Dental sealants (also termed pit and fissure sealants, [1] or simply fissure sealants) [2] are a dental treatment intended to prevent tooth decay. Teeth have recesses on their biting surfaces; the back teeth have fissures (grooves) and some front teeth have cingulum pits. It is these pits and fissures that are most vulnerable to tooth decay because food and bacteria stick in them and because they are hard-to-clean areas. Dental sealants are materials placed in these pits and fissures to fill them in, creating a smooth surface which is easy to clean. Dental sealants are mainly used in children who are at higher risk of tooth decay, and are usually placed as soon as the adult molar teeth come through.
Dental caries is an upset of the balance between loss and gain of minerals from a tooth surface. [3] The loss of minerals from the teeth occurs from the bacteria within the mouth, fermenting foods and producing acids, whereas the tooth gains minerals from our saliva and fluoride that is present within the mouth. [3] When this balance is skewed due to frequent intake of fermentable carbohydrates, poor oral hygiene, and lack of fluoride consumption, there is a continuous loss and little gain of minerals over a long period of time, which can ultimately cause what is known as tooth decay. [3]
Dental sealants are a preventive treatment that is part of the minimal intervention dentistry approach to dental care. [4] These sealants are a plastic material placed in the pits and fissures (the recesses on the chewing surfaces) of primary (baby) or permanent (adult) molar and premolar teeth at the back of the mouth. These molar teeth are considered the most susceptible teeth to dental caries due to the anatomy of the chewing surfaces of these teeth, which inhibits protection from saliva and fluoride and instead favours plaque accumulation. [5] This approach facilitates prevention and early intervention, in order to prevent or stop the dental caries process before it reaches the ends stage of the disease, which is also known as the "hole" or cavitation of a tooth. [4] Once the tooth is cavitated, it requires a dental restoration in order to repair the damage, which emphasizes the importance of prevention in preserving teeth for a lifetime of chewing.
Preventing tooth decay from the pits and fissures of the teeth is achieved by dental sealants providing a physical barricade to protect natural tooth surfaces and grooves, inhibiting build-up of bacteria and food trapped within such fissures and grooves. Dental sealants also provide a smooth surface that is easily accessible for both the natural protective factor, saliva and the toothbrush bristles when cleaning the teeth. [6] As dental sealants are clear or white, they are only visible upon close inspection.
Multiple oral health care professionals including dentists, dental therapists, dental hygienists, oral health therapists and dental assistants (in some states in the US) are able to apply dental sealants to teeth. [6]
There have been many attempts made within past decades to prevent the development of caries, in particular occlusal caries as it was once generally accepted that pits and fissures of teeth would become infected with bacteria within 10 years of erupting into the mouth. [7] G.V. Black, the creator of modern dentistry, informed that more than 40% of caries incidences in permanent teeth occurred in pits and fissures due to being able to retain food and plaque. [8]
One of the first attempts to prevent occlusal caries occurred as early as 1905 by Willoughby D. Miller.[ citation needed ] Miller, a pioneer of dentistry, was applying silver nitrate to surfaces of teeth, chemically treating the biofilm with its antibacterial functions against both Streptococcus mutans and Actinomyces naeslundii, which are both carious pathogens. [7] [8] [9] Silver nitrate, which was also being practiced by H. Klein and J.W. Knutson in the 1940s, was being used in attempt to prevent and arrest occlusal caries. [8] [10]
In 1921, T.P. Hyatt, a pioneer researcher, was the first person to recommend prophylactic odontotomy (preventive operation). [8] [11] This procedure involved creating Class 1 cavity preps of teeth that were considered at risk of developing occlusal caries, which included all pits and fissures. [8] [11] The widening of the pits and fissures were then filled with amalgam. [8] [11]
