Bicuspidization: A Case Report

INTRODUCTION

The increased awareness and desire of patients to maintain their dentition has forced dentists to conserve the teeth in the mouth which otherwise are planned to be removed. Due to anatomical limitations, furcations often prevent adequate plaque control which may eventually result in tooth loss. Furcation invasion can be observed in molar and premolar teeth in both the horizontal and vertical dimensions. The management and treatment of mandibular molars exhibiting furcation invasions have always been a challenge. The treatment involves combining restorative dentistry, endodontics and periodontics. These teeth can be retained and used as independent units of mastication or as abutments in simple fixed bridges. Severe periodontal involvement will lead to loss of the tooth, unless these defects are repaired or eliminated, and health of the tissue restored. Periodontally compromised teeth with severe bone loss at the furcation area may still be retained by tooth resection.

The term "tooth resection" denotes the excision and removal of any segment of the tooth or a root with or without its accompanying crown portion. Various resection procedures have been described such as: root amputation, hemisection, radisection and bisection. Hemisection denotes removal or separation ofroot with its accompanying crown portion of mandibular molars. Radisection is a newer terminology for removal of roots of maxillary molars. Bisection / bicuspidization/root separation is a procedure in which the clinician splits the mandibular molar vertically through the furcation, without removing either half, leaving two separate roots that then are treated as bicuspids .^1,2

Several authors have listed the following indications and contraindications for tooth resection^3-7 :

INDICATIONS:

1) Periodontal indications:

• Severe bone loss affecting one or more roots untreatable with regenerativeprocedures.
• Class II or III furcation invasions or involvements
• Severe recession or dehiscence of a root

2) Endodontic or conservative indications

• Inability to successfully treat and fill a canal
• Root fracture or root perforation
• Root caries of the furcation area

3) Prosthetic indications

• Severe root proximity inadequate for a properembrasure space
• Root trunk fracture or decay with invasion of thebiological width

CONTRAINDICATIONS:

1) General contraindications to periodontal surgery:

• Systemic factors
• Poor oral hygiene

2) Factors associated with local anatomy:

• Fused roots 
• Unfavourable tissue architecture

3) Endodontic factors:

• Retained roots endodontically untreatable
• Excessive endodontic instrumentation of retainedroots
• Excessive deepening of pulp chamber floor
• Severe root resorption

4) Restorative factors:

• Internal root decay
• Presence of a cemented post in the remaining root

STRATEGIC CONSIDERATIONS:

• Ÿ Consider adjacent teeth available for conventional prosthetic restoration
• Consider removable prosthesis
• Consider implants

CASE REPORT

A 28 year old male patient reported with severe pain in the lower right posterior region of the mouth since one week. On intraoral examination 46 had a silver amalgam restoration. The tooth was tender on percussion. On probing, deep periodontal pocket was present. Intraoral periapical radiograph showed an over-hanging restoration, widening of periodontal ligament space, furcation involvement and periapical radiolucency around the mesial root.It was then decided to perform bicuspidization on 46 after endodontic treatment.

Under local anaesthesia, access opening was done, working length was determined and the canals were biomechanically prepared using step back technique. The canals were obturated with lateral condensation method and the pulp chamber was filled with amalgam to obtain a good seal and allow interproximal area to be properly contoured during surgical separation.

On the subsequent visit under local anaesthesia, the vertical cut method was used to separate the crown .A long shank tapered fissure carbide bur was used to make vertical cut toward the bifurcation area. The furcation area was trimmed to ensure that no residual debris were present which could cause further periodontal irritation. Scaling and root planing of the root surfaces was done after gaining accessibility once the roots were separated. The occlusal table of both the halves were minimized to redirect the forces along the long axis of each root.Each half was shaped into a bicuspid and separate crowns were placed.

DISCUSSION

Like any other clinical procedure the success depends on good case selection prognosis and treatment. Farshchian and Kaiser have reported the success of a molar bisection with subsequent bicuspidization depends on three factors ⁸:

1. Stability of, and adequate bone support for, the individual tooth sections

2. Absence of severe root fluting of the distal aspectof the mesial root or mesial aspect of the distal root.

3. Adequate separation of the mesial and distal roots,to enable the creation of an acceptable embrasure for effective oral hygiene.

According to Newell the advantage of the amputation, hemisection or bisection is the retention of some or the entire tooth ⁹. However, the crown must undergo restorative management. It is important to consider the following factors before deciding to undertake any of the root separation and resection or bicuspidization procedures.

• Advanced bone loss around furcation area and acceptable level of bone around the remaining roots
• Severe destruction of tooth structure in furcation area. 
• Angulations and position of the tooth in the arch.A molar that is buccally, lingually, mesially or distally titled, cannot be separated.
• Divergence of the roots - teeth with divergent roots is easier to resect. Closely approximated or fused roots are poor candidates.
• Length and curvature of roots - long and straight roots are more favourable for root separation than short, conical roots
• Feasibility of endodontics and restorative dentistry in the roots.

Root separation has been used successfully to retain teeth with furcation involvement. However, there are few disadvantages associated with it. As with any surgical procedure; it can cause pain and anxiety. When confronted with restoring two separated roots of mandibular molar, it is very important to create sufficient inter-radicular space (perhaps by orthodontics) if the root sufficiently diverge.When two individual crowns are fabricated, the interproximal area should be enlarged to allow the easy passage of a proxabrush. This can be accomplished by under-contouring the proximal aspects and locating the contact point (or solder joint) in a more coronal location.

Unfortunately, a restoration can contribute to periodontal destruction, if the margins are defective or if non-occlusal surfaces do not have physiologic form. Also, an improperly shaped occlusal contact area may convert acceptable forces into destructive forces and predispose the tooth to trauma from occlusion and ultimate failure of root separation and resection^10,11 . Hence, during treatment, occlusal contacts were reduced in size and repositioned more favourably. Lateral forces were reduced by making cuspal inclines less steep and eliminating balancing incline contacts.

CONCLUSION

The prognosis for bicuspidization is the same as for routine endodontic procedures provided that the case selection has been performed correctly, and the restoration is of an acceptable design relative to the occlusal and periodontal needs of the patient. Hence, bicuspidization should be considered as other treatment options for the dental surgeons, determined to retain and not remove the natural teeth.