Temporary crown

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A temporary crown (white) on a tooth after endodontic therapy Temporary crown a.jpg
A temporary crown (white) on a tooth after endodontic therapy

A temporary crown (provisional crown, interim crown) is a temporary (short-term) crown used in dentistry. Like other interim restorations, it serves until a final (definitive) restoration can be inserted. Usually the temporary crown is constructed from acrylic resins (monomethacrylate-based/polymethacrylate-based) or, chemical-cure/light cure composite (dimethacrylate-based), although alternative systems using aluminium crown forms are occasionally used. [1] Temporary crowns function to protect the tooth, prevent teeth shifting, provide cosmetics, shape the gum tissue properly, and prevent sensitivity. [2]

Contents

Function

The functions of temporary crowns are:

Provisional restorations offer dental aesthetics purposes, especially for anterior teeth. A patient can evaluate the aesthetic of the temporary crown if that is to be changed in the definitive restoration.
Overeruption of opposing teeth and drifting of adjacent teeth can be prevented by providing provisional restoration. Masticatory function for posterior teeth can be restored as well.
These include whether sufficient tooth has been prepared to accommodate the definitive restoration and any undercuts present will be removed. If deficiencies in the tooth prep are found, these can be rectified and the temporary crowns can be relined or remade.
Exposed dentinal tubules in vital teeth can be covered with temporary crowns to prevent any dentinal fluid movement
Temporary crowns block bacteria entry to prevent pulpal inflammation and maintain a good coronal seal to the root canal filling. [3] [4]

Preformed crowns

Problems

  1. Polycarbonate crowns [3]

A tooth-coloured shell that is slightly larger than the tooth preparation is selected and is reduced to the correct dimensions using a bur until it seats fully on the tooth preparation without bedding into the gingiva. Petroleum jelly is smeared over the tooth and acrylic resin is spread over the fitting surface of the crown. The shell is removed once the resin has polymerised and the restoration is trimmed until fit is satisfactory.

2. Plastic crowns [3] Clear plastic crowns can be selected and trimmed with a scissors without traumatising the gingiva. Small holes can be made on the canine tips, incisal angles and cusps with a probe before filling crowns with acrylic resin to reduce risk of bubbles formation. Once the resin has set, the restoration can be checked for occlusion and margins before being cemented in.

3. Composite crowns [3] Preformed malleable composite crowns are soft and easily moulded to the tooth in situ. They can be partially cured for two to three seconds in the mouth and removed to be fully cured outside the mouth. Final check for occlusion, fit and margins can be carried out prior to cementing provisional restoration.

4. Metal-based crowns [3] When a permanent crown needs replacement or sectioning for caries removal, the original crown can be modified and used as a temporary restoration. The crown can be relined with bis-acrylic composite resin and cemented on temporarily.

Custom-formed resin replica temporary crown

Chairside temporary crowns can be made in the mouth using a suitable mould. It is extremely useful in cases where the tooth to be prepared is structurally intact. The material used is usually that of a bis-acrylic composite material (e.g. ProTemp), or one which consists of the higher acrylics, usually a mixture of poly(ethyl methacrylate) and poly(isobutyl methacrylate). [5] Custom-formed provisional crowns allow for shaping of the gingival tissues in order to achieve a satisfactory emergence profile of the definitive restoration. This is indicated particularly when restoring bone-level dental implants. [3]

How to make a custom-formed provisional restoration: [3]

  1. A sectional impression of the tooth to be prepared is made.
  2. Prepare the tooth for the chosen design of restoration.
  3. A thin layer of petroleum jelly can be smeared onto the preparation to facilitate the removal of the provisional restoration from the tooth once the material is set
  4. Syringe the bis-acrylic composite resin into the sectional impression of the tooth that has been prepared, and relocate the impression in the mouth. Ensure that the impression is fully seated over the teeth – an obvious click can often be felt as the impression passes over the bulbosity of the remaining teeth.
  5. Remove the impression before complete polymerisation of the bis-acryl resin. At this stage, the resin will feel rubber.
  6. Once removed from the mouth or impression, any material flash and ledges can be removed with a high speed diamond bur or abrasive polishing discs. The marginal fit and occlusion are checked with the provisional restoration in situ and adjusted if necessary, ideally outside of the mouth.
  7. The provisional restoration can then be cemented with a temporary luting cement.
  8. Remove excess cement from the margins, carefully using dental floss interproximally.