C.F Bödecker, a dentist and researcher, also made attempts to prevent occlusal caries. Initially, in 1926 Bödecker would use a large round bur to smooth out the fissures. 1929, Bödecker attempted to prevent occlusal caries by cleaning the pit and fissures with an explorer and then sealing the pits and fissures with dental cement, such as oxyphosphate cement.[ citation needed ] Bödecker then later became an advocator for prophylactic odontotomy procedures (preventive operations). [11]
It was in 1955, that M.G. Buonocore gave insight to the benefits of etching enamel with phosphoric acid. [7] [8] His studies demonstrated that resin could be bonded to enamel through acid etching, increasing adhesion whilst also creating an improved marginal integrity of resin restorative material. [8] It was this bonding system that led to the future successful creation of fissure sealants. [7] [11]
In 1966, E.I. Cueto created the first sealant material, which was methyl cyanoacrylate. [1] However, this material was susceptible to bacterial breakdown over time, therefore was not an acceptable sealing material.[ citation needed ] Bunonocore made further advances in 1970 by developing bisphenol-a glycidyl dimethacrylate, which is a viscous resin commonly known as BIS-GMA. [1] This material was used as the basis for many resin-based sealant/composite material developments in dentistry, as it is resistant to bacterial breakdown and forms a steady bond with etched enamel. [1]
In 1974, glass ionomer cement fissure seals (GIC) were introduced by J.W. McLean and A.D. Wilson. [1]
Modern dental sealants generally are either resin based or glass ionomer based. [1]
It is customary to refer to the development of resin based sealants in generations: [1] [12]
As part of the wider debate over the safety of bisphenol A (BPA), concerns have been raised over the use of resin based sealants. [1] BPA is a xenoestrogen, i.e. it mimics the relative bioactivity of estrogen, a female sex hormone. Pure BPA is rarely present in dental sealants, however they may contain BPA derivatives. [1] There is very little research about the potential estrogen-like effects of BPA derivatives. [1] A transient presence of BPA in saliva has been reported immediately following placement of some resin based sealants. [1] The longest duration of salivary BPA was 3 hours after placement, so there is little risk of chronic low-dose BPA exposure. The currently available evidence suggests that there is no risk of estrogen-like side effects with resin based sealants. [1] Several national dental organizations have published position statements regarding the safety of resin based dental materials, e.g. the American Dental Association, [nb 1] the Australian Dental Association, [nb 2] the British Dental Association, [nb 3] and the Canadian Dental Association. [nb 4]
GIC materials bond both to enamel and dentine after being cleaned with polyacrylic acid conditioner.[ citation needed ] Some other advantages GICs have is that they contain fluoride and are less moisture sensitive, with suggestions being made that despite having poor retention, they may prevent occlusal caries even after the sealant has fallen out due to their ability to release fluoride. [1] [13]
There is evidence that GIC sealant that were exposed to thermo-light curing [14] with a LED polymerization unit (60 s) had comparable sealing ability and superior sealing characteristics compared to the conventional resin-based sealant. [15]
It was shown that GIC materials were more effective in prevention of development of caries despite the higher non-successful rate compared to resin based sealants. [16] This may be accounted for due to the fluoride-releasing property of GIC which increases salivary fluoride level that may aid in preventing dental caries.
Resin-based sealants are normally the preferred choice of material for denture sealants. GIC material may be used as a provisional protective material when there are concerns regarding adequate moisture control. [17]
Dental sealants are accepted as an effective preventive method for cavities and as long as the sealant remains adhered to the tooth, cavities can be prevented. It is for this reason that sealant success is now measured by the length of time a sealant remains on the tooth, rather than the decay experienced in sealed and unsealed teeth. The ability of a pit and fissure sealant to prevent dental caries is highly dependent on its ability to retain on the tooth surface.
It has been demonstrated that the use of adhesive systems before applying dental sealants improves retention.[ citation needed ] Traditional retention of a sealant on tooth surface is through acid etching.
