The term splint has been defined by American Association of Endodontics as a rigid or flexible device or compound used to support , protect or immobilize teeth that have been loosened, replanted, fractured or subjected to certain endodontic surgical procedures.
The design and concept of splinting traumatized teeth evolved from the splints used for immobilization of jaw bones, that required rigid splints for a longer period of time.Until late 1970, rigid splints were used ,which did allow physiological tooth movement and were also associated with greater frequency of pulp necrosis and pulp canal obliteration.Semi rigid splinting is therefore a common and preferred method that allows controlled passive mobilization of the traumatized tooth.
A basic requirement is that the splint should be passive and semi rigid whilst maintaining physiological tooth mobility.Other requirements of splints are given in figure below.
During splinting ,the tooth is immobilized by fixing it to the adjacent unaffected teeth.Generally,traumatized tooth is fixed to just one tooth on the adjacent side,since evidence does not indicate an additional benefit if the splint is extended to more than one tooth.It is also noted that , if the distance between the traumatized toooth and its neighbours is increased, it results in more elastic deviation of the splint and reduced controlled immobilization.This means that splinting effect may not be the same between spaced arches and non-spaced arches.
TYPES OF SPLINTS: Splints used for immobilizing a traumatized tooth can be classified either as :
RIGID:
-Suture splints
-Arch bar splints
-Acrylic cap splints
-Composite splints
SEMI-RIGID:
-Orthodontic wire and bracket splints
-Wire and composite splints
-Fibre splints
-Titanium trauma splints
1-Suture splints: These are used when there are multiple missing teeth or during the mixed dentition period when routine devices can not be placed.They use soft wire that is fixed around the teeth as figure of eight or continuous loop.This type of fixation is used when there is need for short term intermaxillary fixation.This type of fixation is used when there is need for short-term fixation.
The disadvantage of this splint is that steel wire breaks easily on tightning and the chance of it becoming loose is high.Maintaining oral hygiene is also very difficult and gingivitis is common.Since they have short life,they are recommended to be used only for few days.
2-Arch bar splint: Arch bar splints were first introduced by hammond in 1870s as splints for maxillary and mandibular fractures.They consist of a metal arch bar bent in to the shape of an arch which is secured in place with ligature wires.
The main disadvantage of this type of splint is that it is rigid and hence its use, in the case of dental injuries, is limited.In addition, where the arch bar is not bent in to correct shape, it can exert orthodontic forces on the tooth.It has also been noted that arch bar splints can become loose and rest on marginal gingivae causing mechanical irritation.
3-Acrylic cap splints:This splint is made of acrylic material and has been used to fix luxated teeth with alveolar fractures.It can cause great inconveniance to the patient if prepared directly over the teeth,therefore it is recommended that it be fabricated on a model.
But that too has disadvantage ,as it requires an impression, which is contraindicated in cases of luxation.Therefore it is not routinely used for immobilization of isolated dental trauma.
4-Composite splints: These are fabricated from a band of composite material which is placed directly on the labial surface of the teeth to be splinted together.The resin is applied continuously to the labial surface of the crowns, using a syringe, connecting all the teeth to be splinted.Such splints are easy to prepare but they tend to break easily in the interdental region when placed under occlusal load, and therefore are not recommended for long term splinting.
It was noted that composite splints produced an increased irritation to gingiva compared to the use of wire and composite, an orthodontic bracket splint or the titanium trauma splint.
5-Orthodontic wire and bracket splints: These splints consists of brackets bonded to the middle third of the labial surface of the tooth with light curing composite resin.A 0.3 mm soft wire is then braided from bracket to bracket to connect all the teeth.
Bracket splints are found to be more irritating to the lips compared to the wire and composite, composite or titanium trauma splints.Care should be taken to avoid the application of orthodontic forces on the teeth .Orthodontic wires are never passive and generate forces that range up to 27.33*0.01 N, which may result in tipping of the incisors.The advantage of an orthodontic splint is that simultaneous tooth movement and tooth repositioning is possible when needed.It should also be noted that rectangular wires or wires made of NiTi are not recommended, since the force developed by these wires is higher than when round/square stainless steel or cobalt-chrome wires are used. This may be due to higher elasticity of the NiTi wires.