Cementing of the temporary restoration

An ideal provisional cement should exhibit the following characteristics: capability of retaining the provisional crown for months, but easy on removal of the temporary prosthesis; easy removal of excess cement from around the margins; good marginal seal; and compatibility with provisional restorations.[ citation needed ] Adhesive cements should be avoided as they are difficult to remove. Eugenol containing products are advantageous as they are adhesive without being difficult to remove. [6] However, eugenol has an inhibitory effect on the polymerisation of methacrylate-based resins, [7] and may potentially lead to a lower resin-dentine bond strength.

Prior to the cementation of the provisional crown, the occlusion should be checked. Any deficiencies in the provisional crown can be amended by the addition of more temporary crown and bridge material, or a light cured composite. [6]

If a temporary crown becomes de-cemented, it is important that a dentist examine the patient as overeruption of the opposing teeth may prevent accurate fitting of the final crown. [8] If a dentist cannot be seen in a timely manner, the temporary crown may be re-cemented by applying temporary cement to the temporary crown.

Materials

A systemic study found that di-methacrylate-based provisional restorations had better flexural strength and hardness than the mono-methacrylate-based ones, while, within the mono-methacrylate group, poly-methylmethacrylate showed better flexural strength than poly-ethylmethacrylate. [9]

Oral hygiene

Oral hygiene tooth brushing and flossing is crucial to prevent gingival inflammation and bleeding. Patients are advised to pull the dental floss out buccally instead of pulling back up through the contact point. This is to avoid accidentally pulling out a provisional restoration. [3]

Related Research Articles

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.

Dentures Prosthetic devices constructed to replace missing teeth

Dentures are prosthetic devices constructed to replace missing teeth, and are supported by the surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable. However, there are many denture designs, some which rely on bonding or clasping onto teeth or dental implants. There are two main categories of dentures, the distinction being whether they are used to replace missing teeth on the mandibular arch or on the maxillary arch.

Bridge (dentistry)

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.

Dental technician Technologist working on dental appliances

A dental technologist is a member of the dental team who, upon prescription from a dental clinician, constructs custom-made restorative and dental appliances.

Mouthguard

A mouthguard is a protective device for the mouth that covers the teeth and gums to prevent and reduce injury to the teeth, arches, lips and gums. "An effective mouthguard is like a ‘crash helmet’ for teeth and jaws. It also prevents the jaws coming together fully, thereby reducing the risk of jaw joint injuries and concussion." A mouthguard is most often used to prevent injury in contact sports, as a treatment for bruxism or TMD, or as part of certain dental procedures, such as tooth bleaching or sleep apnea treatment. Depending on application, it may also be called a mouth protector, mouth piece, gumshield, gumguard, nightguard, occlusal splint, bite splint, or bite plane.

Dental sealants 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 which 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.

Crown (dental restoration)

In dentistry, a crown most commonly refers to a dental cap, a type of dental restoration that completely caps or encircles a tooth or dental implant. A crown may be needed when a large cavity threatens the health of a tooth. 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

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 reasonably inexpensive. Composite resins are most commonly composed of Bis-GMA and other dimethacrylate monomers, a filler material such as silica and in most current 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.

Inlays and onlays

In dentistry, inlays and onlays are a form of indirect restoration, which means they are made outside of the mouth as a single, solid piece that fits the specific size and shape of the cavity, 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.

Veneer (dentistry)

In dentistry, a veneer is a layer of material placed over a tooth. Veneers can improve the aesthetics of a smile and protect the tooth's surface from damage.

