Avulsed Anterior Permanent Tooth Replaced by Fixed Functional Interim Prosthesis with Natural Crown: A Case Report Interim Prosthesis with Natural Crown: A Case Report

The  incidence  of  trauma  to  the  anterior  teeth  is  a  common  occurrence  in  children.  From  the  very  moment  the  child  tries  to  walk  erect  independently,  the  susceptibility  of  the  child’s  anterior  teeth  getting  injured  begins.  Avulsion  (a  type  of  traumatic  injury)  is  the  complete  loss  of  the  tooth  from  its  socket. Various  treatment  modalities  are  available  to  treat  such  accidents.  The  tooth  can  be  replanted  back  or  replaced  by  a  prosthesis, it  depends  upon  the  extraoral  drytime  and  the  stage  of  development  of  root  of  the  avulsed  tooth.  The  present  case-report  describes  the  way  in  which  an  avulsed  permanent  maxillary  central  incisor  of  a  12  year  old  boy   was   replaced  aesthetically, and  satisfactorily  after  1  month  of  avulsion  by  means  of  a  biological  fixed  functional  prosthesis  ( a  modified   “Hollywood Bridge” )  where  the  crown  of  the  avulsed  tooth  was  used  as  a  pontic  and  stainless  steel  wires  and  bands  were  used  to  fix  the  prosthesis  in  the  mouth as  an  interim  treatment  option.


INTRODUCTION
Trauma to the anterior teeth is relatively common in children. 1 Dental injuries are highly prevalent between 7 and 12 years of age wherein males are the most commonly affected. Avulsion is one of the most serious dental injuries, considering that it is the complete detachment of a tooth from its socket. 2 According to a previous report, 10% of the population has experienced some kind of dental trauma, of which 0.5-16% accounts to avulsion of permanent teeth. [3][4][5][6][7] The etiology of tooth avulsion in permanent dentition includes falls, fights, sport injuries, automobile accidents, and child abuse. 8 The maxillary incisors are the most commonly affected in cases of increased overjet and incompetent lips, which are the potential etiological factors of avulsion. 8 Treatment planning depends on the extraoral drytime and the stage of development of root of the avulsed tooth. 1 The treatment of choice for an avulsed tooth is immediate reimplantation, although it is not always possible to perform this treatment. 9 If reimplantation cannot be performed, prosthetic management is advised. 1 Prosthetic management includes treatment options such as fabrication of a fixed partial denture (e.g., Maryland bridge or a fiber-reinforced resincomposite bridge) or a removable partial denture to replace the missing permanent tooth. 2,5,6 Moreover, fixed functional prosthesis, which is also known as "Hollywood Bridge" can be an alternative choice of treatment to replace a missing tooth. It comprises the artificial tooth (pontic) being attached to stainless steel wires that are soldered to bands adapted around the molars. 3 The current case report elaborates a way of replacing a missing permanent central incisor by means of a modified "Hollywood Bridge." In such approach, the crown of the avulsed tooth was separated from its root and then attached to stainless steel wires to serve as an interim treatment option.

CASE REPORT
A 12-year-old boy reported to the Department of Pedodontics and Preventive Dentistry in Guru Nanak Institute of Dental Sciences and Research, Kolkata, with a chief complaint of missing tooth in the upper front tooth region. As stated by the parent, the child lost his tooth because he fell to the ground a month before. Since the incident, the parent kept the tooth in a piece of paper and wished that the tooth be placed back in its usual place. Intraoral examination revealed the absence of the maxillary left permanent central incisor (21) and completely healed socket and soft tissue ( Figure 1). Furthermore, a radiolucent bony socket of the concerned avulsed tooth was observed during radiological investigation (IOPAR) (Figure 2). The patient had a moderate oral hygiene status. Medical history was noncontributory. A fixed functional prosthesis (modified biological "Hollywood bridge") was decided to be fabricated with the decoronated crown of the avulsed tooth serving as the pontic for the replacement of the missing tooth, thereby fulfilling the esthetic and psychological needs of the patient. The treatment plan was explained to the patient, and an informed consent was obtained subsequently.
After proper oral prophylaxis was applied, impressions of both arches were acquired to create the diagnostic cast ( Figure 3). Orthodontic bands (0.005-inch thickness and 0.180-inch width) were adapted on teeth 16 and 26, and then an alginate impression of the upper arch was obtained and poured with dental stones to create the working cast. Before the avulsed tooth was decoronated, the tooth was properly cleaned, stored, and sterilized by immersing in 0.9 N of sodium hydroxide for 2 hours and then autoclaving at 121°C for 15 minutes. 10 Then, a tapered fissure diamond bar was selected for a complete decoronation 5 of the avulsed tooth using an air rotor handpiece. The crown was completely separated from the root. Throughout the entire process, the normal contour of the cementoenamel junction was maintained (Figure      ). The decoronated crown was now placed on the maxillary cast in its missing place to check if any adjustments in its dimensions were further needed ( Figure 5). A groove was created on the middle third of the palatal surface of the crown with the tapered fissure bur to retain the wire (to be used to reinforce the appliance) on to the crown ( Figure 6). A 19 gage stainless steel wire was then molded and adapted to the shape of the maxillary arch. Thereafter, the crown was placed in its desired place, and the created palatal groove was made to contact the anterior portion of the wire, ensuring good adaptation between the tooth and the wire. The free ends of the wire were soldered to the corresponding molar bands. The palatal surface was etched with 37% phosphoric acid and applied with a bonding agent (Figure 7). Furthermore, a light-cure composite resin (Ivoclar Vivadent) was added in an increasing amount between the palatal groove and the contacted portion of the wire as well as on top of it and then light-cured for 30 seconds. The appliance was then removed from the cast for trimming, finishing, and polishing. Afterward, the appliance was fitted in the patient's mouth and finally cemented in place by using Type 1 glass ionomer cement (Figure 8). The placement was checked for any presence of occlusion and adjusted as necessary. The final outcome was a well-adapted prosthesis with excellent esthetics. The patient was consistently followed up at 3 months interval and advised to wear the appliance until 18 years of age. Thereafter, removal of the appliance followed by anterior maxillary implant placement in place of the missing upper left permanent central incisor, was advised. The appliance was in good condition after 1 year of follow-up (Figure 9).

