*Anna Szufnara1, Sylwia Majewska-Beśka2, Joanna Szczepańska2
Treatment methods of deep caries in immature permanent teeth
Metody leczenia próchnicy głębokiej w zębach stałych niedojrzałych
1Doctoral Studies, Department of Paediatric Dentistry, Medical University of Łódź, Poland
Head of Department: Professor Joanna Szczepańska, MD, PhD
2Department of Paediatric Dentistry, Medical University of Łódź, Poland
Head of Department: Professor Joanna Szczepańska, MD, PhD
Próchnica została zakwalifikowana przez ONZ do grupy chorób przewlekłych nieinfekcyjnych (NCD). Można jej uniknąć poprzez działania profilaktyczne. Szczególnie głębokie zmiany próchnicowe w zębach stałych z niedokończonym rozwojem korzenia stanowią poważny problem leczniczy dla współczesnej stomatologii. Spowodowane jest to odmienną budową anatomiczno-histologiczną w porównaniu z zębami dojrzałymi. Uzasadnieniem dla wyboru tematyki było przedstawienie na podstawie przeglądu piśmiennictwa współczesnych metod leczenia próchnicy głębokiej w zębach stałych z niezakończonym rozwojem morfologicznym i histologicznym z uwzględnieniem stosowanych obecnie materiałów biokompatybilnych.
Dokonano przeglądu piśmiennictwa na podstawie baz Pubmed i Elsevier w przedziale lat 2005-2018 oraz dwóch artykułów spoza zakresu. Kryterium wyszukiwania były następujące hasła: „próchnica”, „remineralizacja”, „pokrycie pośrednie”, „zęby niedojrzałe”.
Rozwój medycyny i nauk biologicznych stwarza szansę na powstawanie nowych protokołów postępowania i leczenia próchnicy głębokiej. Większość z nich opiera się na filozofii stomatologii minimalnie inwazyjnej. Rozwój bioinżynierii pozwala na wytworzenie coraz bardziej biozgodnych materiałów, które nie wywierają drażniącego wpływu na miazgę zęba, natomiast umożliwiają głęboką remineralizację tkanek, co jest szczególnie istotne w przypadku zębów niedojrzałych.
W leczeniu próchnicy głębokiej nadal wykorzystywane są preparaty z wodorotlenkiem wapnia czy tlenkiem cynku z eugenolem lub szkło-jonomery. Na powodzenie podjętego leczenia duży wpływ mają: współpraca z pacjentem, możliwość wczesnej diagnozy oraz kontrola już leczonych zębów. Niezbędne są dalsze badania nad metodami diagnostyki i leczenia, pozwalające we wczesnym etapie na regenerację zmian jakościowych, zapobiegając powstawaniu ilościowych uszkodzeń struktury twardych tkanek zęba.
Caries was qualified by UN as non-communicable disease – NCD. It can be avoided by preventive measures. Especially, deep caries lesions in immature permanent teeth constitute a serious clinical problem for contemporary pediatric dentistry.
It is caused by a different anatomical and histological structure compared to mature permanent teeth. The aim of the study was to present contemporary methods of deep caries treatment in histologically and morphologically immature teeth with currently used materials.
The literature review was based on Pubmed and Elsevier databases (2005-2018) and two articles out-of-range. The search criteria were: “caries”, “remineralization”, “indirect capping” and “immature teeth”.
Development in medicine and biomedical science leads to creating more modern procedural records when it comes to deep caries treatment. They are based on minimally invasive dentistry. Development of bioengineering enables creation of more biocompatible materials which do not have irritating influence on dental pulp. These materials allow deeper remineralization of dental tissues.
Deep caries treatment still involves usage of restorations with calcium hydroxide, zinc oxide with eugenol and glass ionomers. Good cooperation with patient, prospects of early diagnosis, and regular examinations of treated teeth have great impact on success of treatment. Further research on methods of diagnosis and treatment needs to be carried out. They should allow regeneration of early qualitative changes to avoid quantitative damages in a tooth’s hard tissue.
