Latentne formy zmian próchniczych dolnych trzecich zębów trzonowych u ludzi

Yurii P. Kostilenko, Roman V. Talash, Alla P. Stepanchuk

UKRAINIAN MEDICAL STOMATOLOGICAL ACADEMY, Poltava, Ukraine

 

ABSTRACT

Introduction: The most pronounced thinning of the enamel is in the intercuspal fissures of the third molars, which are characterized by a wide variety of shapes and sizes up to the abnormal disruption of their development and teething, which often causes all kinds of clinical complications.

The aim: The purpose of the paper was to obtain the data on the structural state of the third molars and identify their most damaged areas in the latent form of dental caries.

Materials and Methods: 10 lower third molars with an intact crown without clear external signs of tooth decay have been examined. The teeth were embedded into epoxy resin, using the “Himkontakt-Epoxy” glue. Upon the completion of full polymerization, the resulting epoxy blocks were cut by the separation disk. Afterwards, the cross-cut ends with the naked tooth tissues were grinded and polished to obtain even unscratched slice, which was subsequently etched in Trilon-B (disodium salt EDTA) with the follow up staining in 1% borax methylene blue solution. Epoxy tooth slices were studied with the light optics in the reflected light using the MBS-9 binocular loupe, equipped with a digital camera adapter.

Results: The process of tooth decay is of endogenous origin. The specimen of the third lower molar shows all pathomorphological signs of the latent carious lesions. Impacted lower third molar with deep carious was detected. It is obvious that, being in the subcortical zone of the alveolar ridge of the lower jaw, this abnormally developed tooth could not be exposed to any external effects.

Conclusions: The microscopic study of the tooth, found in the ovarian dermoid cysts, showed that it was affected by caries that completely excludes the exogenous factors in its origination. We hypothesize that the mechanism of tooth decay directly involves the immune responses, antigens of which are (in certain circumstances) proteins of the dentin and enamel. This is the rationale for introduction into the current nosology the term “carious disease” instead of “dental caries”.

 

Wiad Lek 2018, 71, 7, -1234

 

INTRODUCTION

Currently, in practical dentistry, there is still a simplified opinion that dental caries originates from certain local exogenous factors (bacterial, physical, chemical), leading to the perforating damage of the hard tooth tissues.

However, there are also attempts to justify the countervailing opinion that the dental caries is considered as a local manifestation of certain adverse changes in the internal environment of the body, contributing to the onset of tooth dysfunctional states in the pulp that adversely affect the structure of its hard tissues [1]. This view justifies the theory of the endogenous origin of the dental caries and, thus, permits it to be classified as a carious disease [5]. Consequently, the morphological substrate of the disease is the hard tooth tissues, the damage of which is very diverse in terms of the degree of manifestation, localization and the number of teeth involved into the process.

We have been interested in the publications, reporting that rounded smooth crown surfaces, as well as thick enamel are the most resistant to caries, whereas all sorts of pits, fissures and folds are the most vulnerable zones for the carious process [1]. It is known that molar teeth possess such anatomical features of the crown. In the meanwhile, the most pronounced thinning of the enamel is in the intercuspal fissures of the third molars, which are characterized by a wide variety of shapes and sizes up to the abnormal disruption of their development and teething, which often causes all kinds of clinical complications. In this respect, the form and incidence of the carious lesion of these teeth is of particular interest, though it is not fully elucidated in the literature to date.

THE AIM

The purpose of the paper was to obtain the preliminary data on the structural state of the random sampling of the third molars.

MATERIALS AND METHODS

10 lower third molars with the intact crown without marked external signs of tooth decay, which were extracted on various clinical indications, have been studied. As they were selected, they were stored in the 10% neutral formalin solution.

After a detailed examination and imaging, the teeth specimens were washed off from formalin and desiccated in alcohol and plain acetone. Further on the teeth were sorted into separate plastic cells of the corresponding size and embedded into epoxy resin, using the “Himkontakt-Epoxy” glue [2].

Upon the completion of full polymerization, the resulting epoxy blocks were cut by the separation disk to obtain two cross-sectioned halves of the tooth. Subsequently, the cross-cut end with the naked tooth tissues was grinded and polished to obtain the even unscratched slices. Since the enamel on the slice is bounded by the dentine on the one side, and the layer of the epoxy resin on the other side, the outer one, it becomes available for the directed and controlled etching in the decalcification agent, namely, Trilon-B (disodium salt EDTA). As a result, a gradually growing lacuna, the bottom of which is the enamel layer that reflects its internal structure, is formed between the dentine and external layer of the epoxy resin [2].