The most common reason for sealant failure is salivary contamination during sealing placement. Other factors include clinician inexperience, lack of client co-operation, and less effective sealant material used. [18]
Sealants may be applied in conjunction with fluoride varnish as a preventive method which is shown to be more successful (low certainty evidence) than fluoride varnish alone. [19]
Various factors can help contribute to the retention of fissure sealants. These include:
Although dental sealants do wear naturally and may become damaged over time, they usually last for around five to ten years, despite the heavy pressures endured by teeth during chewing each day. Longevity of dental sealants is also dependent on the type of material used. [21] It is not uncommon for dental sealants to be retained well into adulthood.[ citation needed ] It is believed that bacteria and food particles may eventually become entrapped under dental sealants, and can thus cause decay in the very teeth intended to be protected.[ medical citation needed ] Dental sealants are inspected during routine dental visits to ensure that they are retained in the fissures of the teeth. Damaged sealants can simply be repaired by adding new sealant material. One of the major causes of the loss of sealants in the first year is salivary contamination. [20]
On the basis of limited evidence both GIC and resin materials are equally acceptable in caries prevention, however retention rates between GIC and Resin have been shown to differ. [13] Resin has been shown to be the superior product for retention. A 2-year clinical trial comparing GIC and Resin for dental sealants demonstrated that the GIC had a total loss rate of 31.78%, in contrast to the resin which had a total loss rate of 5.96% The study did acknowledge that GIC had its therapeutic advantages other than retention, this included the benefit of fluoride release and its use on partially erupted teeth. [22] Though GIC has poorer retention rates, the fact that they release active fluoride in the surrounding enamel is very important. They can exert a cariostatic effect and increased release of fluoride, and for these reasons GIC is more of a fluoride vehicle rather than a traditional fissure sealant. [23] All three materials are as effective as each other if the correct techniques are used to complete the procedure. [13]
Although dental sealants are recommended to be placed in all children as soon as possible following eruption of permanent molars there are specific indications for when they are required to be placed. These indications mainly stem from issues that would cause a patient to be considered high caries risk, in order to prevent dental caries.
These indications are:
There are no specific contraindications to placing dental sealants. For resin fissure sealants to be successful excellent moisture control is needed during placement of the fissure sealant. In cases where moisture control cannot be achieved then Glass Ionomer fissure sealants should be placed until a time where moisture control is adequate enough to place resin fissure sealants.
The exact technique depends on the material used and a good application technique will increase retention, which means sealants can last longer on the teeth. [27] Generally, each quadrant is treated separately by using four-handed technique with an assistant and to follow the manufacturer's recommendations. [27] The patient should wear safety glasses for protection from chemicals and curing light. Once the patient is prepared, the surface of the tooth must be cleaned to allow maximum contact of the etch and the dental sealant with the enamel surface. A rubber dam may be used to prevent saliva from contaminating the intended site to be sealed, although often these are not used, especially for younger children. Moisture control is more of an issue with resin based sealants than with glass ionomer sealants. The surface is cleaned and dried.
Resin sealants require a phosphoric acid solution ("etch") to create microscopic porosity into which the sealant material can flow thereby increasing retention, increasing surface area and improving the strength of the bond between the sealant and the tooth surface. [28] Etching time varies from 15 to 60 seconds, depending on the product. After that, the tooth must be rinsed and dried thoroughly for 15 to 20 seconds. Chalky appearance on the dried tooth means the tooth has been properly etched. If the tooth does not have this chalky appearance, the etching process must be repeated. The sealant is then applied to the tooth by carefully placing the sealant material into the prepared pits and fissures by using a disposable instrument provided by the manufacturer. Overfilling on the tooth should be prevented to minimize occlusal adjustment. The material is left for 10 seconds after the placement prior to curing to allow optimum penetration of the sealant material into the pores created by the etching procedure. Finally, the sealant is hardened by a curing light, which usually takes 20 to 30 seconds. Glass ionomer does not require light curing, however it will set faster with the usage of a curing light. [29]
Resin-based sealants require an absolutely dry surface until polymerization is complete, so it is essential to avoid salivary contamination of the sealant site. A rubber dam or cotton roll isolation technique can be used to isolate the sealant site from saliva which is the common reason for sealant failure. Glass ionomer sealants have the advantage of not needing a dry field to be effective. In fact, the application procedure for glass ionomers can involve pressing a saliva-moistened finger onto the occlusal surface to push the sealant material into the pits and fissures.
