Root Caries: From Prevalence to Therapy

M. Rocha de Olivera Carrilho

• Éditeur: S. Karger
• Année: 2017
• ISBN:
  9783318061130
• Sujet: Medicina
• Sous-sujet: Odontotecnica

Case reports and clinical trials conducted in various countries show, more and more frequently, a positive correlation between the presence of original teeth and prevalence of root caries in older age. Because this is a global trend, it is likely that the predicted increase in the worldwide elderly population may soon cause a significant increase in the number of people requiring effective means of preventing and treating root surface caries. In response to this development, a team of outstanding contributors has reviewed the most important aspects of root caries. This new volume presents their findings along with discussions of how to deal with this health issue that progressively affects the oral health balance. The chapters in this book are divided in four core parts: Epidemiology, Biological Determinants, Lesion Assessment and Features and Preventive and Operative Therapies. The collection of state-of-the-art articles provides a broad overview and will serve as a reference for clinicians as well as scientists and, hopefully, will encourage new research.

Preventive and Operative Therapies

Carrilho MRO (ed): Root Caries: From Prevalence to Therapy.
Monogr Oral Sci. Basel, Karger, 2017, vol 26, pp 76–82 (DOI: 10.1159/000479348)

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Biofilm Control and Oral Hygiene Practices

Marisa Maltz^a · Luana Severo Alves^b Julio Eduardo do Amaral Zenkner^b

^aFederal University of Rio Grande do Sul, Porto Alegre, and ^bFederal University of Santa Maria, Santa Maria, Brazil

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Abstract

As the thick biofilm in the presence of fermentable carbohydrates is the main etiological factor of dental caries, the frequent and systematic removal of this colony by means of an effective biofilm control should result in the prevention of caries lesions or in the arrest of the local carious process. However, the role of biofilm control in the management of dental caries has been questioned. This chapter will discuss the biofilm control and oral hygiene practices on root surfaces. Laboratory and clinical studies describing the effect of biofilm control and oral hygiene practices on the arrestment of root carious lesions are described. Epidemiological surveys evaluating the association between oral hygiene and root caries are discussed. Finally, some aspects on chemical biofilm control are also presented.

© 2017 S. Karger AG, Basel

Introduction

Dental caries is a multifactorial disease whose main biologic determinant is the dental biofilm. It causes a chemical dissolution of dental tissues due to the presence of acids that are derived from the fermentation of sugar by microorganism of the dental biofilm. On the contrary, while dental biofilm is essential for the development and progression of dental caries, it is not sufficient for the disease to occur. As the thick biofilm in the presence of fermentable carbohydrates is a key etiological factor for dental caries, the frequent and systematic removal of this colony of microorganisms by means of an effective biofilm control should result in the prevention or in the arrestment of caries lesions. However, the role of biofilm control (mechanical and chemical) in the management of dental caries has been questioned since conflicting results have been reported.

This chapter will discuss the biofilm control and oral hygiene practices on root surfaces. It is important to recognize that the formation of a root carious lesion differs, in some important aspects, from the development of coronal caries, as described in the chapter by Damé-Teixeira et al., this volume, pp. 15–25. Enamel carious lesions progress reflecting the direction of enamel prisms, and due to its high mineral content, usually present sharp limits at the surface angle. In general, the depth of coronal lesions tends to exceed its width, thus resulting in a retentive cavity commonly inaccessible for cleaning by the patient. Conversely, root lesions, mainly located in dentin, progress shallowly, usually resulting in saucer-shaped cavities. The expulsive configuration of root lesions simplifies the mechanical removal and control of dental biofilm. Usually, such lesions are easily accessible to the patient.

Laboratory and clinical studies describing the effect of biofilm control and oral hygiene practices on the arrestment of root carious lesions are described in this chapter. Epidemiological surveys evaluating the association between oral hygiene and root caries are discussed. Finally, some aspects of chemical biofilm control are also presented.

It is important to point out that the introduction of fluoridated dentifrices in the second half of 20th century has somehow disturbed the possibility of getting a reasonable understanding about the role of biofilm control alone in the prevention/control of dental caries. In most cases, toothbrushing is performed using fluoridated dentifrices and a great variety of fluoridated products are available for domiciliary use. These facts make it difficult to isolate the role of self-performed biofilm control in the conservative treatment of carious lesions, including those at root surfaces.