A moderate etching of the enamel is needed not only to clearly identify the topography of the enamel, but also to disclose the organic structures of the dentin, which are thus easy to stain with appropriate dyes; among them, the most available and effective is 1% borax methylene blue solution. Once the epoxy tooth slices are washed off and desiccated they are ready to be studied using the light optics in the reflected light. We used the MBS-9 binocular loupe, equipped with a digital camera adapter.

RESULTS AND DISCUSSION

As it has been already mentioned, during the preliminary inspection (prior to the embedment into the epoxy resin) none of the 10 specimens of the lower third molars had clear external signs of carious lesion. On the side of the occlusal surface the crown was of predominantly rounded square shape with 4 blunt cusps, separated normally by cross-shaped fissures, which is generally typical for the lower molars. Notwithstanding the classical shape of the intercuspal fissures in the lower third molars, the impairments in the form of grooves, pits and imperfections, various in its expressions, have been noted. However, some of these teeth were slightly defective in the form of enamel wear, mainly on the bucco-mesial cusp.

The analysis of the epoxy slices of this sample of teeth has revealed the specific configuration of the enamel on the occlusal surface of their crowns. As it turned out in the pits-and fissures area of the half of the studied teeth the enamel wears to the extent that in some places there is a limited exposure of the superficial dentin in their depth. Obviously, in such places a direct contact of dentin, as a living tooth tissue, with food debris and microorganisms is inevitable.

It was unexpected that in two of the ten teeth, which, during the external inspection, appeared to be the intact ones, there were clear signs of carious alteration in the spots of enamel wear. The morphological signs were so specific that there was no doubt in their carious origin. This can be seen from the microimages of the cross-sectioned epoxy slice of one of these teeth (Figure 1 A and B). The first one presents the overview of the specimen that permits to assesses the general structural state of the hard tooth tissue (the dentin and enamel) and their topological relationship in the area of the occlusal surface of the crown. First of all, the change of tinctorial properties during methylene blue staining revealed the various local defects in the form of light amorphous spots on the enamel, where one, the most noticeable, was in the area of intercuspal fissures and the other, somewhat blurred, were visible from the external imperfection of the chewing cusp. In a more distinct form, they are visible on the second image obtained with a larger magnification of the light microscope. The enamel defect in the intercuspal fissure is of special attention. First of all, this refers to the fact that it is tapered on the slice, the widen part of which borders directly with the surface layer of the dentin, and a narrowed part is directed into the intercuspal fissure, covered with thin layer of the superficial enamel. As a matter of fact, this is the reason for these enamel defects were invisible during the external inspection.

A thorough study of such alternative formations gives the grounds to consider that they occur as a result of disintegration of the enamel prisms, leading to the partial or complete homogenization of the Hunter-Schreger bands, which are difficult to be recognized in blurred state. This is particularly noticeable in comparison with the surrounding intact enamel, where these structures are clearly identified (Figure 1B). We hypothesize that this will be enough for a preliminary conclusion that here we have the case of a latent form of the fissure caries.

However, such arguments are not enough for the final conclusion about the nature of this damage to the enamel. The study of the structural state of the dentin in the area adjacent to the enamel defect will clarify this issue. In this regard, the microimages presented in Figure 1 are clearly illustrative. They demonstrate the pattern of dentin alteration, well-known from the description in the literature [2], which is specific to the tooth decay. Primarily, the focus of alteration is well recognized by the overall darker stain against the background of the surrounding intact dentin, which has a moderate basophile density. At the same time, the closer to the focus of the alteration, the more enhanced density is, reaching the maximum at its borders, thus fringing it in the form of a ray cone, the base of which is directed to the enamel, and the vertex to the pulp cavity. In other words, the focus of dentin alteration is similar to a radial projection directed from the pulp to the basal layer of the enamel. Radial orientation of the light fissural retracing, alternating with dark stripes enhances the marked prominence of its radiating type. The publications report that this form of dentin alteration is called the “dead tracts” [2]. Their pathogenetic nature was first found in the work of A.I. Petrenko [6], in which the author, using the transmission electron microscopy techniques has found a complete destruction of the peritubular dentin in the area of dentin alteration in dental caries, as a result of which the dentine tubes are stripped off their walls, transforming into extended ductuli, which radially permeate into the loosen intertubular substance.

