Conservative vital pulp therapy in children calls for the use of specific procedures whose objectives differ from the issues encountered in adults:
It is important for the temporary tooth to remain in the dental arch to preserve the mesiodistal space, the vertical dimension guiding the physiological positionally normal eruption of succedaneous teeth and to prevent the appearance of parafunctions.
The preservation of pulp vitality in the deciduous dentition is important as a means of avoiding all risks of periapical diseases that could compromise the fate of the permanent tooth.
Preserving pulp vitality in an immature permanent tooth is important for the apexogenesis of the tooth. When the tooth is mature, the therapeutic aims will also be directed towards preserving pulp vitality, especially as the patient is young.
For decades calcium hydroxide has been the only material available in cases of carious, traumatic or therapeutic pulp exposure in order to obtain pulp healing and dentin repair.
Since the mid-1990s, Mineral Trioxide Aggregate (MTA) has been recognised as the reference material for the conservative pulp vitality treatments such as pulpotomy in temporary teeth and partial pulpotomy in permanent teeth .
Experiments have shown that MTA induces the formation of dentin 'bridges' protecting pulp lesions markedly more effectively than that observed with calcium hydroxide.
According to various hypotheses, MTA-induced dentinogenesis could be due to this material's capacity to ensure marginal integrity, to its biocompatibility, its temporarily increased pH, or a combination of these.
Biodentine is a cement of the same class as MTA: this new calcium silicate-based material exhibits physical and chemical properties similar to those described for certain Portland cement derivatives. On the biological level, it is perfectly biocompatible and capable of inducing the apposition of reactionary dentin by stimulating odontoblast activity and reparative dentin, by induction of cell differentiation. It is a dentin substitute that can be used as a restorative coronal material (for indirect pulp capping) but can also be placed in contact with the pulp.
Its fast setting time allows either immediate crown restoration, or to make it directly intraorally 'functional' without fear of the material deteriorating.
The purpose of this article is to illustrate the clinical procedure for using Biodentine in paediatric dentistry through two clinical cases of a kind frequently encountered in everyday practice and in both of which the issue at stake is to preserve pulp vitality.
Clinical case 1: Cervical pulpotomy on a temporary tooth (figs 1a-i)
The eight-year-old patient presented at the dental surgery with numerous carious lesions, including a severe caries in tooth # 55 (grade 5 according to the ICDAS classification). This temporary tooth was asymptomatic but the volume of the invasive caries made pulp exposure seem a likely prospect after caries excavation.
Curettage of the carious lesion under an operative field led to exposure of the mesial pulp horn: the endodontic access was made, the vital pulp was amputated from the chamber by clean section at the entrances to the root canals. The chamber was copiously irrigated with normal saline solution. After
obtaining haemostasis (signifying the absence of any root disorders) the pulp chamber was filled with Biodentine (see Procedure) until the access cavity was completely filled as far as the occlusal surface. A more durable restoration in the form of a preformed pedodontic cap was put in place one month later.
The therapeutic objective was to preserve pulp vitality at the level of the roots and to prevent the onset of infectious complications at periapical level, in the vicinity of the succedaneous tooth bud.
Clinical case 2: Partial pulpotomy following pulp exposure during caries curettage on a permanent tooth (figs 1a-m)
The 14-year-old patient was referred by her orthodontist for treatment of a carious lesion in tooth # 36, a mature permanent tooth. First an MRI scan was performed.
After administering nerve block anaesthesia and preparing the operative field, the former restoration was taken out and caries curettage exposed 4 mm of pulp in the distal horn. Two millimetres of the inflammatory pulp tissue was removed using a round diamond bur mounted on a high-speed handpiece with irrigation until healthy pulp was reached (haemostasis was obtained).
This dentin microcavity was carefully filled with Biodentine before proceeding to fill the whole of the coronal cavity. One and a half months later, the pulp vitality of the tooth and the absence of pulp symptoms were confirmed by testing pulp sensitivity to cold: it was decided to carry out the final crown reconstruction in the form of a ceramic onlay. A part of the filling cement was left in place as a cavity liner on account of the sizable loss of substance; in all cases it is recommended to keep a minimum cement thickness of 2mm as pulp protection.