Compared to a typical dental filling, where an injection of local anesthetic and the use of a dental drill may be involved, the application of dental sealants is significantly less invasive and generally considered quick and easy. The procedure is entirely painless, although a minor level of discomfort may be experienced by the patient. The etching gel may temporarily leave a sour taste in the mouth.
Pits and fissure sealants are used as effective controls in preventing caries. Sealants create a barrier which removes the biofilm from the occlusal surface. There are 4 sealant materials that can be used for the purpose of sealing pits and fissures. The materials are: [30]
Resin-based sealant
Glass-ionomer (GI)
Polyacid-modified resin sealants
Resin-modified glass ionomer sealants
Historically methods such as; zinc phosphate cement, mechanical fissure eradication, prophylactic odontotomy, or chemical treatment with silver nitrate, were used to seal pits and fissures. These techniques are no longer used in modern-day practice. Placement techniques for sealants rely on the type of material being used. However a common factor for all is that moisture control must be achieved. The maintenance of moisture control increases the treatment time and could be counter productive. [31]
For partially erupted teeth which are difficult to isolate some will use GIC (doesn't need etching) as an interim option. GIC may have an advantage of fluoride release.
In the US, 42% of children aged 6–11 and 48% of adolescents aged 12–19 had fissure sealants on permanent teeth during 2011–2016. [32]
In Greece, in a study from 2011, 8.3% of 12 year olds and only 8% of 15 year olds had at least one dental sealant on a molar tooth. When sealants were applied, DMFS scores were reduced by 11% in the 12 year olds and 24% in the 15 year olds. [33]
In other European countries, such as Portugal, a study has shown that over half (58.8%) of adolescents had a fissure sealant applied on at least one tooth. [34]
In Denmark, 66% of 15-year-old children had at least one sealed molar. [35]
In the UK in 2003, 13% of 8 year olds, 25% of 12 year olds and 30% of 15 year olds had at least one fissure sealant. [36] In Ireland, the rates were 47%, 70% and 69% comparatively. [37]
Around 25% of Japanese children have at least one sealed molar. [38]
A study surveying fissure sealants and dental caries in primary school girls in Saudi Arabia in 2017 found that only 1.3% of the children had at least 1 fissure sealant applied, [39] but in another study, the overall figure was 9%. [40]
Dental sealants have been around us for a very long time and have been proven in research to be a safe and effective technique for preventing dental caries, especially on occlusal surfaces where teeth are particularly susceptible to decay. [41] Through acting as a physical barrier to food and bacteria, dental sealant can prevent food from sticking to grooves in teeth and providing a place for bacteria to colonize. This is how dental sealants prevent that initial carious lesion. [42] The materials used are resins, glass ionomers and hybrids; the effect of the materials used and retention rate depend on the type of material you use. [43] But they are all effective in doing what they are used for, which is to prevent caries. Additionally, proper application, such as the tooth preparation, acid etch and adhesive also needs to be considered, otherwise, if they are applied incorrectly, it might resulted in unexpected and unfavorable clinical outcomes. [44]
[B]ased on current evidence, the ADA does not believe there is a basis for health concerns relative to BPA exposure from any dental material.
More research is needed into the extent of any dental exposure (to bisphenol A) and into the general effects of Bisphenol A exposure, but as the majority of sealants and filling materials only contain Bis-GMA, there will be no resultant oestrogenic effect from using these materials.
Tooth decay, also known as cavities or caries, is the breakdown of teeth due to acids produced by bacteria. The cavities may be a number of different colors, from yellow to black. Symptoms may include pain and difficulty eating. Complications may include inflammation of the tissue around the tooth, tooth loss and infection or abscess formation. Tooth regeneration is an on-going stem cell based field of study that is trying to reverse the effects of decay, unlike most current methods which only try to make dealing with the effects easier.