Additionally, the findings of the study show that these dystrophic processes in their development lead to a complete local destruction of the dentin, resulting in the complete homogenization. Generally, these detrital local aggregations occur in the most superficial layers of the dentin, on the border with the basal enamel, which can be viewed in the microimage (Figure 1 B) on the left from the place of enamel alteration in the area of intercuspal fissure. Noteworthy, the widest “dead tracts” stretch towards the pulp cavity on the side of completely destroyed section of the dentin, whereas on the opposite side the dendritic fibers come out, penetrating into a partially altered enamel in the area of the imperfection of the chewing cusp. Currently, the nature of the latter formations is not known to date. However, the evaluation of this straight orientation of the formations shows a direct pathogenetic correlation between the dental pulp and decayed enamel, caused by the “dead tracts” of the dentin.

CONCLUSIONS

The above facts confirm the presence of all pathomorphological signs, indicating about the latent form of the carious lesions of the specimen of the third lower molar. Its origination (etiopathogenesis) can be interpreted in a twofold way, i.e., either as a result of exogenous damaging factors or as a consequence of functional impairments in tooth pulp. Currently, it is difficult to solve this dilemma clearly, since it is almost impossible to trace the dynamics of the development of tooth decay, starting from its onset.

However, we possess some persuasive, albeit indirect, facts that confirm the endogenous origin of the carious process. First, we had previously reported that the X-ray of the 72-year-old woman, made at the Department of Oral Surgery of the Ukrainian Medical Stomatological Academy (Poltava), revealed the impacted lower third molar with deep caries [3]. It is obvious that, being in the subcortical zone of the alveolar ridge of the lower jaw, this abnormally developed tooth could not be exposed to any external effects.

The second case, even more unique, refers to the teeth found in the ovarian dermoid cysts. The microscopic study has found that some of them were affected by caries [4], which completely excludes the exogenous factors in its origin.

We hypothesize that the mechanism of tooth decay directly involves the immune responses, antigens of which are (in certain circumstances) proteins of the dentin and enamel. This is the rationale for introduction into the current nosology the term “carious disease” instead of “dental caries” [5].

Perspectives of the further research will encompass the study of the tissues of the molar teeth found in the ovarian dermoid cysts.

REFERENCES

1. Borovskiy E.V., Ivanov V.S., Banchenko G.V. Terapevtichekaya stomatologiya, Moskva: “Meditsinskoe informatsionnoe agentstvo”, 2003:340 s.

2. Kostilenko Yu.P., Boyko I. V. Struktura emali i problema kariesa, Poltava: OOO NPP „Ukrpromtorgservis”, 2007:55 s.

3. Kostilenko Yu.P., Boyko I. V., VoloshinaL. I. Glubokiy karies retenirovannogo anomalno razvivshegosya zuba, DentArt. 2012;4:14-16.

4. Kostilenko Yu.P., Starchenko I. I., Prilutskiy A. K. Stroenie zubov v zreloy teratome yaichnika, Arhiv patologii, 2015;22(77):28-31.

5. Okushko V.R. Fundamentalnaya odontologiya i karioznaya bolezn, DentArt, 2010;3:71-74.

6. Petrenko A.I. Ultrastrukturnaya harakteristika alteratsii dentina zubov cheloveka pri fiziologicheskom istiranii emali i kariese, Visnik problem biologiyi I meditsini, 2010,Vyip. II:217-220.

 

The research has been carried out within the research scientific work, entitled “Age-related aspects of the structural organization of the organs of the human immune system, glands of gastrointestinal and urogenital system in normal condition and pathology”; State registration number State registration number: 0106U004192, 2016-2020, Oleg O. Sherstyuk.

Authors’ contributions:

According to the order of the Authorship

Conflict of interest:

The Authors declare no conflict of interest

CORRESPONDING AUTHOR

Roman V. Talash

Ukrainian Medical Stomatological Academy

Departament of Human Anatomy

23 Shevchenka Str, 36011, Poltava , Ukraine

tel: +380668903438

e-mail: roman_talash@ukr.net

Received: 16.07.2018

Accepted: 25.09.2018

Superficial etching in the Trilone-B; methylene blue stain. А – lens 2, B – lens 7:

1 – pulp cavity, 2 – dentin, 3 – enamel, 4 – enamel alteration in the area of chewing cusp imperfection; 5 – enamel alteration in the area of intercuspal fissure; 6 – area of dentin alteration (“dead tracts”), 7 – detritus of the altered dentin.

Fig. 1. Longitudinal epoxy slice of the lower third molar.