FROM THE DESK OF ALAN M. MELTZER DMD MScD

The behavior of bone around and between adjacent implants:

When an implant is exposed to the oral environment, there is classically bone loss to the first thread associated with the formation of biologic width. This genetically ordained formation of biologic width has two components which are described as horizontal and vertical. Each component measures about 1.5 millimeters.

If adjacent implants are greater than 3 millimeters apart, the horizontal components of biologic width fail to overlap and a bridge of bone will remain between them. This bridge of bone will support the soft tissue.

If adjacent implants are less than 3 millimeters apart, then, as biologic width forms, the horizontal components of biologic width overlap and destroy the interproximal bridge of bone, eliminating the required soft tissue support producing a significant black triangle.

Preserve the inter-implant bone and support the soft tissue.
Remember only 3.5 millimeters of soft tissue covers the inter-implant bony crest

A method of reducing the impact of the formation of biologic width through the use of platform switching will be explored in my next monograph.

Photos courtesy of Dr. R. Coucchetto-Italy

FROM THE DESK OF ALAN M. MELTZER DMD MScD

In this issue I will explore the formation of papilla between adjacent implants. As you may recall from my previous monograph, when a single tooth implant is placed the formation of the papilla is controlled by the distance from the crest of bone on the adjacent natural teeth to the crown contact points. The general rule is as long as the distance from the tooth contact point to the crest of bone on the adjacent teeth is 5 millimeters or less there is an excellent chance the papilla will form. Simply stated, the fate of the papilla is controlled by the attachment level of the tissue to the natural tooth and not by the situation associated with the implant side of the interproximal space.

In the case of adjacent implants, there is no tooth-associated supracrestal fiber system to support the inter-implant papilla. Additionally, in this case the position of the contact point is completely within the control of the restorative dentist and laboratory since these adjacent implants are restored by crowns. Therefore, the measure used is simply the thickness of tissue covering the interproximal bone. The average tissue thickness is 3.5 millimeters. It is for this reason that adjacent implants frequently produce black triangles rather than full papilla.

This aesthetic dilemma remains one of the great challenges of implant dentistry. When one replaces two central incisors, symmetry can be maintained as long as the inter-implant distance is greater than 3 millimeters (see my next monograph for further explanation). The true problem surfaces when one needs to replace either a central incisor and its adjacent lateral incisor or a canine and adjacent lateral incisor. When the implant side is compared with the opposite tooth side, there will be an obvious difference in soft tissue morphology creating an aesthetic compromise. One can expect only 3.5 millimeters of soft tissue over the bone between implants, while 5-6 millimeters or more can be expected between natural teeth. This requires the restorative dentist to alter tooth form or create a black triangle.

Note the lack of symmetry of the central lateral papilla (#7 and #8 are adjacent implant crowns compared to natural teeth #9 and #10)

What is the best solution? Place one implant and cantilever off the lateral incisor. This solution works because the edentulous lateral incisor site can be augmented at the time of implant replacement. Connective tissue augmentation of the pontic site can produce almost 7 millimeters of soft tissue thickness compared to 3.4 millimeters between implants. The use of a properly placed wide-diameter implant in either the canine or central incisor site is suggested. A lateral incisor can be cantilevered off either the canine or central incisor as required. An implant with an internal connection is suggested to insure abutment stability.

FROM THE DESK OF ALAN M. MELTZER DMD MScD

In this monograph, I will explore the fate of the mid-facial free gingival margin around single tooth implants. As stated at the conclusion of the last monograph, papillae either stay the same over time or improve, while the mid-facial worsens over time.

How much worse does the mid-facial become over time? It is a well-documented fact that over a 12 to 24 month period the mid-facial will recede approximately 1 millimeter. The degree of recession is generally more pronounced in a thin periodontium than in a thick one.

Why does this happen? A tooth has the ability to form a periodontal supracrestal fiber attachment while implants do not. This variation in the formation of biologic width from supracrestal around teeth to crestal-subcrestal around implants is responsible for the aesthetic compromise.

How can this problem be overcome? The solution requires over-correction of the mid-facial either prior to tooth extraction, at the time of tooth extraction, or at the time of implant placement. Available techniques may include orthodontic extrusion prior to extraction, soft tissue augmentation, hard tissue augmentation or some combination of the above. It is because of this mid-facial aesthetic issue that immediate placements are generally contraindicated in thin periodontal biotypes with high smile lines and high aesthetic demands. This special requirement is not an implant integration problem, but rather an aesthetic issue. Correcting this deficiency after the implant and restoration have been placed is extremely difficult and in some cases impossible.

Does grafting the socket at the time of tooth extraction solve this problem? No. While socket grafting is necessary in the aesthetic zone at the time of tooth extraction, it must be combined with other clinical approaches to maximize the aesthetic outcome. Remember that socket preservation is not the answer to this mid-facial problem; overcorrection is required.

FROM THE DESK OF ALAN M. MELTZER DMD MScD

In this third monograph, I will explore the subject of the interdental papilla with focus on the single tooth implant.

How close can a dental implant be placed to a natural tooth root? It is well documented that an implant should be placed no closer than 1 millimeter from a natural tooth root (green arrow) or the implant will compromise the bone support on the adjacent natural tooth. The generally accepted distance is approximately 1.5millimeters.

What is the minimal width of an interdental space required for implant placement? The average width of most standard sized dental implants is about 4 millimeters. Therefore, the minimal width is 7 millimeters.This allows 4 millimeters for the implant and 1 millimeters mesially and distally for root clearance.

