Effect of Fixed Metallic Oral Appliances on Oral Health

Oral Galvanism Side Effects: Comparing Alloy Ions and Galvanic Current Effects on the Mucosa-like Model

The interaction of different dental alloys with the oral environment may cause severe side effects (e.g., burning sensation, inflammatory reactions, carcinogenesis) as a result of oral galvanism. However, the pathogenesis of side effects associated with oral galvanism is still unclear, and the effects of direct current and alloy corrosion ions are considered potentially contributing factors. Therefore, the aim of this study was to systemically compare the damaging effects of (1) galvanism as a synergistic process (direct current + corrosion ions), (2) direct current separately, and (3) corrosion ions separately on an in vitro mucosa-like model based on a cell line of immortalized human keratinocytes (HaCaTs) to reveal the factors playing a pivotal role in dental alloys side effects. For this, we chose and compared the dental alloys with the highest risk of oral galvanism: Ti64-AgPd and NiCr-AgPd. We showed that galvanic current may be the leading damaging factor in the cytotoxic processes associated with galvanic coupling of metallic intraoral appliances in the oral cavity, especially in the short-term period (28 days). However, the contribution of corrosion ions (Ni2+) to the synergistic toxicity was also shown, and quite possibly, in the long term, it could be no less dangerous.

The Impact of Commercially Available Dry Mouth Products on the Corrosion Resistance of Common Dental Alloys

Dental implants are thought to be implanted for life, but throughout their lifespan, they function in aggressive oral environment, resulting in corrosion of the material itself as well as possible inflammation of adjacent tissues. Therefore, materials and oral products for people with metallic intraoral appliances must be chosen carefully. The purpose of this study was to investigate the corrosion behavior of common titanium and cobalt-chromium alloys in interaction with various dry mouth products using electrochemical impedance spectroscopy (EIS). The study showed that different dry mouth products lead to different open circuit potentials, corrosion voltages, and currents. The corrosion potentials of Ti64 and CoCr ranged from -0.3 to 0 V and -0.67 to 0.7 V, respectively. In contrast to titanium, pitting corrosion was observed for the cobalt-chromium alloy, leading to the release of Co and Cr ions. Based on the results, it can be argued that the commercially available dry mouth remedies are more favorable for dental alloys in terms of corrosion compared to Fusayama Meyer's artificial saliva. Thus, to prevent undesirable interactions, the individual characteristics of not only the composition of each patient's tooth and jaw structure, but also the materials already used in their oral cavity and oral hygiene products, must be taken into account.

Use of liquid-based cytology samples reveals genomic instability and cell death in patients undergoing orthodontic treatment

PURPOSE

To examine the use of liquid-based exfoliative cytology to determine the presence of genomic instability and cell death in the oral mucosa of patients with orthodontic appliances.

METHODS

Fifty-four oral mucosa samples were collected from 18 patients and divided into three stages: T0, before fixation of orthodontic appliances; T1, 25 days after appliance fixation; T2, 90 days after appliance fixation. All samples were Papanicolaou-stained and observed by microscopy (1,000 cells/sample) to ascertain the frequency of micronucleated cells (MN) and nuclear abnormalities (nuclear buds (NB), binucleated (BN), condensed chromatin (CC), karyorrhexis (KR), and karyolysis (KL)). Differences were analyzed statistically using the Mann-Whitney, Wilcoxon, Kruskal-Wallis and chi-squared tests.

RESULTS

After placement of orthodontic appliances, significant differences were observed for genomic instability biomarkers (MN and NB) and cell death (CC, KR and KL) (P < 0.05). Female patients and older patients exhibited a higher frequency of MN.

CONCLUSION

Liquid-based cytology has revealed that orthodontic appliances induce genomic instability and cell death in epithelial tissue of the oral mucosa, facilitating sample preservation and yielding more than one preparation per sample. Future studies should investigate whether such cell damage can be reversed through cell repair or whether cell alterations evolve and lead to disease.

