow, together with a high consumption of acidic drinks, results in severe erosion of NOD mice molars.

New animal model of extrinsic dental erosion-Erosive effect on the mouse molar teeth

OBJECTIVE

Consumption of acidic food and drinks is considered as important risk factor for development of dental erosion. There are several in vitro and in situ studies focusing on the risk indicators and preventive treatment, however, the need for a standardized animal model has been emphasised for many years. The aim was to establish an animal model of extrinsic dental erosion, which may serve as a standard for future studies to improve our understanding of the erosion.

DESIGN

Two acidic drinks, sports drink and cola drink, were given to young mice for six weeks. Experimental and control (water) molars and incisors were dissected out and observed by scanning electron microscopy (SEM). Mandibular first molars were subsequently ground transversely and observed again by SEM. The tooth height and enamel thickness were measured on the SEM images.

RESULTS

The lingual surface of the mandibular molars was most eroded after consumption of acidic drinks. The cola drink exhibited higher erosive effect on mandibular molars compared to sports drink. The lingual tooth height, compared to control, was about 34% and 18% lower in the cola drink and sports drink molars, respectively. Compared to the control molars, the lingual enamel was about 23% thinner in the sports drink molars and totally eroded on the certain lingual areas of the cola drink molars.

CONCLUSIONS

This new animal model of extrinsic dental erosion and the presented method with ground molars observed in SEM are suitable for further studies, which will gain deeper insights into the erosive disease.

Efficacy of different strategies to treat root dentin eroded by liquid or gaseous hydrochloric acid associated with brushing abrasion

OBJECTIVE

This study aims to evaluate how casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) associated with Nd:YAG or Diode laser affects dentin exposed to hydrochloric acid (HCl) with or without tooth brushing.

DESIGN

One hundred and sixty human root dentin blocks were selected after they were initially eroded with liquid HCl (pH 1.2) 3x for one day. The blocks were divided into the following groups: G1- liquid HCl (HCl-l), G2- HCl-l + brushing, G3- gaseous HCl (HCl-g), and G4- HCl-g + brushing. Each group was randomly assigned to the following treatments (n = 10): A) Control (no treatment), B) CPP-ACP, C) CPP-ACP associated with Nd:YAG laser (λ = 1064 nm) (40 mJ, 10 Hz, 0.4 W, 15 s), and D) CPP-ACP associated with Diode laser (λ = 980 nm) (0.5 W, 200 μs, 15 s). The treatment with CPP-ACP (G2, G3 and G4) was applied on the dentine surface for 5 min. Erosion (6x/day/20 s) and erosion (6x/day/20 s) with abrasion (2x/10 s) were performed for five days. Dentin volume loss was determined by 3D confocal laser microscopy. Data were analyzed with two-way ANOVA and Tukey's tests.

RESULTS

G1 - CPP-ACP (10.77 ± 1.66) and CPP-ACP associated with Diode laser (9.98 ± 0.89) showed lower volume loss in relation Control group (12.86 ± 0.63) (p < 0.05). G2 - CPP-ACP associated with Diode laser (12.41 ± 1.08) elicited lower volume loss as compared to the Control (14.42 ± 1.24) (p < 0.05). As for G3 and G4, all treatments showed similar volume loss.

CONCLUSION

CPP-ACP and CPP-ACP associated with Diode laser could control dental tissue loss in dentin eroded by liquid HCl. Moreover, CPP-ACP associated with Diode laser could effectively decrease dental tissue loss in dentin exposed to liquid HCl and brushing.

Dental and oropharyngeal lesions in rats with chronic acid reflux esophagitis

OBJECTIVE

In this study, we evaluated pathological changes in the tooth and pharynx of GERD rats to elucidate the association between gastric acid reflux and oral and pharyngeal diseases.

METHODS

An experimental rat model of chronic acid reflux esophagitis was surgically created. The oral cavities were observed histologically every 2 weeks until 20 weeks after surgery.

RESULTS

At 10 weeks after surgery, molar crown heights in GERD rats were shorter than that in control rats, and inflammatory cell infiltration by gastric acid reflux was found in the periodontal mucosa of GERD rats. Furthermore, dental erosion progressed in GERD rats at 20 weeks after surgery, and enamel erosion and dentin exposure were observed. During the same period, inflammatory cell infiltration was observed in the mucosa of the posterior part of the tongue. These findings suggest that gastric acid reflux may be one of the exacerbating factors of dental erosion, periodontitis and glossitis.

