Adhesive preservation of fractured teeth

By Dr. Nobuo Masaka

If the fragments haven’t dislocated, you can often preserve the tooth by simply bonding a post or core with C&B-Metabond®. The adhesive will lock the fragments to the reinforcing post, preventing movement and creating a unified structure that can support a traditional restoration.

In 1982 (18 years ago!) we treated our first four vertical root fractures using C&B-Metabond. We carefully explained to the patients that this approach was very speculative. But since the alternative was extraction, they agreed to the treatment. The results were far better that expected. In fact, all four roots are still functioning today.

By 1985 we had sufficient data to consider this approach a proven technique, and were using it routinely at the Masaka Dental Clinic. As you can see in Table A, during our first twelve years experience with the technique only 10% of the 48 fractured teeth required later extraction.



Figures A-D: Until recently, teeth suffering complex root fracture were beyond repair. Though broken into three fragments, this tooth was saved using a new technique involving extraction, adhesive repair and replantation. (A & B: pretreatment condition. C: Fragments after extraction. D: Post-operative radiograph.)



In this article we’ll discuss adhesive treatment of more complicated fractures ... where the root has broken into several pieces ... or the fragments have dislocated ... or the break extends all the way to the apex, preventing intraoral application of the adhesive resin.

At first we thought these complex fractures defied restoration, particularly if the fracture was old and had gone undiagnosed.

However the prognosis improved tremendously in 1989, when Dr. Katsunari Nishihara of the Department of Oral Surgery of Tokyo University Medical School developed a procedure for extracting the tooth, repairing it with adhesive extraorally, and then replanting it.

Though drastic, this approach is surprisingly successful provided:

1. the entire operation can be performed quickly. The longer the tooth is out of the socket, the worse the prognosis.
2. there has been relatively little damage to the periodontal membrane.
3. the adhesive is applied properly.
4. there is no infection.
5. the replanted tooth can be adequately
immobilized during healing, and ...
6. the period of immobilization is adequate ... but not excessive.

After extraction, the periodontal membrane must be kept moist with physiologic saline and antibiotic solution. Extreme care should be taken to avoid damaging the membrane. But most important, the dentist must work rapidly to minimize the time the membrane is out of the socket.

To prevent infection the patient is given antibiotics two days prior to the operation. The socket is irrigated with physiologic saline/antibiotic during the operation. And after the operation, the patient is given antibiotics effective against anaerobes.

The length of post-operative stabilization is also important. If it is too short, the tooth will not heal properly. But if it is too long, the tooth will ankylose. Splinting is generally removed and the tooth allowed to function naturally after eight to ten weeks ... even though the tooth is still slightly mobile.

Table B shows six years experience tracking 22 adhesive replantations. Some of the early cases required subsequent periodontal treatment, but as we have improved our technique, the results have improved. All replantations performed during the past three years have been complication-free.



Figure E: If the fracture site of a conical root has developed a lesion, the prognosis seems to
improve if the root is rotated so the denuded portion of the root opposes healthy bone, and healthy
periodontal membrane opposes the lesion.


We are constantly refining both tools and technique.

For example, we’ve developed an instrument that holds the segments tightly during cementing, yet reduces damage to the all-important tissue tags.

When a dislocation has remained undiagnosed, a lesion often forms adjacent to the fracture, destroying the apposing periodontium and alveolus. Tissue damage like this, of course, can compromise replantation.

However, we recently discovered that we can improve the prognosis when restoring a conical root by rotating the tooth slightly when we replant it. After cementing the fragments, we carefully curette the root surface where the membrane has been destroyed. By turning he tooth before inserting it into the socket, the denuded portion of the root faces healthy bone, and remaining tissue tags face the alveolar defect. The result is generally a soft tissue attachment at the bone defect, ankylosis at the
periodontal defect ... and attached gingiva coronal to both.

The following three cases illustrate the basic extraction/repair technique ...

CASE 1: RESTORING THE SEVERELY FRACTURED VITAL TOOTH

Figure 1: #7 showed a complete mesiodistal fracture with dislocation of the fragments. Treating a fracture like this intraorally is difficult because the tooth not only requires adhesive repair, but also endodontic therapy.

Figure 2: Complicating the treatment further, the root was long, and the fracture extended all the way to the apex. It would have been very difficult to deliver the adhesive the full length of the root.

