-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 
print

Adhesion Bridges

Adhesion Bridges can be used anteriorly or posteriorly. The original idea was popularized by Dr Ray Bertolotti. Ray credited the concept to a Dr.Yamashita, a Japanese clinician. The approach came of age with the development of a very long-lived opaque luting agent, Kuraray's Panavia, still available today although reformulated into several quite-different materials for a wider array of applications. Choosing the right Panavia is critical to success. Dr Walford has taken this extracoronal retentive design and re-created it as an intracoronal, inlay/flange design, greatly enhancing its success, esthetics , and breadth of applicability.




Previously - the Maryland Bridge


The Maryland design depended on extracoronal retentive grooves mated to a thin metal flange, and was basically flawed. It has needed improvement for years. Fragile retention, facial show of metal, greying of abutments, and indeterminate seating, all derive from the use of extracoronal grooves mated to a lingual metal flange.

New Design for the Anterior - the Walford Inlay Flange Bridge/Splint


Dr Walford has developed a better alternative using inlay retention, (i.e.,intracoronal rather than extracoronal retention), still coupled to a metal flange. Outwardly it still looks like a Maryland Bridge, except, because the proximals are not thinned by placement of retentive proximal grooves, there is no greying of the interproximals.

Three fa,ilies of placement Indications

This design can be used as a
1.Single abutment retainer cantilever pontic anterior tooth replacement
2.Double-abutment as a single tooth replacement
2.Multiple abutment longer spans for splinting and/or replacing missing teeth.

Small spans are outlined at Inlay Adhesive Bridges.An example is detailed below.

Finished case replacing 12 lateral incisor cantilevered from 13 lingual retainer



Impression after tooth preparation



Retainer and pontic


Model with relief in pontic area to allow sub-tissue pontic emergence



Surgical site day of placement, mini-flap and osseus relief



Appearance day of placement after luting



Five Year Appearance




Extremely esthetic tooth replacements can be achieved with this method when using a porcelain pontic. This adds an alternative for anterior tooth replacement to the restorative quiver, at a fee of one third of an implant. It may often provide the most effective treatment for missing teeth in small edentulous spaces where bone volume and root proximity make implants problematic, yet esthetic demands are high.

Long Anterior spans

Larger spans and a full technique guide to their placement can be found at The Inlay Flange Bridge

Example: A Long span case, splinting with subsequent chairside pontic fabrication

Below are images detailing a long-span periodontal splint where mobile teeth with an unfavorable crown/root ratio in a lower anterior sextant are splinted. A pontic,fabricated chairside with composite resin, replaces a missing tooth.






Summary- A win-win in MID (Minimally Invasive Dentistry)

These are significant advantages to the patient and the practitioner both. If one could be assured, as I am, that there will be no likelihood of retainers loosening,are these not kinder, more intelligent, and more conservative ways to solve old clinical problems?

At this point I have complete confidence in the Walford Inlay-Flange? adhesive design. It is not to be used in every case, of course not. But if the key design criteria are met, case selection is correct,and cementation is meticulous, it is top-flight dental care. It stands head and shoulders above conventional treatment in its benefits to patient and operator alike.There is negligible endodontic stress on the abutment tooth, facial tooth structure is not removed, occlusal reductions need not penetrate into dentin but remain bonded with the best adhesive system we have in dentistry long-term, which is enamel bonding. Think of it as Porcelain Laminate Veneer adhesion without any potential for chipping. 20 year plus lifespan? Of course.

One Patient's Testimonial- Cantilever Anterior bridge replacing 22, porcelain sub-tissue pontic.


"The tooth is looking really good. Everyone that I show can't believe that it isn't real.
The whole thing has been an interesting experience, and I thank you for what you have done for me. You and Arlene have been awesome. The procedure was entirely painless, including the initial tooth removal that we had to start off with." Patient JG, male age 40.


Posterior Adhesive design






The Adhesion Bridge or 'Resin-Bonded Fixed Partial Denture' is under-utilized by general dentists today.This is unfortunate, because the modality offers outstanding conservatism and tremendous restorative power. Like all indirect procedures, the trick is to develop the preparation and proceed through all the steps with precision.