Deep caries and its complications in immature permanent teeth still constitute a serious treatment problem for modern dentistry. According to research conducted under the supervision of the Ministry of Health in Poland in 2013-2015, 4% of 12-year-old children had at least one extracted permanent tooth due to caries. Among 18-year--olds, this percentage is as high as 15% (1). According to World Health Organization’s (WHO) definition, caries is a local pathological process of extracorporeal origin leading to enamel decalcification, decay of tooth’s hard tissues and consequently to formation of cavity (2). In 2011, under the influence of FDI (World Dental Federation) dental caries was qualified by UN Council to the group of chronic non-infectious non-communicable diseases (NCD) which can be avoided through preventive measures. It is a multifactorial process as its etiology was described many years ago. Its etiopathogenesis does not depend on one pathogen causing the disease. Development of caries involves acid-forming bacteria in the biofilm which reside in the oral cavity, however without proper conditions for their growth and thus without significant increase in their number, they will not cause decay. Simultaneously, it is not possible eradicate all oral bacteria that contribute to development of caries (3, 4).
Immature teeth are more susceptible to caries and its complications than teeth with fully developed apices, also due to their lower mineralization, higher amount of interprismatic substance, a thin layer of dentin with wide dentinal tubules, as well as large chambers and prominent pulp horns (5). Fast progress of carious lesions in permanent teeth in children is often an indication for phased treatment including indirect pulp capping with the use of preparations for remineralizing tooth tissues. They are to prevent pulp exposure and limit penetration of microorganisms and products of their metabolism deep into the tissue and, consequently, stop pulp necrosis.
Regenerative abilities of dentin left on the pulpal wall of cavities are used in treatment deep caries. Demineralized layer of dentin, free of bacteria, has remineralizing properties. In response to applied treatment, tertiary dentine is formed on the border with the pulp, which constitutes the body’s defense response to irritating external factors.
The aim of the study was to present – on the basis of literature review – methods of treating deep tooth decay in permanent teeth with incomplete morphological and histological development, taking into account currently used biocompatible materials.
Review of the current state of knowledge
Material and methods
The literature review was based on Pubmed and Elsevier databases covering the period 2005-2018 and two papers out-of-range. They were analyzed in terms of therapeutic methods and materials applied in treatment of deep caries in permanent teeth with incomplete development. The search criteria were the following key words in Polish and their equivalents in English: “caries”, “remineralization”, “indirect capping”, “immature teeth”. The literature available in text databases of the Medical University of Łódź was used. 44 items were selected. The paper presents methods of indirect pulp capping and materials such as: zinc oxide with eugenol, calcium hydroxide, Biodentin, light-curing liners, biomaterials, glass ionomer materials.
Minimally invasive dentistry
Minimally invasive dentistry is a concept of early detection of carious lesions, bacteria reduction, use of dental materials requiring the least possible tooth preparation, repairing fillings instead of their complete replacement, preparation of the cavity with the least possible loss of tooth’s hard tissues in a way that is as little irritating to the pulp as possible (6, 7). In the case of treating deep caries, it consists in removal of the soft infected layer of irreversibly infected dentin. On the pulpal wall remains affected dentin, undergoing demineralization process to the extent that allows remineralization, because apatite crystals are bonded with collagen fibers by means of cross-links similar to those in healthy dentin, thanks to which the collagen structure is preserved and at the same time devoid of bacteria (8). Research shows that tight closure of a cavity causes inactivation of any bacteria left inside due to lack of carbohydrates needed for their nutrition (7). Further preparation of a deep cavity and removal of demineralized tissue carry a risk of pulp exposure (9). Overpreparation of dental tissues also makes them more susceptible to damage by mechanical and chemical factors.
Methods of deep caries treatment
In clinical practice, the most common method of treating deep caries is the indirect capping method. As defined by the American Association of Endodontists, it consists in placing dental material on a small left layer of demineralized dentin, whose removal would result in pulp exposure (10). There are two types of indirect capping:
1. single-stage method (the “one-visit IPT” [indirect pulp treatment]) – requiring one patient visit, during which the dentist places the final filling,
2. two-stage method (the “two-visit IPT”) – during the second visit the previously placed temporary filling is removed and the chamber bottom is thoroughly prepared.