The purpose of direct pulp capping (here in the form of a partial pulpotomy) is to encourage pulp healing and to protect the pulp by the formation of a dentin bridge.
Discussion
The pulp in a temporary tooth has a similar structure to that in a permanent tooth, but the time needed for it to reach full development is considerably longer for the permanent tooth than for the temporary tooth. The relationship with the periodontium was established, as in the case of the permanent tooth by the apical area, but also by the pulpal and periodontal accessory channels. The pulp in primary teeth does have similarities with that present in immature permanent teeth (capacity for recovery), but at the same time there are major differences (proportionally greater pulp volume with longer and more slender pulpal horns, closer to the enamel surface and therefore with much more frequent and rapid pulpal involvement than in the permanent dentition in cases of carious lesions).
Primary teeth at stage M (maturation) and immature permanent teeth have a similar physiology: incompletely formed roots, developed vascularisation, a cellular potential, an ever-present possibility of repair: treatment is therefore directed at preservation of pulp vitality.
At stage S (stability) the physiology of the temporary tooth is comparable to that of the permanent tooth, and our treatments are always directed at preserving the tooth.
Thus, as illustrated by the first clinical case, the aim is to keep the temporary tooth on the arch. Indeed, this tooth is necessary as a place-holder and guides the eruption of the adult tooth. To ensure that it stays for a long time and in order not to compromise the succedaneous tooth (absence of any root disease that could infect the pericoronal sac of the bud of the adult tooth) it is preferable that the pulp in the primary tooth should be healthy. Biodentine will help keep the stumps of pulp alive because the material is impervious. With physical and chemical properties similar to those of MTA – accepted as the material of choice for pulpotomies on temporary teeth –Biodentine presents the additional advantage of a shorter setting time.
Finally at stage R (rhizolysis/involution), the physiology is directed at replacement, pathologies are evolving rapidly and irreversibly – even with the use of conservative therapies – pulp involvement will direct treatment towards extraction (treatment indications are more limited). We shall not be seeking to keep the tooth and vitality.
Thus pulpotomy, which is the treatment most commonly used in temporary teeth, is indicated for asymptomatic primary teeth at stage M, stage S, or early stage R in the presence of pulpal inflammation confined to the cameral pulp, and < 2/3="" tooth="">
The partial pulpotomy described in the second clinical case is more frequently performed in immature permanent teeth (better recovery capacity of the dental pulp) whose vital pulp is asymptomatic, in order to be able to proceed with building and root maturation and the placement of the apical dentinocemental junction (apexogenesis).
A mature tooth with exposed pulp in a young subject with no symptoms, a measured approach (less aggressive) with the aim of preserving pulp vitality in order that the root walls can thicken (secondary apposition of dentin to achieve root build-up and maturation – a measure of the durability of the dental organ), to keep the tooth as intact as possible is performed as first intention.
According to Shayegan et al in 2010 and About et al in 2010, Biodentine induces dentin bridge formation, in the same manner as MTA so one may observe the apposition of tertiary dentin in direct contact with the capping material (protective role to prevent dentin reinfection and pulpal inflammation).
The action mechanism of calcium silicate cements such as Biodentine involves the release of calcium hydroxide with a basic pH like calcium hydroxide with, in addition, impervious dentin-material interfaces, as well as a dissolution resistance that does not involve any reintervention.
Despite the low clinical hindsight, on account of the recent availability of the material, the available studies in the animal model lead us to expect excellent results in terms of preserving pulpal vitality, dentin bridge formation and absence of complications (internal resorption, canal filling).
Conclusion
Within the framework of this case report we have dwelt on pulpal vitality-preserving therapies in paediatric dentistry in which the pulpal exposure was of carious origin and in two specific clinical situations; the material is proposed also for the restoration of deep carious lesions by indirect pulp capping in the context of filling using a sandwich technique and for partial pulpotomy following pulpal exposure in the context of trauma affecting a permanent tooth. In paediatric dentistry this material is going to offer the advantages of rapid application in an emergency consultation without need for any preparation of the dentin surface, with the guarantee of imperviousness to avoid bacterial contamination, and one that can be left in situ for up to six months.
The various studies available enable us right away to add this material to our everyday treatment armamentarium, with the results of long-term clinical studies due to be available in the coming months.
References available on request.