CONCLUSION

We investigated oral changes in an experimental rat model of GERD and observed development of dental erosion, periodontitis and glossitis. Our findings suggested chronic gastric acid reflux may be involved in the pathogenesis of oral disease.

Susceptibility of partially desalivated rats to erosive tooth wear by calcium-supplemented beverages

OBJECTIVES

To investigate the susceptibility of partially desalivated rats to erosive tooth wear (ETW); the anti-erosive effect of a calcium-supplemented beverage; and the quantification of ETW by microcomputed tomography (micro-CT).

METHODS

The study population consisted of thirty-eight rats, divided into partially desalivated (n = 19) and normal salivary flow (n = 19). They were randomly allocated into three subgroups (n = 6-7): A-diet soda, B-diet soda + calcium, C-water (control). Solutions were provided ad libitum for 28 days, and the rats were euthanized afterwards. Each left hemi-mandible was scanned using micro-CT for enamel volume (three molars) calculation. Visual analysis of photographs of the lingual surface of first molars was performed independently by three blinded examiners. Data were statistically analysed (α = .05).

RESULTS

Micro-CT revealed no significant differences between partially desalivated or normal groups. Rats consuming A had more enamel loss than those consuming B or C, which did not differ from each other. For visual analysis, desalivation did not affect ETW. Rats consuming C showed the lowest ETW, followed by B and then A, for both partially desalivated and normal rats. Spearman correlation between the two ETW quantification methods was -.65.

CONCLUSIONS

Partial desalivation did not increase ETW. Ca-containing beverage prevented ETW. Micro-CT quantified ETW, although it was not as sensitive as visual analysis.

Dentin hypersensitivity induces anxiety and increases corticosterone serum levels in rats

AIMS

Investigate the relationships between experimentally induced dentin hypersensitivity (DH) with behavioral, endocrine and dentin erosion data.

METHODS

Male Wistar rats divided into four groups, two controls and two experimental, received tap water or isotonic solution (Gatorade®, lemon, pH2.7) for 30 or 45 days. The DH test was performed by a cold water stimulus on molars. A score (0-3) was given to the rats' pain response. Anxiety was evaluated by the elevated plus maze model and by serum corticosterone levels. The dentin erosion was observed by scanning electron microscopy (SEM). Anatomopathological studies were performed on the stomach, adrenal, kidney, and liver.

RESULTS

Relative to control groups, experimental rats showed: 1) increased hypersensitivity scores (control group, 0; experimental groups, 2 (limits 0.5-3) on the 30th day and 2 (limits 1-3) on the 45th day); 2) reduced percentage of time and entries in the open arms and in serum corticosterone levels; 3) totally exposed dentinal tubules on the 30th day in SEM analysis of the teeth; and 4) no alterations in the anatomopathological and histological evaluations.

CONCLUSIONS

The treatment with isotonic solution for 30 days was able to induce DH after erosive challenge and severe DH was observed after isotonic solution treatment for 45 days. The pain induced by cold stimuli was consistent with the grade of DH. The close relationships between dental erosion, response to pain, serum levels of corticosterone and the EPM behavior responses reveal the effects of DH at several levels.

Oral manifestations of gastroesophageal reflux disease

Numerous case-control and other studies involving confirmation of gastroesophageal reflux disease (GERD) by esophageal pH-metry and the assessment of dental erosions have shown significant associations between the two conditions in both adults and children. By contrast, when asked to vote on whether GERD may cause dental erosions, only 42% of physicians strongly agreed that such an association existed in adults, and just 12.5% strongly agreed for children, respectively in two global consensus reports. Part of this divergence between the perceptions of physicians and the findings of research publications may reflect a general lack of oral health education during medical training, and cursory oral examinations being made under less-than-ideal conditions. Adequate salivary secretions are essential for the protection of the teeth and the oropharyngeal and esophageal mucosa. The quantity and quality of the saliva require monitoring as many drugs, including several of the proton pump inhibitors (PPIs), can cause hyposalivation. In addition, PPIs do not always result in adequate acid suppression. Therefore, collaboration between physicians and dentists is strongly advocated to prevent or ameliorate possible adverse oral effects from both endogenous and exogenous acids, and to promote adequate saliva production in patients with GERD.

