INTRODUCTION
Hemisection (removal of one root) involves removing significantly compromised root structure and the associated coronal structure through deliberate excision.1 Because of two roots present in mandibular molars, one half of the crown and associated root is removed. Thus tooth resection procedures are used to preserve as much tooth structure as possible rather than sacrificing the whole tooth. It differs from bicuspidization, in which a separation is made between the two roots in the furcation area without removal of any root. The separated roots along with its crown part are then restored as premolars2. Selected root removal allows improved access for homecare and plaque control with resultant bone formation and reduced pocket depth.
This procedure is indicated3

 If there is severe bone loss limited to one root or involvement of a Class III furcation that could produce a stable root after hemisection.
  If the patient is unable to perform appropriate oral hygiene in the area.
  Extensive exposure of the roots because of dehiscence is another indication for excision of one root.
  Indicated for failure of an abutment within a fixed prosthesis, provided a portion of the tooth can be retained to act as the abutment for the prosthesis.
  Untreatable endodontic failure due to perforations and broken instruments.
 Vertical root fracture confined to a single root of a multirooted tooth or any severe destructive process that is confined to a single root, including caries, external root resorption and trauma.

CASE REPORT:
A 30 years old male patient reported to the department with the complaint of pain in left mandibular first molar. On examination, the tooth was tender to percussion and was grossly carious. On probing the area, there was a deep periodontal pocket around the mesial root of the tooth. On radiographic examination, furcation involvement was evident. The bony support of distal root was completely intact (Fig. 1). It was decided that the mesial root should be hemisected after completion of endodontic therapy of the tooth.

Biomechanical preparation was done with in the distal root only (Figure 2).

Hemisection of the mesial root and crown was done with a vertical cut method. After vertical incision and sulcular incision, a mucoperiosteal flap was reflected. The crown was cut with a long shank, tapered fissure carbide bur till the furcation is reached(Figure 3). Once the separation was

complete, the mesial half was extracted. The empty socket was thoroughly irrigated and the flap was sutured back into its position.
After the complete healing of the extraction socket , the crown of the remaing thooth was restored with FPD on 45,46 so as to distribute the occlusal stresses(Figure 4).

DISCUSSION:
Before selecting a tooth for hemisection, patient’s oral hygiene status, caries index and medical status should be considered. Also the accessibility of root furcation for ease of operation as well as good bone support for the remaining roots should be assessed. The furcation region is carefully smoothed, to allow proper cleansing and thus to prevent accumulation of plaque.4 Root fracture is the main cause of failure after hemisection, so occlusal modifications are required to balance the occlusal forces on the remaining root.5
Contraindications include the presence of a strong abutment tooth adjacent to the proposed hemisection, which could act as an abutment to prosthesis. The remaining root may be inoperable for the necessary root canal treatment6. Also, fusion or proximity of the roots may prevent their separation3.
Hemisection may be a suitable alternative to extraction and implant therapy and should be discussed with patients during consideration of treatment options

REFERENCE
1.  Bühler H. Survival rates of hemisected teeth: an attempt to compare them with survival rates of alloplastic implants. Int J Periodontics Restorative Dent 1994; 14(6):536–43.
2.  Shah N and Gupta YK. Endodontic Miscellany: 1. Hemisection and full coverage to relieve crowding and lingual displacement of a pulpo-periodontally involved mandibular first molar. Endodontology, Vol. 12, 2000,83-85.
3.  Weine FS. Endodontic Therapy, 5th Edition.St. Louis: Mosby; 1996.
4.  Rapoport RH, Deep P. Traumatic hemisection and restoration of a maxillary first premolar: a case report. Gen Dent 2003; 51(4):340–2.
5.  Kryshtalskyj E. Root amputation and hemisection. Indication, technique and restoration. J Can Dent Assoc 1986; 52(4):307–8.
6. M. Najeeb Saad, Jorge Moreno, Cameron Crawford. Hemisection as an Alternative Treatment for Decayed Multirooted Terminal Abutment: A Case Report. JADC june 2009, Vol. 75, No 5, 387-390
7.  Kost WJ, Stakiw JE. Root amputation and hemisection J. Canad Dent Assoc1991; 57: 42-5
8.  Biesterfeld RC and Taintar JF : Endodontic considerations related to hemisection and root amputation. N W Dent 1978;157:142-148.
9.  Kurtzman GM, Silverstein LH, Shatz PC. Hemisection as an alternative treatment for vertically fractured mandibular molars. Compend Contin Educ Dent 2006; 27(2):126–9.