6-Wire and composite splints: This was introduced by O'Riordan et al, who used a thin flexible wire of diameter 0.3-0.4 mm as a splint.It is semi rigid secured by light cured composite resin.The wire and composite splint is the most favoured and routinely used splint for immobilizing a traumatized tooth, as it meets most of the demands of modern tooth fixation.This splint can be used in almost all types of tooth injuries.The composite is placed over the wire on the labial portion without extending in to interdental area.
The amount of composite that covers the wire will influence the rigidity of the splint,since it reduces the free and deformable section of the wire.The diameter of the wire used also determines the rigidity of the splint.The less the diameter of the wire used, the more flexible the splint.Thus a wire of diameter 0.3-0.4 mm was found to be more flexible than a 0.5 mm wire.The only situation where wire and composite splints can not be used are on teeth with artificial crowns, large fillings where etching of the surface is not possible, teeth restored with porcelain veneer, or where the adjacent teeth are absent .It may be difficult but not impossible to place this splint on teeth with smaller crowns.
Bonding between the wire and composite was a concern.In a study, to evaluate the optimal method of enhancing the wire-composite bond strength of dental splints, they found the bond between the stainless steel wire and the composite could be improved by sandblasting the wire.
7-Fibre splints:The main advantage of the fibre splint is that it does not require any laboratory assistance and is bonded directly on to the teeth.It has good strength, less volume and is aesthetic and repairable.Fibre- reinforced composites are resin based materials containing fibres aimed at enhancing their physical properties.The fibres used are heterogenous and varied , depending on the nature of the fibre, the geometrical arrangement of the fibres and the overlying resin material.The fibres commonly used are glass, ultrahigh strength polyethylene fibre and kevlar fibres.The properties of the splint depend on the pattern of arrangement of the fibres (unidirectional, meshwork design or wooven arrangement).Key factors which influence the physical properties of fibre-reinforced structures are:
-Fibre loading within the restoration
-Effectiveness of the bond betwen the fibre resin interface
-Fibre orientation and fibre position in the restoration.
The commonly used bondable reinforced fibres in clinical practice are:
-Ultrahigh molecular weight polyethylene fibres-Ribbond (Ribbond), Connect (Kerr)
-Glass fibres- GlassSpan (GlassSpan) and Fibre Splint ML (Polydentia)
-Fibres pre-impregnated with resin- Vectris (Vivadent), StickNet (StickNet) and FibreKor(Jeneric/Pentron).
Ribbond is a biocompatible, aesthetic material made from polyethylene fibre, which was in use until recently.The present day splint utilizes silanated E-type glass fibres (Everstick,Stick Tech Ltd,Turku,Finland) embedded in a BISGMA matrix and surrounded by PMMA coating (interpenetrating polymer network) with good flexure strength of 1280 Mpa.
8-Titanium trauma splints (TTS)
The TTS is a new device developed by von Arx et al.It is made of pure titanium and is 0.2 mm thick and 2.8 mm in width (Medartis AG,Basel,Switzerland).It has rhomboid mesh structure , making it flexible, to allow for physiological tooth movement.It can easily be adapted to the contour of the dental arch with fingers without the need of additional pliers.It is easy to cut with any cutting instrument .A TTS splint of about 52mm is required to extend the splint from canine to canine.As it is thin and flexible it can easily be adapted to the desired position.A thin layer of flowable composite is placed in to rhomboid opening of the splint after the application of etch and bonding agent.
The splint placement comparison study by von Arx et al demonstrated that titanium trauma splints are the easiest and least time comsuming to apply (8.5 +/- 0.76 min) compared to the wire and composite splint (10.1+/- 1.29 min) or the bracket splint (13.1+/- 0.94min). The amount of composite used to bond the splint to the tooth is small, within the rhomboid opening, making it easier to remove the splint after its use.It was also observed that TTS was comfertable for the patient because it was less bulky and did not hinder speech or oral hygiene practice.