Synthetic resins are industrially produced resins, typically viscous substances that convert into rigid polymers by the process of curing. In order to undergo curing, resins typically contain reactive end groups, such as acrylates or epoxides. Some synthetic resins have properties similar to natural plant resins, but many do not.

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.

Luting agent

A luting agent is an application of 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.

Fixed prosthodontics is the area of prosthodontics focused on permanently attached (fixed) dental prostheses. Such dental restorations, also referred to as indirect restorations, include crowns, bridges, inlays, onlays, and veneers. Prosthodontists are specialist dentists who have undertaken training recognized by academic institutions in this field. Fixed prosthodontics can be used to restore single or multiple teeth, spanning areas where teeth have been lost. In general, the main advantages of fixed prosthodontics when compared to direct restorations is the superior strength when used in large restorations, and the ability to create an aesthetic looking tooth. As with any dental restoration, principles used to determine the appropriate restoration involves consideration of the materials to be used, extent of tooth destruction, orientation and location of tooth, and condition of neighboring teeth.

A post and core crown is a type of dental restoration required where there is an inadequate amount of sound tooth tissue remaining to retain a conventional crown. A post is cemented into a prepared root canal, which retains a core restoration, which retains the final crown.

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.

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.

The Dahl effect or Dahl concept is used in dentistry where a localized appliance or localized restoration is used to increase the available interocclusal space for restorations.

Tooth mobility Medical condition

Tooth mobility is the horizontal or vertical displacement of a tooth beyond its normal physiological boundaries around the gingival area, i.e. the medical term for a loose tooth.

References

  1. Amin BM, Aras MA, Chitre V (2015). "A comparative evaluation of the marginal accuracy of crowns fabricated from four commercially available provisional materials: An in vitro study". Contemporary Clinical Dentistry. 6 (2): 161–5. doi:10.4103/0976-237X.156035. PMC   4456735 . PMID   26097348.
  2. "Temporary Crown Fell Out". 20 July 2015.
  3. 1 2 3 4 5 6 7 8 9 Advanced operative dentistry : a practical approach. Ricketts, David (David Nigel James), Bartlett, David W. Edinburgh: Elsevier. 2011. ISBN   9780702031267. OCLC   745905736.CS1 maint: others (link)
  4. Steele, J. G.; St. George, G; Ingledew, R. P.; George, G. St; Wassell, R. W. (June 2002). "Crowns and other extra-coronal restorations: Provisional restorations". British Dental Journal. 192 (11): 619–630. doi: 10.1038/sj.bdj.4801443 . ISSN   1476-5373. PMID   12108942.
  5. N., Smith, Bernard G. (2007). Planning and making crowns and bridges. Howe, Leslie C. (4th ed.). Abingdon, Oxon, UK: Informa Healthcare. ISBN   9780415398503. OCLC   70881739.
  6. 1 2 W., Bartlett, David (2007). Indirect restorations. Ricketts, David (David Nigel James). London: Quintessence. ISBN   9781850970781. OCLC   85689299.
  7. Craig's restorative dental materials. Sakaguchi, Ronald L., Powers, John M., 1946- (13th ed.). St. Louis, Mo.: Elsevier/Mosby. 2012. ISBN   9780323081085. OCLC   757994720.CS1 maint: others (link)
  8. Craddock HL, Youngson CC (2004). "A study of the incidence of overeruption and occlusal interferences in unopposed posterior teeth". British Dental Journal. 196 (6): 341–8, discussion 337. doi: 10.1038/sj.bdj.4811082 . PMID   15044991.
  9. Astudillo, Daniela; Delgado Gaete, Andrés; Bellot-Arcis, Carlos; Montiel-Company, Jose; Pascual, Agustin; Almerich-Silla, Jose (2018-02-28). "Mechanical properties of provisional dental materials: A systematic review and meta-analysis". PLOS ONE. 13 (2): e0193162. Bibcode:2018PLoSO..1393162A. doi: 10.1371/journal.pone.0193162 . PMC   5830998 . PMID   29489883.