Figure 3: Therefore the tooth was extracted for extraoral repair. Notice that the fracture extended to the apices of the mesial roots.

Figure 4: The fractured surfaces were cleaned, taking care to minimize damage to periodontal membrane. Then they were cemented together using C&B-Metabond.

Figure 5: While out of the socket, the tooth was kept moist with physiologic saline/antibiotic solution. After endodontic therapy, adhesive repair and core construction, the tooth was replanted in the socket.

Figure 6: After replanting, the core was splinted to the adjacent teeth using wire and C&B-Metabond.

After 6 weeks the splint was removed and the tooth restored with a full crown. Though 6 weeks is a typical resting period for this type of replanting operation, in this particular case extreme immobility after healing suggests there may be partial ankylosis.

Figure 7: The radiograph after crown cementation. By coating a gutta-percha point with C&B-Metabond before insertion, we deliver adhesive to the apex. This provides a biologic seal at the same time it strengthens the repaired root. (A small piece of amalgam can been seen outside the root. This particle was expressed during the surgical procedure and was replanted with the tooth.)

Note: Our current technique for restoring this type of fracture delays core construction until after the tooth is replanted and healed. This shortens the surgery and reduces the time the root is out of the socket.

Also, over the years we have gradually shortened the period of immobilization in order to minimize ankylosis. If the alveolar process is sound without significant resorption, the splint may be removed after as little as 2 weeks.


CASE 2: REPAIRING THE SEVERELY FRACTURED POST-RESTORED TOOTH

Figure 8: The patient presented for recementation of a 10-year-old Richmond crown. Examination revealed an old root fracture. The fragments had dislocated and granulation tissue had grown into the fissure.

Figure 9: The tooth was carefully extracted to minimize trauma to the periodontal membrane. The fracture surfaces were cleaned with a scaler, and treated with C&B-Metabond’s green 10-3 solution for 10 seconds.

Figure 10: The post of the old crown was tin-plated to improve the adhesive bond. C&B-Metabond was applied to the tooth fragments and cemented directly to the post.

Figure 11: The radiograph at the 14-month recall, reveals some resorption and ankylosis; however, the tooth remains stabile and asymptomatic. Replantation ad-hesive therapy is clearly drastic action, but it is a viable treatment ... particularly in cases like this, where extraction is the only alternative.

 

 




CASE 3: REPAIRING THE FRACTURED TOOTH ACCOMPANIED BY SEVERE BONE LOSS

Figure 12: Left untreated, a root fracture had caused extensive periodontal damage. The distal fragment had completely separated.

Figure 13: The bridge could not be saved, so it was removed, and the components of #13 extracted. The fractured surfaces were cleaned and the tooth cemented together using C&B-Metabond.

The adhesive both restored the tooth’s structural integrity and sealed it to block penetration of bacteria and toxins.

Figure 14: Because it lacked a clinical crown, the replanted tooth healed passively under a cross-suture without splinting. Thirty-four days after the operation, the root was exposed and prepared for a post and core.

Figure 15: In the new bridge #4 and #5 were double-abutted to provide a stronger foundation for the bridge and eliminate the possibility of recurring fracture.

Figure 16: 4-month post-operative radiograph. More time will be required for osseous regeneration. (Incidentally, the image at apex of #5 is the adhesive resin sealing he canal.)

 


About the author ...
Dr. Nobuo Masaka is one of Japan’s most respected dentists. Founder of the Masaka Dental Clinic, he is also a lecturer at Tokyo Dental College and Vice President of the Japan Society of Adhesive Dentistry.

Dr. Masaka is arguably the world’s most-experienced 4-META user, having cemented his first case with the adhesive back in 1980 ... 20 years ago.

Under his guidance, the Masaka Dental Clinic has pioneered a number of adhesive techniques that are just beginning to make their way into mainstream dentistry.

For example, he was largely responsible for developing:
1.) the bonded endodontic post (1980)
2.) the adhesive treatment for fractured roots (1982)
3.) the adhesive amalgam restoration (1987)
4.) the adhesive pulp cap (1989)
5.) the surgical extraction, adhesive repair and replantation of fractured roots (1990)

So we were honored when Dr. Masaka agreed to expand on a series of adhesive articles he authored for the “Nippon Dental Review.”