Current Issues in Oral Health: Introduction to the Special Issue

1. Introduction

This Special Issue of Oral exemplifies a broad range of problems in oral health and the delivery of oral healthcare, ranging from treating the fear of dental care to the detection of oral lesions by artificial intelligence. Below, we briefly introduce each of the contributions to this Issue, while reminding ourselves of the Bangkok Declaration of the World Health Organization in 2024 on the significant health challenges of oral diseases as they impact the well-being of individuals, families and communities [1].

2. Periodontitis and Alzheimer’s Disease

Lundergan et al. [2] discuss evidence from studies on humans and animals, as well as therapeutic interventions, to understand the link between periodontitis and Alzheimer’s disease. The studies of Kaye et al. [3], Gil-Montoya et al. [4], Ide et al. [5] and Iwasaki et al. [6] have indicated an association between periodontal disease and cognitive decline. In a randomized controlled trial, Chen et al. [7] showed that oral health intervention slowed cognitive decline in patients with mild Alzheimer’s disease. A study in rats showed that occlusal rehabilitation following long-term tooth loss resulted in improved spatial memory and increased neuron density in the hippocampus compared to the group with unrestored tooth loss [8]. Wang et al. [9] propose that masticatory dysfunction leads to reduced cerebral blood flow and reduced stimulation of peripheral receptors; changes in neural pathways and neurodegeneration, with tooth loss aggravating existing neurodegenerative changes; and long-term inflammatory stress, leading to damage to the central nervous system [9]. The authors suggest that the use of NLRP3 inflammasome inhibitors could be effective in the future treatment of both periodontitis and Alzheimer’s disease, since this “organelle” can facilitate osteoclast activity in periodontitis and neuronal cell death in Alzheimer’s disease [2].

3. Treatment of Dental Fear

It is estimated that fear of dental treatment afflicts more than 30% of the world population [10]. Cognitive behavioral therapy and behavioral therapy have been shown to result in a significant reduction in dental anxiety, although the results were considered to be based on a “low quality of evidence” [11]. Behavioral therapies seemed to improve patients’ acceptance of dental treatment more than general anaesthesia did [12]. Using focus groups, Daly et al. [13] investigated the experiences of allied dental professionals in treating patients with dental fear and their receptivity to a stepped-care approach. They established that a stepped-care approach to dental fear treatment may be useful in meeting the needs of patients and dental professionals, and identified the potential of collaborations between dental health and mental health professionals.

4. Detecting Mucosal Lesions with Artificial Intelligence

Although the diagnosis of elementary white mucosal lesions constitute just 5% of oral pathologies, lesions including leukoplakia and lichen planus can lead to malignancies, and thus a highly reliable diagnostic approach is extremely desirable [14]. White mucosal lesions include frictional hyperkeratosis (characterized by epithelial thickening resulting from chronic irritation), oral leukoplakia (manifesting as a white patch resulting from tobacco or alcohol use), oral lichen planus (a chronic disorder thought to be immune-mediated), oral lichenoid reactions (resulting from medications or dental materials), oral condylomas and papillomas (lesions arising from human papilloma virus infection), and oral candidiasis, or thrush [15,16,17,18,19,20]. In general, only senior oral medicine experts reliably distinguish these lesions. La Mantia et al. [21] used a dataset of photographs of different elementary white mucosal oral lesions and trained an artificial intelligence platform to then evaluate its ability to diagnose the lesions. The system was able to correctly identify 77% of the lesions.

5. Doubts on the Use of Chelating Gels in Endodontics

Aqueous solutions of ethylenediaminetetraacetic acid (EDTA) were introduced by Nygaard-Ostby in 1957 to help clean dentin and widen root canals [22]. EDTA liquids and gels both lubricate the canals and remove the smear layer [23,24], but gels are recommended in the early stages of preparation where they provide a “glide path” in canals that are challenging [23]. Wright et al. [25] found that among members of the Australian Society of Endodontology, most endodontics residents (86%) and endodontists (75%) never or rarely used gels, raising doubts about its clinical necessity.

6. Loss of Enamel Volume Following Exposure to Energy Drinks

A high consumption of energy drinks can result in cardiovascular problems, including atrial and ventricular arrhythmias, myocardial infarctions, cardiomyopathies, sudden cardiac death, nervous system disorders and the potential for addiction [26,27]. Sugar-sweetened beverages, sport drinks and energy drinks may cause a loss of enamel tooth surface as a result of exposure to acids [28]. Schulze et al. [29] studied the erosive potential of these drinks as a function of their pH and titratable acidity (essentially, the strength of the acid). They concluded that the pH of a drink cannot be the only harmful aspect of a beverage, and that the proprietary components and caffeine content of the beverage may also contribute to enamel loss.