Mechanical Biofilm Control

Laboratory Studies

There are a few laboratory studies assessing the effect of biofilm control on the treatment of root carious lesions. Nyvad et al. [1] published the results of an in situ study testing the hypothesis that oral hygiene measures associated with topical fluoride was able to arrest the carious process and to reduce the ongoing mineral loss in active root lesions. Sound root surface specimens were inserted into the lower partial dentures of 18 healthy subjects, and the biofilm removal in these specimens was suppressed during 3 months, aiming at the development of carious lesions. Over the following 3 months, individuals allocated in the test group were instructed to brush the root specimens meticulously once a day with 1,100 ppm fluoride toothpaste, which was supplemented with two intra-oral topical application of 2% solution of sodium fluoride (NaF) for 2 min. Participants allocated in the control group performed no brushing and received no topical fluoride. This in situ study showed that the total mineral content of root lesions submitted to daily biofilm control and topical fluoride for 3 months remained unaltered, with no further detectable mineral loss. Additionally, an increase in the mineral content at the surface layer of the treated root lesions was observed. The authors concluded that the oral hygiene regime, composed of daily biofilm removal and topical fluoride, may arrest the lesion progression in carious root surfaces.

To the best of our knowledge, this is the unique in situ study available in the literature addressing this issue. On the contrary, there are some experimental in situ and in vivo studies that provide evidences supporting the effect of oral hygiene on enamel caries [2–4]. These studies show that the elimination of oral hygiene procedures lead to the development of non-cavitated enamel lesions [2] and that regular mechanical biofilm control resulted in no further mineral loss [3] and in clinical arrestment of the lesion [4].

Clinical Studies

Oral hygiene is critical in the caries control process; nevertheless, there are also clinical evidences showing the benefit of supplementing oral hygiene procedures with chemical agents to achieve root caries control [5]. A recent systematic review, which collected and analyzed the clinical evidence concerning the efficiency of noninvasive treatments for root caries, concluded that “root caries could be controlled at the population level by daily brushing with fluoride-containing toothpastes, whilst active decay may be inactivated using professional application of fluoride varnishes/solutions or self-applied high-fluoride toothpaste [5].” Studies on coronal caries also showed that for most subjects, tooth-brushing performance may be insufficient to control caries when using a fluoride-free toothpaste [6–8].

Studies on root caries control often motivate patients to perform oral hygiene [5]. This emphasizes the importance of biofilm control in the management of root caries. In a series of 24 cases of root cavities, Nyvad and Fejerskov [9] demonstrated the possibility of arresting root cavities by means of oral hygiene and topical fluoride. Initially, the carious lesions were greasy, yellowish, or light brownish, with a soft aspect under light probing (active lesions). The ten adult patients included in the study received instruction on oral hygiene mainly focused on their root cavities. During the same appointment, patients performed supervised biofilm removal, and the lesion received an application of 2% NaF solution for 2 min which was repeated after 8 weeks. The domiciliary hygiene procedures consisted of two daily toothbrushing period with a 1,000 ppm F dentifrice. No other source of fluoride was applied during the experimental period and the aspect of lesions concerning texture, color, and surface structure were registered for 18 months. Biofilm and/or gingival trauma were detected rarely and, in these cases, adjustments on the domiciliary toothbrushing technique were performed. Gradual changes in the color and surface texture were observed over the inactivation process, with lesions becoming harder and darker, with smoother margins and contours.

In another study, the possibility of converting active root carious lesions into inactive lesions by a 12-month prophylactic program with emphasis on oral hygiene procedures was evaluated [10]. In this program, 15 caries-active individuals received intensive oral hygiene training on an individual basis in the first 3 months (3–7 visits). Professional cleaning and application of fluoride varnish were performed at 3-, 6-, and 9-month visits. After 12 months of intervention, the number of active lesions decreased from 99 to 46, which represents an inactivation rate of around 50%. The authors also found that the proportion of lesions becoming inactive was not similar among the different root surfaces. Root caries lesions located at buccal and lingual surfaces were more likely to arrest over the study period than those located at approximal surfaces. This finding emphasizes the importance of accessibility to biofilm control of every dental site on a regular basis aiming at lesion arrestment.

In addition to these studies that assessed specifically the effect of oral hygiene and fluoride on the arrestment of active root cavities, there is some evidence derived from the control groups of clinical trials comparing products. Recently, a controlled clinical trial by Zhang et al. [11] compared 3 strategies to prevent and arrest root caries among community-dwelling elders from Hong Kong: group 1 (the control group) received oral hygiene instr...