Treatment Plan for Implants in Function Zone

Vinay PavanKumar KPost graduate student

AECS Maaruti Dental College

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“ CSR of dental implants is generally high and that implant location plays an important role in implant success.CSR of implants in the mandible seems to be slightly higher than in maxilla—about a 4% difference. The success rate of implants in the anterior regions seems to be higher than in the posterior regions of the jaws, mostly due to the quality of bone: about 12% difference between anterior maxilla and posterior maxilla, and about 4% difference between anterior mandible and posterior mandible”

Tolstunov L. Implant zones of the jaws: implant location and related success rate. J Oral Implantol. 2007;33(4):211-20

Treatment Planning

“If you are not planning for success, then you are planning for failure”

treatment plan \tret-mant pla˘n\: The sequence of procedures planned for the treatment of a patient after diagnosis – GPT 8

Functional implant zones (FIZ)

Functional implant zones (FIZ) are the alveolar jaw regions where dental implants can be inserted with or without supplemental surgical procedures for the purpose of functional prosthetic rehabilitation of the stomatognathic system

Functional implant zones (FIZ)

• Zone 1 (FIZ-1): traumatic zone zone of the alveolar ridge of premaxilla

• Zone 2 (FIZ-2) : sinus zone, bilateral zone of the alveolar ridge of

posterior maxilla located at the base of maxillary sinus from the second premolar to pterygoid plates

Functional implant zones (FIZ)

• Zone 3 (FIZ-3) : interforaminal zone, a zone of the alveolar ridge of anterior

mandible (symphyseal area)

• Zone 4 (FIZ-4): ischemic zone, a bilateral zone of the alveolar ridge of

posterior mandible from the second premolar to the retromolar pad.

FIZ 1 : Traumatic zone

• It including eight anterior teeth: 4 incisors, 2 canines and 2 first premolars

• The anterior maxilla has protruding alveolar process with thin labial and thick palatal cortical plates covering and protecting upper front teeth

• This prominent positioning is is responsible for bone and soft-tissue injuries of the facial skeleton during fall, RTA and domestic trauma

• Post extraction bone resorption is 3 dimensional, with the greatest loss of bone in the bucco-palatal (the width)

• Mainly on the buccal side of the alveolar ridge

• 50% bone loss occur during the 12 months following tooth extraction.

• 2/3rd of the horizontal bone loss occurs within 3 months and 1/3rd takes place within the remaining 9 months of the first year post extraction

• The loss of bone height is smaller, reported to be about 1 mm within the first 6 months post extraction

• The data of healing and remodeling of the alveolar crest after the tooth loss are especially important in the premaxillary area due to esthetic considerations.

• Implant rehabilitation in FIZ 1 often entails staged hard and soft tissue procedures to rebuild collapsed tissue and achieve the original and natural esthetics, function, and phonetics

Atleast consider 10 dynamics should be considered during implant treatment in the anterior maxilla :

1. A detailed history of facial trauma or a tooth loss

2. A comprehensive clinical and radiographic examination including conventional (PA, occlusal, panoramic x-rays) and tomographic imaging.

3. Early bone augmentation procedures and bone grafting techniques to improve and reconstruct missing or deficient alveolar ridge and create an adequate foundation for an endosseous implant

4. Consider soft tissue grafting to increase or create a layer of attached gingiva, treat all patients as having a high smile line

5. Consider slightly more palatal implant placement to engage the remaining palatal cortex with its strength needed for primary implant stability without compromising esthetics and function

6. Use an anatomically tapered implant design with a good adaptation to the surrounding socket

7. Consider two-stage surgery and avoid immediate load

8. If immediate provisionalization is utilized, take the prosthesis out of occlusion, use protective occlusal schemes; consider prosthetic remodeling techniques for an improvement of implant emergence profile

9. Wait sufficient amount of time before fully loading of an implant with a history of alveolar crest grafting (at least 6 months)

10. Instruct patient to avoid heavy biting for at least one year after delivery of the final prosthesis, avoid any front facial trauma or contact sport, and maintain meticulous oral hygiene

FIZ 2 : Sinus Zone FIZ 2 : bilateral maxillary posterior zone that extends from the second premolar to the pterygoid plates is located at the base of maxillary sinuses compromised bone quality (types 3 and 4) ; increase an implant failure rate

sinus pneumatization after a loss of posterior tooth/teeth necessitates sinus lift procedure with vertical bone augmentation

Guidelines for posterior teeth

• The predictability of the outcome of an implant restoration in the posterior part of the mouth is dependent on :