What about the use of narrow diameter implants? Most dental manufacturers produce narrow diameter implants. Most have a prosthetic platform in the 3.4 millimeter range (3.25 mm implant with a 3.4 mm prosthetic seating surface). This would reduce the interdental minimal width requirement to 6 millimeters. There are some narrower implants (3 millimeter range) but the potential risk of metal fatigue and implant fracture must always be taken into consideration. These specialized narrow implants should only be used in areas of minimal occlusal stress such as upper lateral incisors or lower incisors.

How can the loss of papillary tissue be predicted? Once again, it is a well-documented fact that this aesthetic dilemma can be evaluated preoperatively.

The key measurement involves evaluating the periodontal health of the adjacent natural teeth. If one measures the distance from the contact point to the crest of bone on the adjacent teeth (red arrow) this will accurately give you the ability to predict the chances of maintaining or regenerating the papilla.

If the distance from the contact point to the crest of bone on the teeth adjacent to the proposed implant site is 4 to 5 millimeters, you have an almost 100% chance of regaining the papilla. If the distance is 6 millimeters you have about a 50% chance of getting the papilla back. If the distance measures 7 millimeters the odds fall to roughly 25%.

Note: Papillae either stay the same over time or improve. The mid-facial either stays the same over time or worsens. The mid-facial dilemma will be the subject of my next monograph.

FROM THE DESK OF ALAN M. MELTZER DMD MScD

In this monograph, I will explore the role of immediate implant placement in the dental implant armamentarium.

Definition of immediate implant placement: The placement of an implant in an extraction socket at the time of extraction or explantation.

Can this be done with success? YES, it is a well-documented fact that implants can be placed at the time of extraction with extremely high success (survival) rates. The complete answer is that immediately placed implants survive well, but there are numerous aesthetic issues which can be created using this approach. The current state of the art dictates that immediate placements should not be the treatment of choice in aesthetically demanding cases.

Does the placement of an implant at the time of extraction preserve bone? NO, the placement of an implant in a socket at the time of extraction has nothing to do with bone preservation.

What are some of the contraindications to immediate placement? Infected sockets or pockets, poor primary implant stability, aesthetically demanding cases. Patients who present with an allergy to penicillin seem to have a higher complication rate with immediate placement.

If the socket is intact, how wide a gap can be left between the socket wall and the implant wall? If the residual defect between the socket wall and the implant surface exceeds 2 millimeters, then that portion of the implant will not integrate unless it is filled with a bone graft and protected by a regenerative membrane.

What if the bony walls of the socket are fully or partially absent? Immediate placement can still produce high survival rates as long as infection is controlled, a bone graft and/or regenerative membrane is used, and good primary stability is achieved.Additionally, it is prudent only to use this approach in patients with low aesthetic demand or areas where aesthetics are not a major consideration.

Why is immediate placement a poor choice in aesthetically demanding areas? When a tooth is extracted, the bone remodels regardless of whether an implant is placed immediately or not. The thin buccal plate, even if intact, undergoes palatal and apical resorption. This moves the free soft tissue margin apically and palatally leaving a tooth which appears longer than its neighbors. The facial collapse produces an unaesthetic emergence. It is well documented that this mid-facial tissue will recede approximately 1 millimeter over a 12-24 month period. While papillary areas have the potential to stay the same over time or improve, the mid-facial rarely stays the same and usually worsens (recedes) over time. This issue occurs with all implant systems.

The solution to this complex dilemma will be the subject of my next monographs.

FROM THE DESK OF ALAN M. MELTZER DMD MScD

Over the past several years there have been numerous advances in dental implant technology. In the next several months it is my plan to update you on these advances. I will also explore the advantages and disadvantages of these new technologies and aid you in positioning them properly in your upcoming treatment plans. It is extremely important that marketing hype be separated from evidence-based fact. No approach has become obsolete; they each occupy an important place in proper dental implant treatment. The objective of this first monograph will be directed toward defining terms.

IMPLANT PLACEMENT TERMINOLOGY

Classic placement: The placement of an implant in an intact edentulous site that has not been disturbed by a graft or extraction for at least six months.

Immediate placement: The placement of an implant in a socket at the time of tooth extraction or the immediate placement of a new implant in a site of an implant explantation.

Early delayed placement: The placement of an implant in an extraction socket 8 weeks post-extraction.

Late delayed placement: The placement of an implant in an extraction socket 4-6 months after an extraction.

IMPLANT HEALING TERMINOLOGY

Single-stage surgery or transmucosal healing: An implant heals exposed to the oral environment. This can be achieved using a transgingival implant design or using a two-piece implant with a healing abutment.

Two-stage surgery or submucosal healing: The traditional approach where an implant is completely submerged below the soft tissue during its integration phase.

IMPLANT LOADING TERMINOLOGY

Immediate loading: A poorly defined term which has fallen out of favor and has been replaced by two more appropriate terms.

Immediate occlusal loading: The loading of an implant within 72 hours of placement. More specifically a restoration is placed on an implant and the restoration is in occlusal contact with the opposing dentition.

Immediate non-occlusal (functional) loading: An implant is restored within 72 hours of placement, but the restoration is out of occlusal contact in centric and lateral excursions.

Regular loading: The loading of an implant after a classic integration period which is usually defined as 3 months in the mandible and 6 months in the maxilla.

Early loading: The loading of an implant after 6-8 weeks of integration.