INTRODUCTION:
Two stage surgical protocol was given by Branemark, but it has several pre-requisites(1)-
1. Countersinking the implant below crestal bone.
2. Obtaining and maintaining the soft tissue covering over the implant for 3-6 month.
3. Maintaining a non-loaded implant environment for 3-6 months.

The Reason For Countersinking The Implant
Below Crestal Bone Arei.
i. To reduce and minimize the bacterial infection.
ii. To prevent the apical migration of oral epithelium along the body of implant.
iii. To reduce and minimize the risk of early implant loading during bone remodelling.

DISADVANTAGES OF 2-STAGE PROTOCOL
A second stage surgery is necessary to uncover these implants and place a prosthetic abutment.

ADVANTAGES
A high degree of long term, clinical rigid fixation has been reported after 2-stage surgery. But during the last 15-years several authors have reported that root form implants may Osseointegrate even though they reside above the bone
and through the soft tissues during early bone remodelling. This surgical approach has been called as one-stage or non-submerged implant procedures and this eliminates the second-stage implant uncovery surgery.
 

HISTORICAL BACKGROUND OF IMMEDIATE LOADING
- Since long, dentists were experimenting with numerous designs and materials for early implant prototypes.
- In 1963 Lincow introduced root form implants for immediate occlusal load which were named as vent -plants.
- In 1970’s Ledermann used titanium plasma sprayed implants and immediately loaded them with mandibular overdenture.
- In 1970’s Schroeder(1976,1978,1981) showed that the submerged technique was not a prerequisite for success of implants.
- However, success came for immediate loading in 1980’s(Schroeder and Babbush)(2).
 

THEN CAME THE BIG QUESTION: WHY THE NEED FOR IMMEDIATE LOADING?
The answer to this was associated with lot of studies which were being carried out and was concluded that first and formost reason was Psychological then was Esthetics then Functional and last but not the least was Economics
involved.(1,3,14,16)

Indications
- Single tooth replacement.
- Partial edentulism.
- Full edentulism.
Contraindications
- Bruxism
- Smoking.
- Reduced bone quality & quantity.
- Short length implants.
ADVANTAGES:
- This eliminates the second –stage implant uncovery surgery.
- As a result the tissue discomfort and healing associated with second-stage surgery are eliminated.
- The dentist also eliminates the surgical time for uncovery and suture removal.
- In addition the soft tissue is already mature before fabrication of final Prosthesis.
- Immediate loading of implants loads the implant with a provisional restoration at the same appointment or shortly thereafter.
DISADVANTAGES:
- High chances of failure. More bone loss compared to delayed loading. Peri-implantitis due to loading.
- Post operative complications.
- Patient cooperation mandatory

Precise and strict following of protocol for implant surgery may take care of above mentioned disadvantages.

PROTOCOL FOR COMPLETELY EDENTULOUS PATIENTS (8,11,13) 2 DIFFERENT APPROACHES ARE THERE
First approach- involves placing several more implants than the usual treatment plan for a conventional healing period and out of them only selected implants in an arch (around 3 or more) are only immediately loaded with a transitional
prosthesis. Other implants are left submerged for delayed loading.This approach was given by Schnitman et al in 1990.This approach can be used only in edentulous mandible where abundent bone is present.Tarnow et al (1997)-also followed this approach.He did a study in 10 consecutive completely edentulous cases over 5-years,Out of them 6 were mandibular arches and 4 were maxillary arches, 10-13 implants were used in each arch for final prosthesis, 66 out of 69 implants integrated. Failure rate was 4% and success rate was 96%.

Second approach-This includes immediate occlusal loading of all the implants inserted. Theimplants are splinted together which decreases the  stresses on all the developing interfaces and increases the stability, retention and strength of the transitional prosthesis during the initial healing

GUIDELINES FOR IMMEDIATE LOADING(6,7,8,11)
1. The bone should be of good quality.
2. The implant should engage strong cortical bone with initial stability.
3. The type of implant should be screw type with rough surface.
4. Cantilever should be avoided.
5. An occlusal scheme that promotes axial loading rather than horizontal stress must be designed.
6. Night guards in patient’s with parafunctional habits.

FACTORS MODIFYING IMMEDIATE IMPLANT LOADING
- Surgical factors included- primary implant surgery and surgical technique being used.
- Host related factors included-quantity and quality of bone; type of wound healing
- Implant related factors included-implant design, surface coating and length of implant
- Occlusion related factors included-quantity and quality of force;prosthetic design.

Finally the need for re-evaluation of BRANEMARK PROTOCOL was done and concluded that loading per se does not impede the healing process to occur thus Prematurely loaded implants are capable of integration.

APPROACHES TO REDUCE LOADING PERIOD
Careful patient selection, Non-functional loading of the implants, to identify an effective way to reduce micro-motion beneath the critical threshold of deleterious micro-motion.
A NEW PROTOCOL FOR IMMEDIATE FUNCTIONAL LOADING
Fabrication of a provisional restoration prior to surgery, Immediately after the last implant is placed convert a previously constructed provisional prosthesis into an immediate implant supported non-removable prosthesis, Impressions for the final restoration is made. Opportunity to evaluate the esthetics/phonetics and functional loading during the normal osseointegration healing period. This prosthesis appears to have a splinting effect, locking the implants in place as
bone heals around them.