Gastroesophageal reflux disease and tooth erosion

The increasing prevalence of gastroesophageal reflux disease (GERD) in children and adults, and of “silent refluxers” in particular, increases the responsibility of dentists to be alert to this potentially severe condition when observing unexplained instances of tooth erosion. Although gastroesophageal reflux is a normal physiologic occurrence, excessive gastric and duodenal regurgitation combined with a decrease in normal protective mechanisms, including an adequate production of saliva, may result in many esophageal and extraesophageal adverse conditions. Sleep-related GERD is particularly insidious as the supine position enhances the proximal migration of gastric contents, and normal saliva production is much reduced. Gastric acid will displace saliva easily from tooth surfaces, and proteolytic pepsin will remove protective dental pellicle. Though increasing evidence of associations between GERD and tooth erosion has been shown in both animal and human studies, relatively few clinical studies have been carried out under controlled trial conditions. Suspicion of an endogenous source of acid being associated with observed tooth erosion requires medical referral and management of the patient as the primary method for its prevention and control.

Histological examination of the relationship between respiratory disorders and repetitive microaspiration using a rat gastro-duodenal contents reflux model

Microaspiration due to gastroesophageal reflux (GER) has been suggested as a factor contributing to the development and exacerbation of several respiratory disorders. To explore the relationship between GER and respiratory disorders, we histologically examined the bilateral lungs of a rat gastroduodenal contents reflux model, which was previously used to investigate the histogenesis of Barrett's esophagus and esophageal carcinoma. GER was surgically induced in male Wistar rats. The bilateral lungs of the reflux rats were examined with hematoxylin and eosin (HE), PAS-Alcian blue, and Azan staining at 10 and 20 weeks after surgery. Immunohistochemical staining of CD68 and α-SMA was also performed. Aspiration pneumonia with severe peribronchiolar neutrophilic and lymphocytic infiltrates, goblet cell hyperplasia, prominence of blood vessels, and increased thickness of the smooth muscle layer were detected. Bronchiolitis obliterans (BO)-like lesions comprising granulation tissue with macrophages, spindle cells, and multinucleated giant cells in the lumen of respiratory bronchioles were observed in the bilateral lungs of the reflux animals. These findings suggest that the severe inflammation and the BO-like lesions may play a role in exacerbation of the forced expiratory volume in 1 second (FEV 1) in human cases. In conclusion, we speculate that repetitive microaspiration due to GER may contribute to the exacerbation of various respiratory diseases, particularly asthma and chronic obstructive pulmonary disease (COPD), and the development of BO syndrome following lung transplantation. The reflux model is a good tool for examining the causal relationships between GER and respiratory disorders.

Relationship between dental erosion and respiratory symptoms in patients with gastro-oesophageal reflux disease

OBJECTIVES

Both dental erosion and respiratory symptoms are extra-oesophageal manifestations of gastro-oesophageal reflux disease (GERD). The aim of this study was to determine whether dental erosion was correlated with respiratory symptoms in GERD patients.

METHODS

88 GERD patients were recruited and assigned to three groups mainly according to the frequency of respiratory symptoms: Group I: never; Group II: occasional (1-2 days a week or less); Group III: frequent (3-5 days a week or more). All patients underwent medical evaluations, including medical history, questionnaire answering and alimentary tract examinations. Dental examinations were carried out on these patients and 36 healthy controls. Dental erosions were measured by modified method of Smith and Knight Tooth Wear Index (TWI). Location and severity of dental erosion were recorded.

RESULTS

The prevalence of dental erosion in Group III (64.52%) was higher (p<0.05) than that in Groups I (36.67%) and II (44.44%). GERD patients were presented with dental erosion with TWI scores ranging from 1 to 4. Though proportion of dental erosion with Score 2 (7/20) in Group III was higher than that in Group I (2/11) and Group II (3/12), there was no statistical significance in the proportions of erosion scores among three patient groups. Correlation coefficient between airway symptoms and scores of dental erosion was 0.231 (p<0.05). Palatal erosion of upper incisor was seen in 8 persons (72.7%) in Group I, 9 persons (75%) in Group II and 16 persons (80%) in Group III (p>0.05). Labial erosion of upper incisors was found in 1 person in Groups I and II respectively and 4 persons in Group III. All patients with labial erosion on upper incisors had palatal erosion, except 1 patient in Group III.

CONCLUSIONS

In GERD patients, dental erosions are more prevalent in patients with frequent respiratory symptoms than those in patients with occasional and without respiratory symptoms. Palatal erosion of upper incisor is the main manifestation in patients. Acid reflux is the main causative factor of dental erosion in GERD patients with airway symptoms.