The importance of the luting agent


It should be understood that the success of the adhesion bridge depends on high performance bonding. These designs will not work with classic mineral cements developing 4 to 8 MPa.of bonding strength. But they will succeed and deliver long life with resin cements achieving 25 MPa or more.

The schematic and photo above convey a basic posterior design.

History of the Posterior Adhesive Bridge


Dr. Chris Wyatt, Chair, Prosthodontics,UBC School of Dentistry, has published an excellent historical review of the evolution of this design,in the JCDA December 2007, January 2008. It is thoroughly referenced and offers statistical backbone to the assertion that this prosthetic approach is now reliable.
See http://www.cda-adc.ca/jcda/vol-73/issue-10/933.htmlexternal link

As I have been placing a wide variety of adhesion devices over 30 years, I have personally followed the professional journey traced by Dr. Wyatt's article.


Posterior designs

The posterior schematic above is effective. Sometimes called the Yamashita design from the doctor who initiated and popularized it,the salient features are:
  1. Preparation is enamel-bonded , unless dentin is exposed as a consequence of removing a previous underlying restoration
  2. Finish lines are supragingival
  3. Height of retainers is seldom more than half the height of the clinical crown
  4. Parallel grooves embrace the tooth by 180 degrees or more, providing reciprocal retention along short walls which are closely tapered. The goal is for the restoration to be mechanically retentive and resistant to dislodgement before any cement is used; The restoration has to stand on its own two feet in classic terms, depending on a very powerful and resilient adhesive interface to keep these features approximated.
  5. As much surface area is covered as possible;
  6. As close to 100% of the enamel of the abutment is retained, providing maximally stable adhesive bond.The occlusal reduction is shallow accomplished with a diamond burs.
  7. The retainers are engineered for stiffness, specifying alloy of sufficient stiffness when retainers must be thin.

One might call the retainer design a short 3/4 crown.But this fails to describe how different it can be from conventional outline form, nor how creative and versatile it can be.



In the photo above, note that the mesial contact is not broken. The facial and mesiobuccal surfaces remain untreated, to improve cosmetics.

In this 65 year old male patient,it makes excellent sense to exclude the mesial surface from the retainer preparation. In a whole lifetime he has not managed to decay the mesial surface, so it seems sensible to expect that no extension for prevention is really needed. The 180 degree embrace in this case was achieved with a light disto-buccal hollow-ground concavity, as per Dr.Richard Tucker, rather than a groove.

Another feature of this particular case is that it was prepared without anesthesia, as the enamel was not perforated during preparation. We were able to establish the margins with a spiral-cut chamfer carbide,dry, giving crystal clear marginal definition, because, unlike dentin, there is no need for coolant on enamel if a light touch and sharp bur are employed.

No retraction cord was required, further simplifying the procedure, and increasing post-operative comfort. Being supragingival, there are no possible long-term periodontal impacts. No temporary crowns were fabricated, reducing cost, time and complexity, and eliminating the possible loss of the temporary as a clinical contingency.

A smaller amount of gold was cast, compared to conventional preparations, lowering the fee to the patient by reducing lab costs. Less than half the chair time was required relative to a conventional bridge, further reducing the fee for the patient.

Cementation was without anesthesia, improving comfort, reducing chair time,and improving proprioception of the occlusion for an accurate and comfortable placement appointment.

Consequently there was less likelihood of time lost to post-placement occlusal adjustment.

Because it is exclusively in enamel,the probability of long-term pulpal damage, or postoperative sensitivity is nil. There is absolutely no endodontic downside.


The Benefit of anterior and Posterior Adhesion Bridges - A win-win in MID (Minimally Invasive Dentistry)


The above are significant advantages to the patient and practitioner alike. If one could be assured, as I am, that there will be no likelihood of retainers loosening, are these not kinder, more intelligent, and more conservative ways to solve old clinical problems?

At this point I have complete confidence in adhesive design. It is not to be used in every case, of course not. But if the key design criteria are met, case selection is correct,and cementation is meticulous, it is top-flight dental care. It stands head and shoulders above conventional treatment in its benefits to patient and operator alike, and in its kindly, less-invasive qualities.