7. Neutrophil Chemotaxis and Glutathione

Extracellular glutathione levels in the periodontium and gingival cervicular fluid are decreased in periodontitis patients [30,31]; additionally, the intracellular ratio of total glutathione to oxidized glutathione (GSH:GSSG ratio) is also low in the neutrophils of periodontitis patients [32]. Neutrophils isolated from the blood of periodontitis patients show aberrant chemotactic behavior [33]. Sham and Grant [34] assessed the effects of glutathione-modulating compounds in neutrophils isolated from healthy donors and found that the perturbation of glutathione homeostasis decreases the chemotaxis of neutrophils. They found a decrease in glutathione and chemotactic ability in peripheral blood neutrophils isolated from periodontitis patients, and a change in the abundance of proteins involved in glutathione homeostasis, suggesting that neutrophils from periodontitis patients are restricted in their ability to deal with oxidative stress and to undergo chemotaxis.

8. Odontogenic Infections and Virulent Prevotella

Odontogenic infections with mixed bacterial species can progress to life-threatening circumstances, particularly by spreading via the fascial planes to cause bacteremia, sepsis, and airway compromise [35,36,37,38]. Treatment involves surgical removal, drainage, and antibiotic administration [38,39]. Describing three clinical cases, Nix et al. [40] indicate that Prevotella species can become virulent during post-extraction wound healing when accompanied by excessive plaque, nearby gingivitis or periodontitis, and in immunocompromised patients, drawing special attention to antibiotic-resistant Prevotella buccae [41,42]. They emphasize the potential need for Metronidazole administration in such cases [43].

9. Treatment of Molar Incisor Hypomineralization

Weerheijm et al. [44] described molar incisor hypomineralization (MIH) in 2001, referring to qualitative developmental enamel defects in permanent first molars and permanent incisors. The prevalence of MIH has been estimated to be between 13.1% and 14.2%. [45,46,47]. Sezer and Çarıkçıoğlu [48] indicate that the mineral content of these teeth can be increased with the use of agents containing casein phosphopeptide amorphous calcium phosphate [49], casein phosphopeptide amorphous calcium fluoride phosphate [50], fluoride and calcium glycerophosphate [51].

10. Zirconia Implants

Titanium implants, introduced by Branemark in the 1980s, have been very successful, with a high survival rate [52]; nevertheless, they are not without problems, particularly peri-implantitis and bacterial biofilm-mediated oxidation in an acidic environment [53]. As an alternative, Sadowsky [54] indicated that “zirconia implants offer a potential solution to the esthetic and biological limitations of titanium implants”. Osseointegration is defined as the structural and functional connection between bone tissue and the surface of a load-carrying implant [55]. It is essential for implant stability, implant loading and the long-term success of dental implants, and involves the interlocking between alveolar bone and the implant body and subsequent biological integration involving remodeling in the direction of the implant [55]. One of the important factors in the osseointegration capability of tetragonal zirconia polycrystal is its surface modification, including surface wettability, which may facilitate protein adsorption and interaction with cells [56]. The surface topography may be altered by alumina blasting and hydrofluoric acid etching, and the physicochemistry may be altered by exposure to oxygen plasma, ultraviolet light and hydrogen peroxide. Treatments to generate hydrophilic surfaces improved the attachment of osteoblast-like cells and changed the morphology of the cells [57]. These results indicate that Blast/Etch, O₂-Plasma, or UV treatments have potential for the creation and maintenance of superhydrophilic surfaces and enhancing the initial attachment of osteoblast-like cells. Sadowsky [54] emphasized the importance of developing procedures to eliminate the potential problem of zirconia’s low temperature degradation, including additive manufacturing and three-dimensional printing [58]. Using the latter technique, Zhang et al. [58] obtained a unique surface with a directional lamellar pore morphology, a strength comparable to conventionally manufactured zirconia implants, as well as a favorable osteoblast response. Nevertheless, design and material enhancements and long-term evaluations are still necessary.