1. Available space2. Implant number and position3. Occlusal considerations4. Type of prosthesis5. Overall treatment plan

Available space

• Available ossesous space:

-7.5 mm of bone height is required for a 6 mm fixture

- 8.5 mm is required for a 7 mm fixture

• at least 2 mm of bone between the apical end of the implant

and neurovascular structures

• The implant should be at least 1.5 mm : the adjacent teeth

• The implant should be at least 3 mm : an adjacent implant

• A wider diameter implant should be selected for molar teeth

• molar implant restorations : 2.5 mm away from the adjacent tooth to allow development of appropriate restorative contours

• 6 mm of bone (buccolingually) : 4 mm diameter implant

• Available restorative space :- 10 mm of space : the residual ridge & the opposing occlusion - 7 mm would be considered the bare minimum

• Minimal enameloplasy or minimal restorative therapy may be considered to create space

Implant number and position

• The number of implants is dependent on bone quantity and quality

• Maxilla : 1 implant for each tooth

• Cantilever type prostheses have been associated with higher rates of failure

• The clinician has to decide if a bone augmentation procedure is justified or whether a more simple approach of cantilevering would suffice

• With three implants; offset the implants and position

them for a tripod effect

• Use of a wider diameter implant provides an equivalent

benefit to the non linear configuration

• When insufficient osseous volume exists in the posterior

maxilla and the patient does not want to undergo a sinus

augmentation procedure, consideration giving implant

placement in the tuberosity area

Occlusal considerations

• Implant protected occlussion :The centric contacts are adjusted with light occlusal contact on the implants; the rationale being the opposing natural dentition is often compressed on firm closure

• Cuspal inclinations on implant supported restorations should also be shallower

• Anterior disclusion is easier when posterior occlusal anatomy is shallow

Type of restoration

• Cemented v/s Screw retained

• Splinted v/s Non splinted

• Abutment level v/s implant level restoration

Overall Rx Plan

• Decisions to use implants should be based on prosthetically oriented risk assessment

• Prosthetically oriented risk assessment involving comprehensive evaluation of potential abutment teeth

• the decision should be based on risk assessment and cost effectiveness of the procedures

FIZ 3 : INTERFORAMINAL ZONE

This zone of mandibular alveolar ridge is located between mental foramen on each side or from the first premolar tooth on one side to the first premolar tooth on the other side

• It has thin and narrow alveolar ridge often requires an especially careful and skilled surgical implant insertion

• A successful placement of 2 to 6 in edentulous arch cases offer a stable foundation for a variety of implant-retained and implant-supported removable and fixed mandibular prostheses

FIZ 4: ISCHEMIC ZONE

The alveolar process of posterior mandible is located behind the mental foramen on each side and extends from the second premolar to the retromolar pad

• Vascularization to the alveolar ridge and teeth diminishes with loss of teeth, in elderly patients with alveolar crest resorbtion other chronic conditions results in “Relative ischemia”. Thus it called has Ischemic Zone

• Decrease of blood supply to the bone and soft tissue can compromise bone growth, repair, and maintenance and increase failures of bone grafting and implant integration, amplifying rate of early implant failures

• A heavy masticatory demand during function, especially for people with parafunctional habits

• Two to three implants : replacement of missing second premolar, first molar occasionally second molar

Posterior mandibular implants should be placed such that the exit angle of the screw access should point towards the inner incline of the palatal cusp

Placement of two implants in molar positions can compensate for poor bone quality by double the anchorage surface area

Double implants closely mimic the anatomy• eliminates antero-posterior cantilever, • reduction of rotational forces exerted• reduction of screw loosening

Dental implant success–failure analysis based on implant location

Other considerations

• The use platform switched helps in the preservation of the crestal bone

• Osteoconductive roughened implant surface topography (acid-etched, RBM) significantly improve an implant success rate in any zone of the jaws by enhancing primary mechanical implant stability and BIC

• Better Implant stabilty : immediate loading, reducing healing time, maintaining a crestal bone level and facilitating an implant hygiene

Reference

• Misch CE. Contemporary implant dentistry. Elsevier Health Sciences; 3rd edition 2014

• Tolstunov L. Implant zones of the jaws: implant location and related success rate. J Oral Implantol. 2007;33(4):211-20

• Jivraj S, Chee W. Treatment planning of implants in posterior quadrants. British dental journal. 2006 Jul 8;201(1):13-23.

• Dolanmaz D, Senel FC, Pektas ZÖ. Dental Implants in Posterior Maxilla: Diagnostic and Treatment Aspects. International journal of dentistry. 2012;2012.