ALL-ON-4 IMPLANTS

Introduction

If your dentist has suggested the All-on-4 dental implant treatment protocol to you, this is all you need to know about this procedure. So let us start at the beginning. Pioneered by Dr. Palo Maloin 1998, this technique is also fondly called the Malo All-on-4 technique after him. What he figured out was an effective method to rehabilitate edentulous, i.e., patients lacking teeth (where e stands for out, dent for tooth + lous) and soon to be edentulous patients using a minimum number of implants with immediate loading.

So before we move on, we would like to acquaint you with a few more dental terminologies that we will frequently encounter in the course of this discussion. Do scroll back up to revise the meaning of these frequently used dental terms.


GLOSSARY OF FREQUENTLY USED DENTAL TERMINOLOGIES:

DENTAL TERM MEANING
Maxilla The jaw or jawbone, specifically the upper jaw in most vertebrates. In humans it also forms part of the nose and eye socket.
Mandible The jaw or jawbone, specifically in the lower part of the face in most mammals is called the mandible.
Dental Implant The dental implant is a surgical component, shaped like the root of a natural tooth, that is placed within the bone of the maxilla or mandible to support an artificial tooth like restoration.
Abutment The dental implant abutment is that part of the fixture that connects the artificial crown to the underlying dental implant.
Multi unit abutment Again, the connection between the dental implant and the crown. However these are different from the conventional ones as they are angulated and helps in achieving the proper direction for restoration of tilted implants
Osseointegration The process of the bone intimately adapting to the surface of the dental implant, securing it to the bone is called osseointegration. This procedure may take anywhere between 3-6 months for completion.
Cantilever Technically, a cantilever means that a long beam is supported only on one end and is free on the other end.
Anterior Front or up ahead
Posterior Behind
Prosthesis An artificial replacement of a missing natural body part, which in our case is the tooth.
Provisional Restoration The artificial restoration that is placed temporarily till healing completes or the final restoration is ready is called the provisional or temporary restoration.
Occlusion Defined simply, occlusion is the science of contact of the surfaces of teeth in different situations, eg while biting, while chewing, while talking, swallowing, etc.
Bone resorption The physiological, sometimes pathological process of decrease in the height, width and volume of bone due to various factors like age, disease, medication etc.
Immediate Loading The process of placement of a prosthesis immediately after the implant surgery to assist in esthetics, function, rehabilitation and recovery.
Denture Conversion The process of using a premade denture for immediate loading after the completion of surgery.

2. Rationale

Now that we are slightly better acquainted with a few technical term, let us move on to the rationale of All -on-4 implants.

The philosophy of all on 4 implants is the use of 4 implants, 2 angulated straight in the anterior portion of the maxilla, or the front portion of the upper jaw, and 2 tilted in the posterior portion of the maxilla, which can be tilted up till 45º . So what this does is, helps in engaging bone in the posterior region of the maxilla where bone resorption is seen very frequently and there is insufficient amount of bone for the placement of straight implants without any additional procedures.

The All on 4 full mouth rehabilitation helps us navigate difficult cases of insufficient bone without additional complicated surgical procedures like bone grafting, bone augmentation, sinus lift procedures; all of which have variable surgical success.

Additionally, the tilted implants, helps us prevent a cantilever or overhang which can be deleterious in the long term success of the dental implant and the prosthesis. The tilting of the implants decreases the length of the overhang, giving rise to better prognosis or future of the implant.

This method advocates tilting distal implants in edentulous arches which enables us in the placement of longer implants, improved prosthetic support with shorter cantilever arm, improved inter implant distance and improved anchorage in the bone.

1. Increases bone to implant contact,providing support even in reduced bone volume.
2. In the anterior implants, slight tilt helps in bicortical anchorage, which is engagement in two bony parts.
3. Avoids vital structure like nerves and the maxillary sinus, thus making implant placement possible without additional procedures.
4. Even load distribution with placement of upto 12, or in some cases even 14 teeth.
5. Immediate loading of implants after surgery.
6. Lesser number of implants for a full mouth rehabilitation

3. ADVANTAGE OF THE ALL-ON-4 FULL MOUTH REHABILITATION


LONG TERM DOCUMENTED SUCCESS :

The All on 4 treatment protocol has now been around for 2 decades and there are innumerable studies done by dental stalwarts that demonstrate the high success rate of this procedure.

Long term studies which have spanned over 10 years has proven the following survival rates for edentulous maxilla and mandible:

3-4 YEARS: 96.3% TO 100%

5-10 YEARS: 94.8% TO 98.0%

This one study by Francetti et al in 2012 titled Bone level changes around axial and tilted implants in Full arch fixed Immediate Restorations, demonstrates the good bone response around tilted implants.




SHORTER TREATMENT TIME:

THE time to teeth is considerably shortened because the tissues do not have to recover from complicated surgical procedures. This makes immediate function possible with good occlusion, restoring not just esthetics but also function.


LOWER COSTS:

The use of just 4 implants without any additional grafting procedures significantly reduces the price of full mouth rehabilitation, making it affordable to many. Thus retirees and pensioners can consider the All on 4 treatment to improve their quality of life.


INCREASED PATIENT SATISFACTION:

Since there is a rapid improvement in the quality of life, with regards to function, esthetics, speech and confidence most patients would recommend this procedure to others. In a study done by Babbush in 2012 titled Post treatment quantification of patient experiences with full arch implant treatment using a modification of a OHIP- 14 Questionnaire, 95% of the patients termed themselves as extremely satisfied while 98% would definitely recommend it to their colleagues and relatives.


GENERAL CONSIDERATIONS FOR THE CLINICIAN:


4. STEPS IN THE PROCEDURE:

The phases in the procedure can be simply explained with the following flow chart:

A prosthodontically driven approach for the All on 4 treatment protocol ensures the best results. The initial surgical phase is undertaken after thorough evaluation of the patient’s clinical and medical condition. The surgical phase entails the following:


SURGICAL PHASE:
1. The preparation of an osseous shelf to level the alveolar ridge and establish optimum implant sites and the provision of adequate interocclusal space.
2. Planning and placement of implants using the All on 4 surgical guide, with the posterior implant not tilted more than 45 degrees.
3. Verification of implant positions with a radiograph or volumetric image
4. Flap closure

The surgical procedure can also be carried out with the use of 3D printed guided stents which assist in precise placement of implants according to the plan. In such a case it will be a graftless procedure.

The prosthetic phase begins soon after surgery when a previously made denture is converted intra-orally.


PROSTHETIC PHASE (INTERMEDIATE AND FINAL)
1. Open tray impression with splinted impression copings
2. Jig verification of the implant positions
3. Jaw relation verification
4. Bridge design using CAD-CAM technology
5. Fabrication of all zirconia bridge or titanium framework for crown cementation
6. Trial and finishing
7. Final luting of crowns to Titanium framework (Malo bridge) and final fixation in the mouth.

Conclusion:

The ALL ON 4 Implant methodology provides a viable solution for resorbed ridges and has proven to give good long term results. The cost effectiveness, immediate function, reduced postoperative morbidity should be taken into account while planning this treatment.



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