Dental products are specially fabricated materials, designed for use in dentistry. There are many different types of dental products, and their characteristics vary according to their intended purpose.
A bridge is a fixed dental restoration used to replace one or more missing teeth by joining an artificial tooth definitively to adjacent teeth or dental implants.
Dental restoration, dental fillings, or simply fillings are treatments used to restore the function, integrity, and morphology of missing tooth structure resulting from caries or external trauma as well as to the replacement of such structure supported by dental implants. They are of two broad types—direct and indirect—and are further classified by location and size. A root canal filling, for example, is a restorative technique used to fill the space where the dental pulp normally resides.
In dentistry, a crown or a dental cap is a type of dental restoration that completely caps or encircles a tooth or dental implant. A crown may be needed when a large dental cavity threatens the health of a tooth. Some dentists will also finish root canal treatment by covering the exposed tooth with a crown. A crown is typically bonded to the tooth by dental cement. They can be made from various materials, which are usually fabricated using indirect methods. Crowns are used to improve the strength or appearance of teeth and to halt deterioration. While beneficial to dental health, the procedure and materials can be costly.
Dental composite resins are dental cements made of synthetic resins. Synthetic resins evolved as restorative materials since they were insoluble, of good tooth-like appearance, insensitive to dehydration, easy to manipulate and inexpensive. Composite resins are most commonly composed of Bis-GMA and other dimethacrylate monomers, a filler material such as silica and in most applications, a photoinitiator. Dimethylglyoxime is also commonly added to achieve certain physical properties such as flow-ability. Further tailoring of physical properties is achieved by formulating unique concentrations of each constituent.
Abrasion is the non-carious, mechanical wear of tooth from interaction with objects other than tooth-tooth contact. It most commonly affects the premolars and canines, usually along the cervical margins. Based on clinical surveys, studies have shown that abrasion is the most common but not the sole aetiological factor for development of non-carious cervical lesions (NCCL) and is most frequently caused by incorrect toothbrushing technique.
In dentistry, inlays and onlays are used to fill cavities, and then cemented in place in the tooth. This is an alternative to a direct restoration, made out of composite, amalgam or glass ionomer, that is built up within the mouth.
A glass ionomer cement (GIC) is a dental restorative material used in dentistry as a filling material and luting cement, including for orthodontic bracket attachment. Glass-ionomer cements are based on the reaction of silicate glass-powder and polyacrylic acid, an ionomer. Occasionally water is used instead of an acid, altering the properties of the material and its uses. This reaction produces a powdered cement of glass particles surrounded by matrix of fluoride elements and is known chemically as glass polyalkenoate. There are other forms of similar reactions which can take place, for example, when using an aqueous solution of acrylic/itaconic copolymer with tartaric acid, this results in a glass-ionomer in liquid form. An aqueous solution of maleic acid polymer or maleic/acrylic copolymer with tartaric acid can also be used to form a glass-ionomer in liquid form. Tartaric acid plays a significant part in controlling the setting characteristics of the material. Glass-ionomer based hybrids incorporate another dental material, for example resin-modified glass ionomer cements (RMGIC) and compomers.
Dens evaginatus is a rare odontogenic developmental anomaly that is found in teeth where the outer surface appears to form an extra bump or cusp.
A luting agent is a dental cement connecting the underlying tooth structure to a fixed prosthesis. To lute means to glue two different structures together. There are two major purposes of luting agents in dentistry – to secure a cast restoration in fixed prosthodontics, and to keep orthodontic bands and appliances in situ.
Fluoride varnish is a highly concentrated form of fluoride that is applied to the tooth's surface by a dentist, dental hygienist or other dental professional, as a type of topical fluoride therapy. It is not a permanent varnish but due to its adherent nature it is able to stay in contact with the tooth surface for several hours. It may be applied to the enamel, dentine or cementum of the tooth and can be used to help prevent decay, remineralise the tooth surface and to treat dentine hypersensitivity. There are more than 30 fluoride-containing varnish products on the market today, and they have varying compositions and delivery systems. These compositional differences lead to widely variable pharmacokinetics, the effects of which remain largely untested clinically.