The differences in these methods relate to dental materials used and protocols of tooth surface preparation for treatment procedures.
Indications for indirect pulp capping
Before deciding on treatment with the indirect coating method, the dentist should obtain full history from the patient, which would exclude irreversible pulpitis, and perform a physical examination (8, 11). Teeth qualified for indirect capping cannot demonstrate spontaneous pain ailments, the patient should not feel pain when consuming warm food. However, an increased reaction to cold is allowed. The tooth should not demonstrate sensitivity to vertical and horizontal percussion. The patient can react with pain to drilling during cavity preparation. A radiological examination should show no pathological lesions in the apices of the tooth, periodontium and surrounding bone. Additional examination that can be helpful in diagnosis is the Doppler flowmeter viability test, the result of which should be within the reference ranges. Another useful procedure for determining the degree of cavity preparation is staining of demineralized dentin with preparations based on glycol propylene, which only stains denatured collagen (12). In in vitro studies, Krause et al. (13) showed that when determining the thickness of left dentin that separates the cavity bottom from the pulp chamber, optical coherence tomography can be used. It is a non-invasive examination method, using infrared light for evaluation of surfaces of partially transparent objects. It is safe due to the lack of x-ray emission.
The impact of the carious process on adhesion of dental materials to tooth tissues
The carious process causes local increase in the amount of organic substances and water in tooth’s hard tissues, which adversely affects adhesion of dental materials, especially light-cured ones, requiring the base to be dry during application. In deep carious cavities, a negative impact on adhesion of fillings is made by large dentinal tubules, especially those present in the vicinity of the pulp of immature teeth, and by smaller surface and lower mineralization of intertubular dentin. After cavity preparation, a layer of impurities is formed called a smear layer, the removal of which is difficult even in the etching process (14).
In response to chronic pathological stimuli, what follows is obliteration of dentinal tubules in the formation process of reparative or sclerotic dentin. Mineral deposits are not susceptible to 15-second etching recommended by producers, they prevent formation of microvilli layer and adhesion of light-curing materials. Extension of curing time to over 15 seconds recommended in adhesive protocols causes excessive demineralization of dentin, degradation of collagen fibers and deterioration of light-curing materials’ adhesion. Application of etchant and bonding systems in deep cavities can negatively affect the pulp, especially of immature teeth, because free monomers can pass through a thin, demineralized layer of dentin and its large dentinal tubules (15-17).
Materials used in treatment of deep caries – dentin remineralization
Zinc oxide with eugenol
In fact, for many years the only treatment of deep caries was partial preparation of the cavity leaving slightly demineralized dentin on the pulpal wall, and then filling the tooth for three months with zinc oxide with eugenol. Currently, improved versions of this material are emerging, reinforced with polymethyl methacrylate, e.g. IRM (18). It has antimicrobial properties against bacteria from the Streptococcus mutans and Enterococcus faecalis groups (19). However, studies show its large marginal leakage and high cytotoxicity to pulp (20, 21). The producer recommends replacement of IRM temporary filling in less than 12 months. The material should not be used as a liner for permanent filling containing resin due to eugenol content and its negative impact on the polymerization process.
The most common method of deep caries one-visit IPT is placing calcium hydroxide liner on highly demineralized pulpal wall and filling it tightly with light-cured material (8, 22). The two-visit IPT protocol assumes partial preparation of carious cavity, application of calcium hydroxide liner and closing the tooth with resin-reinforced zinc oxide with eugenol, e.g. IRM. After three months, the filling is carefully removed and the bottom of the chamber is thoroughly prepared (22). The therapeutic aim of using calcium hydroxide liner is stimulation of reactive dentin formation, and isolation of pulp from thermal and chemical stimuli (23). Calcium hydroxide, so frequently used as a liner in indirect capping, has bactericidal properties resulting from its high pH (24). However, a meta-analysis conducted by Brazilian scientists showed that use of calcium hydroxide liner under clinical conditions does not significantly affect positive treatment outcome in the staged method of caries removal (23).
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