INTRODUCTION

Tooth extraction whether traumatic or atraumatic, results in alveolar bone loss both in height and width. An average of 40-60% of original height and width is expected to be lost after extraction, most of which takes place within the first year. The rate of reduction of residual alveolar ridges is greater in mandibular (0.4mm/year) than in maxillary arches (0.1mm/year), 1mm in vertical bone 2-2.5 mm in horizontal bone resorption corresponding to 2mm soft tissue recession.
 This might negatively influence bone volume that is needed for future implant placement and also the ideal esthetic restoration and functional outcomes. Socket preservation allows preserving alveolar bone height, potentially regenerating new bone and thus maintaining the soft tissue height.

RATIONALE

According to Bays 1986, the rationale lies on the basis that the alveolar ridge resorption is an unavoidable sequelae to tooth loss. The most recent attempt to overcome the detrimental effects of deficient alveolar ridge is socket preservation, which maintains adequate dimensions of bone for implant placement as well as maintains a more esthetic gingival profile.

Lekovic et al 1997 compared outcome of ridge augmentation with or without absorbable barrier membranes. In the membrane group

• Less crestal bone loss (-0.38mm versus -1.50mm)
• More internal socket fill (-5.81mm versus -3.94mm)
• Less horizontal ridge resorption (-1.31mm versus -4.56mm)

Iasella et al 2003 – study comprised of subjects receiving either extraction alone or tetracycline hydrated freeze dried bone allograft (FDBA) and a collagen membrane.

• Greater bone formation in augmented sites after 6 months healing period.
• Maintained bone width,height and position of bone.
• Average 1.3mm ridge height gain, whereas 1mm crestal loss in control group.

Iasella et al.2003, Becker et al.1996, Pinholt et al.1992, Pinholt et al.1990 – various bone grafting materials and techniques are being used.

• steogenic bone graft materials supagely viable osteoblasts that form new bone.
  
• steoinductive grafts stimulate pluripotential mesenchymalcells to differentiate into osteoblasts that form new bone.
  
• Osteoconductive graft material merely act as a lattice for cell growth.

These grafts aid in osseoconduction by preserving space and excluding unwanted cells from the wound but also to promote new bone.
Schallhorn 1968- autologous grafts are considered ideal having osteogenic, osteoinductive and osseoconductive properties.
In addition they do not possess the risk of disease transmission, donor and recipient being the same individual (Goldberg and Stevenson 1987)
They do increase the risk of additional pain, infection and donor site morbidity. (Feinberg and Fonseca 1986)
Maatz et al 1952, 1953,1954- transplantation of living cells increases the possibility of retained cell viability and graft revascularization.
Brugnami et al.1999, Kassolis et al.2000, Simon et al.1998- bone graft materials are used to augment bony defects adjacent to dental implants and to repair chronic extraction socket defects, with or without use of barrier membranes.
Graft materials are believed to prevent collapse of membranes.( Nenins anf Mellonig 1992, Wang et al.2005)
Collagen membranes are preferred because of there absorbable property thereby eliminating need for another surgery to retrieve it and also because of being highly biocompatible with surrounding oral tissues. (Wang et al.2004, Sableman 1985, Postlewaite et al. 1978)

CLINICAL GOALS AND BIOLOGIC CONSIDERATIONS FOR SOCKET PRESERVATION
The primary goal is to preserve both the hard and soft tissue volume and architecture, to optimize function and esthetics.
To maintain an osteoconductive environment and isolate the area from deleterious effects of oral debris during healing.
To maximize the supagely of osteoprogenitor cells and their ability to invade the osteocondutive zone.

SOCKET PRESERVATION PROCEDURE

EXODONTIA

After recording a careful medical history and no contraindications to any surgical process is evaluated, local anesthesia is administered. Radiographic analysis of the surgical site for the root anatomy gives an ideal pathway for exodontias.

Sulcular incisions –performed with 15C scalpel to rupture the supracrestal attachment apagearatus.

Periotomes – to luxate the periodontal ligament space. These are used to completely rupture the gingival fibres at the cervical area of the tooth. The instrument is kept converging apageroximately at an angle of  20 degrees from the long axis of tooth, this ensures the periotome within the crest of alveolar bone only.
Then it is inserted into the periodontal ligament and moved in mesio-disal direction thereby widening the PDL uptil the two-third of root length.
When sufficient tooth mobility is achieved dental forceps are apagelied.