Dental cements have a wide range of dental and orthodontic applications. Common uses include temporary restoration of teeth, cavity linings to provide pulpal protection, sedation or insulation and cementing fixed prosthodontic appliances. Recent uses of dental cement also include two-photon calcium imaging of neuronal activity in brains of animal models in basic experimental neuroscience.
Tooth remineralization is the natural repair process for non-cavitated tooth lesions, in which calcium, phosphate and sometimes fluoride ions are deposited into crystal voids in demineralised enamel. Remineralization can contribute towards restoring strength and function within tooth structure.
Minimal intervention dentistry is a modern dental practice designed around the principal aim of preservation of as much of the natural tooth structure as possible. It uses a disease-centric philosophy that directs attention to first control and management of the disease that causes tooth decay—dental caries—and then to relief of the residual symptoms it has left behind—the decayed teeth. The approach uses similar principles for prevention of future caries, and is intended to be a complete management solution for tooth decay.
Enamel hypoplasia is a defect of the teeth in which the enamel is deficient in quantity, caused by defective enamel matrix formation during enamel development, as a result of inherited and acquired systemic condition(s). It can be identified as missing tooth structure and may manifest as pits or grooves in the crown of the affected teeth, and in extreme cases, some portions of the crown of the tooth may have no enamel, exposing the dentin. It may be generalized across the dentition or localized to a few teeth. Defects are categorized by shape or location. Common categories are pit-form, plane-form, linear-form, and localised enamel hypoplasia. Hypoplastic lesions are found in areas of the teeth where the enamel was being actively formed during a systemic or local disturbance. Since the formation of enamel extends over a long period of time, defects may be confined to one well-defined area of the affected teeth. Knowledge of chronological development of deciduous and permanent teeth makes it possible to determine the approximate time at which the developmental disturbance occurred. Enamel hypoplasia varies substantially among populations and can be used to infer health and behavioural impacts from the past. Defects have also been found in a variety of non-human animals.
Dental compomers, also known as polyacid-modified resin composite, are used in dentistry as a filling material. They were introduced in the early 1990s as a hybrid of two other dental materials, dental composites and glass ionomer cement, in an effort to combine their desirable properties: aesthetics for dental composites and the fluoride releasing ability for glass ionomer cements.
Tooth pathology is any condition of the teeth that can be congenital or acquired. Sometimes a congenital tooth disease is called a tooth abnormality. These are among the most common diseases in humans The prevention, diagnosis, treatment and rehabilitation of these diseases are the base to the dentistry profession, in which are dentists and dental hygienists, and its sub-specialties, such as oral medicine, oral and maxillofacial surgery, and endodontics. Tooth pathology is usually separated from other types of dental issues, including enamel hypoplasia and tooth wear.
Molar incisor hypomineralisation (MIH) is a type of enamel defect affecting, as the name suggests, the first molars and incisors in the permanent dentition. MIH is considered a worldwide problem with a global prevalence of 12.9% and is usually identified in children under 10 years old. This developmental condition is caused by the lack of mineralisation of enamel during its maturation phase, due to interruption to the function of ameloblasts. Peri- and post-natal factors including premature birth, certain medical conditions, fever and antibiotic use have been found to be associated with development of MIH. Recent studies have suggested the role of genetics and/or epigenetic changes to be contributors of MIH development. However, further studies on the aetiology of MIH are required because it is believed to be multifactorial.
Atraumatic restorative treatment (ART) is a method for cleaning out tooth decay from teeth using only hand instruments and placing a filling. It does not use rotary dental instruments to prepare the tooth and can be performed in settings with no access to dental equipment. No drilling or local anaesthetic injections are required. ART is considered a conservative approach, not only because it removes the decayed tissue with hand instruments, avoiding removing more tissue necessary which preserves as much tooth structure as possible, but also because it avoids pulp irritation and minimises patient discomfort. ART can be used for small, medium and deep cavities caused by dental caries.