Minimization of Adverse Effects Associated with Dental Alloys

Metal alloys are one of the most popular materials used in current dental practice. In the oral cavity, metal structures are exposed to various mechanical and chemical factors. Consequently, metal ions are released into the oral fluid, which may negatively affect the surrounding tissues and even internal organs. Adverse effects associated with metallic oral appliances may have various local and systemic manifestations, such as mouth burning, potentially malignant oral lesions, and local or systemic hypersensitivity. However, clear diagnostic criteria and treatment guidelines for adverse effects associated with dental alloys have not been developed yet. The present comprehensive literature review aims (1) to summarize the current information related to possible side effects of metallic oral appliances; (2) to analyze the risk factors aggravating the negative effects of dental alloys; and (3) to develop recommendations for diagnosis, management, and prevention of pathological conditions associated with metallic oral appliances.

Periodontal clinico-morphological changes in patients wearing old nickel-chromium and copper alloys bridges

Elderly population frequently presents more than one prosthetic restoration realized from different types of dental alloys which, in time, suffer various alterations in the oral environment. Metallic ions are released in saliva due to its electrolytic qualities, interacting with the contact tissues. Studies regarding cytotoxicity of dental alloys are providing contradictory results. Besides biocompatibility, the microbial factor is also greatly influencing the long-term success of the prosthetic rehabilitation. This study's aim was to assess the response of the gingival tissue to nickel-chromium (Ni-Cr) and copper (Cu)-based dental casting alloys from fixed dentures present in many patients from Romania. Gingival samples were taken from 124 patients wearing fixed dental restorations made from these two types of alloys from injured areas surrounding the abutment teeth; histological specimens were prepared, fixed in 10% neutral buffered formalin, paraffin-embedded and stained with Hematoxylin-Eosin (HE). Histological analysis showed the existence of a chronic inflammatory infiltrate in the gingival chorion, necrosis areas, and vascular congestion. Various morphological alterations appeared, depending on the intensity of the inflammation and the immune response. The surface epithelium suffered a hyperplasic reaction, either limited to acanthosis or involving the whole epithelium, the release of the Cu(2+) and Ni(2+) ions from the dental alloys used in bridges and crowns being responsible for inducing gingival hyperplasia and a chronic inflammation in the areas situated around the abutment teeth. The immunohistochemical study allowed us to observe an increased number of positive cluster of differentiation 3 (CD3) T-lymphocytes in periodontium, proving that the cellular immune response is rapid and intense.

Relationship between Fixed Dental Crowns and Volatile Sulphur Compounds

Objectives: The aim of this study was to investigate and compare the level of halitosis in patients with/without fixed crowns and in addition the influence of various crown parameters on halitosis was also explored. Methods: In total, 96 subjects (fixed crowns = 52; no crowns = 44) participated in the study. The levels volatile sulphur compounds (VSCs) of hydrogen sulphide (H2S), methyl mercaptan (CH3SH), and dimethyl sulphide (CH3SCH3) were evaluated with breath samples using gas chromatography and used for classification as presence or absence of halitosis. The periodontal clinical parameters for all the participants as well as the crown parameters for participants with fixed crowns were also evaluated. Cross tabulation, Chi-square test, and one-way analysis of variance tests were used for the statistical analysis and comparisons. Results: Breath samples revealed, 50 (52.1%) participants were suffering from halitosis. Out of VSCs, the level of CH3SCH3 (62.5%) was found to be the most prevalent. Significant correlations were observed between the presence of fixed crowns and oral halitosis (p < 0.001). Statistically significant difference in the concentration of H2S and CH3SH (p < 0.001) and no significance for CH3SCH3 (p = 0.075) between patients with/without fixed crowns was found. The presence of halitosis was more prevalent in the subjects with crown parameters (subgingival margin, over-contoured margin, open-crown margin, over-contoured and under-contoured crowns) considered clinically defective/unacceptable (p < 0.05). Conclusions: Presence of fixed dental crowns significantly contributes to the oral halitosis. Dental crowns with defects significantly impair the hygienic conditions and oral microflora resulting in high prevalence of halitosis.