Curettage-  socket is thoroughly curetted of all soft tissue debris/
Bleeding from the socket is stimulated, his forms the key to maximum bone fill, since blood contains fundamental proteins and growth factors for bone healing. Extra blood is taken out by scrapageing the socket wall with curettes or rotary instruments, this triggers Regional Acceleratory Phenomena ( RAP) which stimulates new bone formation and graft incorporation.

Inspection- socket is carefully inspected and decision is made based on following factors:-
Integrity and thickness of buccal plate
Presence of periapical pathologies
Number and morphology of roots 

TECHNIQUE

Traditional socket preservation with or without collagen wound dressing material :-

Indicated when the buccal plate is > / = 1mm thickness.
Bone wall thickness is measured using Boley gauge calliper at apageroximately 2-3mm below the alveolar crest.
According to Korsens2002, Spray et al.2000, bone plate >1mm have significantly more favourable healing capacity, is less prone to future resorption.
An absorbable collagen dressing material may be used to promote clot stabilization. Collagen is an hemostatic agent and possesses the ability to stimulate platelet aggregation and enhanced fibrin linkage which leads to clot formation, stability and maturation (Sableman 1985).
Also collagen is chemotactic for fibroblasts in vitro this enhances cell migration and promotes primary soverage necessary for bone growth (Postlethwaite et al. 1978)
Cross- mattress sutures are then placed for 14 days of initial healing phase

Figure 1: RVG of fractured endodontically treated mandibular right second premolar	Figure 2: Intact socket wall after atraumatic extraction
Figure 3:Alloplast used	Figure 4: NOVA Bone Putty being placed in the socket
Figure 5 Clinical view of graft in place	Figure 6 Collaplug (Zimmer) used to seal the socket
Figure 7: Cytoplast sutures in place	Figure 8 : Post Op IOPA after four months showing mature bone

POST SURGICAL INSRTUCTIONS:-

1. To minimize the amount of graft particles that become dislodged and help promote an excellent graft result:

• Do not disturb or touch the wound.
• Do not apagely pressure with your tongue or fingers to the grafted area, as the material is movable during the initial healing.
• Do not smoke for at least two weeks after surgery.
• Do not drink alcoholic beverages during the first week after surgery.
• Avoid chewing or creating pressure on the graft site

2. Gentle rinsing should be started on the evening of surgery or the first post-operative day.
Use a warm salt water rinse (1/2 a teaspoon of salt in a glass of warm water) at least 4 to 5 times a day.
3.  0.12% Chlorhexidine gluconate oral rinse for next two weeks.
Gentle tooth brushing with a soft bristle tooth brush and tooth paste and flossing should be started on the evening of surgery or the first post-operative day and continued at least twice a day. Not to disturb the graft area. 
4. systemic anti-biotics prescribed if signs of active infection are found.
500mg amoxicillin three times/day for 10 days in case the patient is allergic to penicillin, azithromycin 500mg for three days.
Painkillers such as ibuprofen to relieve discomfort associated with the procedure.
Healing process monitored radiograohically.

REFERENCES:-

• Ashman,A. 1995 Ridge Preservation The New Buzzword In Dentistry. Implant Soc, 6, page1-7
• Ashman,A. 2000 Post Extraction Ridge Preservation Using A Synthetic Alloplast. Implant Dent ,9,page.168-176
• Barboza,E.P. 1999 Localised Ridge Maintenance Using Bone Membrane. Implant Dent ,8 (2),page.167-172
• Bartee,B.K..1995 A Simplified Technique For Ridge Preservation After Tooth Extraction. Dent Today,14,page 62-67
• Iasella,J.M., H.Greenwell,R.L. Miller, M.Hill,C. Drisko,A.A.Bohra,et al. 2003 Ridge preservation with freeze- dried bone allograft and a collagen membrane compared to extraction socket alone for implant site development- a clinical and histologic study in humans. Journal of Periodontol,74,page 990-999.
• Nevins,M. , J.T. Mellonig 1994. The advantages of localized ridge augmentation prior to implant placement: a staged event. International Journal Periodontics Restorative Dentistry, 14,page.96-111