11. Pulpotomy in Mature Posterior Teeth

Irreversible pulpitis is one of the most common causes of emergency visits to a dental care facility [59,60,61]. Minimally invasive procedures in dentistry are preferred, such as the preservation of the vitality of the pulp [62,63,64]. Partial or complete pulpotomy is a type of vital pulp therapy that involves the removal of the inflamed and infected pulp, while preserving the healthy pulp that can eventually heal [65]. However, diagnostic and prognostic predictors of the success of pulpotomies are not well established [66,67,68]. In this Special Issue, McHugh et al. [69] carried out a scoping review to analyze these factors. They concluded that further research is necessary to identify reliable predictors of outcome.

12. Oral Health Management of Pediatric Patients with Inherited Bleeding Disorders

Inherited bleeding disorders, including hemophilia A, hemophilia B, von Willebrand disease and other rare factor deficiencies, cause abnormalities in blood clotting, resulting in an increased risk of excessive bleeding [70,71]. To minimize the risk of oral bleeding from gingival inflammation and periodontal disease, and to prevent the necessity of tooth extraction, it is essential for individuals with inherited bleeding disorders to exercise good oral healthcare [72,73]. Raikuna and Prabhu [74] reviewed the protocols for oral health management of pediatric patients with inherited bleeding disorders. They emphasized the importance of communication between hospital dental clinics and primary oral healthcare clinics in order to establish an effective and financially viable pathway for these patients. They also outlined some of the measures taken to alleviate the sequalae of invasive dental procedures, including coagulation factor replacement therapy [75], and the use of desmopressin [76], antifibrinolytic agents [77] and preformed splints.

13. Corticotomy-Assisted Orthodontic Treatment

Corticotomy-assisted orthodontics is a therapeutic procedure that facilitates orthodontic tooth movement by accelerated bone metabolism resulting from controlled surgical damage [78]. The acceptance of corticotomy-assisted orthodontics as a treatment option is low [79]. Patatou et al. [80] describe corticotomy-assisted orthodontic treatment, its historical and biological background and its contraindications and periodontal side effects. The authors conclude that good candidates for this type of orthodontic treatment are those “presenting crowding in either the upper or lower dental arch, with normal skeletal relationships and healthy periodontal status who are not under medications that slow down bone metabolism”. The main reason for not selecting this treatment is the fear of surgery. Sulewska et al. [81] carried out long-term observations on corticotomy-assisted orthodontic expansion of the upper arch, and concluded that this procedure is not followed by negative changes in periodontal status. Augmented corticotomy-assisted orthodontics provided a more favorable improvement of periodontal status around the mandibular anterior teeth for maxillary protrusion patients compared to conventional orthodontics [82].

14. Oral Biosensors for Monitoring Systemic Health

Salivary biomolecules can be used in the diagnosis of systemic and oral diseases, including cardiovascular disease, renal disease, systemic malignancies, diabetes, autoimmune diseases, infectious diseases, oral diseases, oral squamous cell carcinoma, oral fungal, bacterial and viral diseases and psychological disorders [83,84,85,86]. Analytes detected in saliva include hormones, steroids, antibodies, growth factors, cytokines, nucleic acids, proteins, exosomes and drugs [84,86]. In their review, Archer et al. [87] focused on various devices that could be used for monitoring biomarkers in saliva. These biomarkers included glucose, which could be detected by the use of glucose oxidase. They concluded that refinement of biosensor design and data analysis is required to improve patient acceptability.

15. Complete Arch Fixed Implant Prosthesis

The introduction of osseointegration in dentistry has enabled treatment planning for patients with missing teeth. Urethane dimethacrylates can be loaded with surfactant-modified glass fillers to generate a 3D-printed, photopolymerized, high-strength polymer that can be employed as an interim prosthesis before the insertion of implants. Although the hardness and elastic modulus of the material improved, the flexural strength and diametral tensile strength were not satisfactory [88]. As an alternative, urethane dimethacrylate was modified with acidic and hydrophobic comonomers; this modification produced extended urethane–urethane hydrogen bonding, which in turn improved polymerization reactivity and mechanical properties [89]. Its advantageous flexural strength and elastic modulus were the result of the complex generated by noncovalent bonds between the carboxyl groups of the acidic monomers and the imino groups of urethane dimethacrylates [90]. Sadowsky and Stansbury [91] present a case report on the digital workflow and additive manufacturing of an interim complete arch fixed implant prosthesis, which is supported by four loaded implants on the maxillary arch, using stackable guides and a 3D-printed high-performance urethane dimethylacrylate to improve precision, efficiency and prosthetic stability.

16. Concluding Remarks

The contributions to this Special Issue on Current Issues in Oral Health are expected to help expand the vision of oral healthcare providers and oral health researchers with regard to the many developments and problems in these areas and their potential solutions.