DISCUSSION
Replacement of an avulsed tooth in a growing child is challenging for the clinicians. The primary goal in treating an avulsed tooth is its timely reimplantation. In the present case, the patient sought for consultation after 1 month of avulsion when the soft tissue was already completely healed. Hence, the avulsed tooth could no longer be reimplanted.
If reimplantation cannot be perfor med, prosthetic management is advised. 1 Various treatment options are available for prosthetic replacement. Removable partial dentures are often the first line of treatment in a growing pediatric patient until the dimensions of the alveolar bone have become stable and the eruption of permanent teeth has completed; however, child's compliance to wear the prosthesis is questionable. 2 Another option is the Maryland bridge, which consists of an artificial crown attached to the adjacent teeth with the aid of wing-like porous metal retainers; however, the metal framework can sometimes pose an unesthetic appearance and also reportedly lowers bond strength between the enamel and the metal, making it a less favorable option. 2 Cantilever-fixed partial dentures are also undesirable candidates for replacing missing avulsed permanent anterior teeth because they compromise the support aside from applying additional torsion on the abutment. 2 Fiber-reinforced resin-composite bridges can result in excellent esthetics in terms of replacing missing teeth, but their inability to withstand heavy masticatory load and problems in maintaining oral hygiene can downgrade their status as a treatment option. 2 Fixed functional prosthesis can be an alternative choice of treatment for tooth replacement. Also known as "Hollywood Bridge," it comprises the artificial tooth (pontic) being attached to stainless steel wires that are soldered to bands adapted around the molars. In the present case, "Hollywood Bridge" was modified by using the crown of the decoronated avulsed tooth as a pontic instead of any artificial tooth. Advantages of this prosthesis involve no compromise of healthy tooth structure of any adjacent or opposite teeth, given that no tooth preparation is needed. It has also adequate strength to withstand mastication forces and other associated functional movements. It serves both functional and esthetic purposes. Patient compliance Figure 7. A 19 gage stainless steel wire Orthodontic bands were adapted on teeth 16 and 26, an alginate impression was obtained to make the working cast, and the crown of the avulsed tooth was placed on the working cast.  is nil, considering that the appliance is fixed in its type. It is a simple, noninvasive, and also economical treatment procedure. The only disadvantage is that the incorporation of bands on the permanent first molars may hamper the transverse maxillary growth. 11 It is a favorable interim option for replacing lost anterior teeth in a growing child wherein ossification of midpalatine suture has not occurred, 12 thereby minimally affecting the maxillary transverse growth. If this procedure is performed at the right time, that is, before the ossification of the midpalatin suture, 11,12 the labiopalatal alveolar dimensions can be preserved for years while at the same time allowing for extra vertical growth, making restoration possible later with an implant.

CONCLUSION
Our case suggests a temporary treatment option for the functional and esthetic replacement of a missing anterior tooth in children. The modified biological "Hollywood Bridge" prosthesis can be fabricated easily, repaired, and removed from the mouth without any damage to the sound tooth structure. Aside from being economical, it can maintain the place for future implant or any permanent prosthesis.