STUDIES ON IMMEDIATE LOADED IMPLANTS WITH FIXED PROSTHESIS(3,17,18)

Author       Patients       Implants        Success Rate
Ericsson    16                 88                          100%
Chow          27                 123                        98.3%
Collaert      25                  114                        98%
Testori       15                   103                        98.4%

Anterior zone of mandible provided success rates of >90% but lower success rates were observed for short implants placed in unfavourable bone morphology and distal positions. Most studies (Jaffin and Berman,Misch and Degidi) suggested that a high number of implants(8-12) are required in maxilla.

OUTCOMES OF IMMEDIATE LOADING PROTOCOLS
Primary stability of the implant was the underlying requisite for predictable results. The role of implant length on implant success was limited. Short to medium term studies suggest that treatment with fixed prosthesis in the anterior mandible is predictable irrespective of implant type, surface topography and prosthesis design. Atleast 4 implants should be placed in the edentulous anterior mandible to support a fixed prosthesis. To achieve results in extraction sites, implant placement should be restricted to sites without a history of periodontal involvement.

Finally, the marginal bone loss measured, irrespective of prosthesis design, was of the same magnitude as presented for the conventional loading approach.
 

SUMMARY
Immediate implant loading achieved similar success rates as those reported in the delayed 2- stage approach. Primary implant stability is a key factor to consider before attempting immediate implant loading.

Surgery-, Host-, Implant-, and Occlusion related factors may influence the outcomes of immediate implant loading. Studies are needed to understand the possibility of immediate implant loading in patients who are diabetics,
osteoporotics and smokers as well as those who have other systemic compromising diseases. Long term, prospective studies particularly in Indians are still needed to evaluate other potential determining factors on this technique.
 

CONCLUSION
The level of predictability and high success of current implant therapy has provided reasons to reassess the guidelines.
With the trend of shortening treatment time and reducing patient discomfort, immediate loading implants has emerged as an alternate approach. However, meticulous selection is needed to integrate this treatment into daily practice.
Regular maintainence is the key factor to ensure long term success of immediately loaded implants.

REFERENCES
1) Akagwa Y., Ichikawa Y. et al. Interface histology of unloaded and easily loaded partially stabilized zirconia endosseous
implant in Initial bone healing. J. Prosthet. Dent. 1993; 69:599- 604.
2) Babush C. Dental implants- Principles and Practice” W.B. Saunder’s Company.
3) Ericsson I. Et al. Early functional loading using Branemark Dental Implants. Int. J. Periodontics Restorative Dent. 2002;
22:9-19.
4) Guichet D.L., Yoshinobu D. et al. Effect of splinting and interperoximal tightness on load transfer by implant restorations. J. Prosthet Dent. 2002; 87:528-35.
5) Hobo S. et al. Osseointegration and occlusal rehabilitation. Quintessence Publishing Company, 1989.
6) Holt R., Vernino A. et al. Effect of early exposure on the integration of dental implants : Part 2 – Clinical findings at 6
months post loading. Int. J. Periodontics Restorative Dent. 2001; 21:407-414.
7) Hurzeler M.B., Zuhr O. et al. Distraction osteogenesis : A  treatment tool to improve baseline conditions for esthetic
restorations on immediately placed dental implants – A case report. Int. J. Periodontics Restorative Dent. 2002; 22:451-
461.
8) Kammeyer G., Proussaefs P. et al. Conversion of a complete denture to a provisional implant-supported screw-retained fixed prosthesis for immediate-loading of a completely edentulous
arch. J. Prosthet. Dent. 2002; 87:473-6.
9) Lange G.D., Tadjoedin E. et al. Fate of a the H.A. coating of loaded implants in the Augmented sinus floor : A human case study of retrieved implants. Int. J. Periodontics Dent. 2002; 22: 287-296.
10) Lazzara R.J., Portar S.P. et al. Prospective multicenter study evaluating loading of osseotite implants two months after placement one year results. Journal of Esthetic Dentistry, 1998; 10 : 280-289.
11) McKinney R.V., Lemons J.E. The Dental Implant. American Academy of Implant Prosthodontics.
12) Misch C.E. Contemporary implant dentistry. Mosby Publishing Company.
13) Reddy S.M., Geuris W.C. et al. Mandibular growth following implant restoration : Does Wolff’s law apply to residual ridge resorption? Int. J. Periodontics Restorative Dent. 2002; 22:315- 321.
14) Rung Charassaeng K., Lozada L.J. et al. Peri-implant tissue response of immediately loaded, threaded, H.A. coated
implants : 1 year results. J. Prosthet. Dent. 2002; 87:173-81.

15) Smet E.D., Steenbenke D.V. et al. The influence of plaque and /or excessive loading on marginal soft and hard tissue
reaction around Branemark implants. A review of literature and experience. Int. J. Periodontics Restorative Dent. 2001;
21:381-393.
16) Srinivasan B., Chitnis D.P., Meshrum S.M. et al. To load immediately or not to load that is the question. JIPS; June
2003; 3(2):31-38.
17) Testori T. et al. Healing of osseotite implants under submerged and immediate loading condition in a single patient : A case report and interface analysis after 2 months. Int. J. Periodontics Restorative Dent. 2002; 22:345-353.
18) Testori T. et al. Immediate loading of osseotite implants: A case report and histologic analysis after 4 months of occlusal loading. Int. J. Periodontics Restorative Dent. 2001; 21:451-459.
19) Trisi P., Rebaudi A. et al. Progressive bone adaptation of titanium implants during and after orthodontic load in humans. Int. J. Periodontics Restorative Dent. 2002; 22:31-43.
20) www.google.com
21) www.mosby.com