The Restorative Cycle in Dentistry

Clinical Relevance:

The replacement of failed restorative dentistry continues to be a major part of operative dental procedures performed in the US and Canada.*{1,2,6,7} In addition, dental continuing education tends to concentrate on technical procedures with little emphasis on the long term outcomes for restorative choices. The choice of restorative materials combined with the operator’s skill level has a profound influence on the life expectancy of a restoration. How long a restoration will last has direct consequences on oral health.

 

Summary:

This paper will discuss the importance of selecting restorative materials that are most survivable within the environment into which they are placed. The clinical relevance for the use of direct gold, especially in younger patients or in virgin caries will be presented.In addition, the article is intended to present the advantages for oral health of placing restorative materials with the highest probability of long-term success in various environments.

Introduction:

Restorative dentistry is an invasive and irreversible procedure that has a finite life. Therefore, possibly the most significant consequence for the repair of dental defects and indeed for all operative interventions is the need to replace restorations when they fail.*{1,2,3,4} The unintended consequence for all operative procedures is to place the patient’s tooth and/or the tooth site into a “restorative cycle” that will continue throughout the life of the patient. The fundamental concept of a restorative cycle {RC} brings into focus the loss of tissue around existing restorations on a recurring basis.

The restorative cycle consist of three major events; first the loss of tooth structure due to trauma or the initial disease process. Next is, the loss of tooth structure due to the necessary process of preparing a tooth to receive a restoration. The final event occurs when the restoration fails and must be replaced. With the replacement restoration the restorative cycle is repeated. All restorative options are subject to restorative cycles. Add to this the human tendency to settle into routines, where the average dentist gives little thought, other than color, to the material chosen and even less thought to the “environment” into which that material is to be placed and the restorative cycle is accelerated.

There are a number of factors that determine the length of the restorative cycle for any given restorative material. These include the environment into which the restorative material is to be placed. For example, the age and health of the patient, diet, the occlusal loads brought by the patient, oral hygiene, plaque levels and the type and levels of bacteria within the oral environment of the patient. Physical properties of the restorative material and the skill level of the operator, at the time of placement, also contribute to the how long a restoration will last until it ultimately fails.

This fundamental understanding of the finite life for all restorative procedures as they relate to the environment the patient presents should be one of the determining factors for which restorative material will be best to use in any particular restorative situation. Therefore any attempt to quantify the predicted life of a restoration should help dentists and patients make informed decisions about restorative options.

Review of the literature*{2, 6} and through personal observations from 30+ years of restorative practice, it is the understanding of the author that posterior composite restorations, in general, have a life expectancy of 6-10 years. Therefore the restorative cycle assigned to posterior composites would be 6-10. Similarly a RC of 12-18 would be assigned to alloy restorations. Cast gold would have a RC of 30-40 and gold foil/direct gold would have a RC of 45-55. In addition, this refers to first generation restorations. Second generation restorations, on average, would have restorative cycles shorter than first generation restorations due to an increase in the size of the restoration and greater loss of tooth structure leading to a weaker tooth less able to stand up to stresses within the mouth. In addition, changes in the “environment”, ageing of the patient , changes in eating habits, systemic disease processes, un-noticed iatrogenic flaws, to name a few, will have direct influences on the life of restorations.

Clinical Cases:

The restorative cycle and its effects clinically can be better understood by the following cases. The first case {Fig 1-10} is virgin caries in a patient in his mid fifties. The patient is in good health and demonstrates good home care with a low caries rate. The patient will need the restoration to possibly last 45+ years, thus a restorative material with a RC of 6-10 or even 12-18 will be insufficient. Restorations with longer restorative cycles will better serve the needs of the patient.

Because this is a first time restoration where the occlusal load will not be directed on the restoration and cosmetic concerns are low either a gold casting or direct gold would work well. Direct gold/gold foil was chosen to allow for a conservative preparation without having to flair the prep in order to place an indirect casting. In addition, due to the depth of caries a base of Fuji IX was placed.

 

Fig 1 fig 1

Fig 2fig2

Fig 3fig3

Fig 4fig4

Fig 5fig5

Fig 6fig6

Fig 7fig7

Fig 8fig8

Fig 9fig9

Fig 10fig10

The use of EZ gold, developed by Lloyd Baum from Loma Linda, allows for placement of a direct gold restoration of this size in a reasonable amount of time within a busy restorative practice. Another advantage of direct gold is that the restoration can be placed in one appointment without a lab fee. The prep design can be kept conservative without having to extend the proximal cavo-surface margins to accommodate for casting placement and finishing. Finally the restoration has a very good chance of lasting 50 years in the environment in which it is placed.

The next case {Fig 11-14} is interesting on several levels. First due to the age of the patient, the decision for what restorative material to use will have a profound influence on the future health of the tooth and tooth site. Another issue concerns who is doing what and when. The environment is as follows; the patient is 10 years old with caries into the dentin of the mesial pit of his 6 year molar. The patient has good oral hygiene with a low caries rate. The patient is a bright energetic young man with a good understanding of oral health and has the ability to undergo a procedure the will take approximately 45 minutes under a rubber dam. The author wishes to interject here that this is a situation that should be addressed further by everyone. Even though it might sound counter intuitive, in the author’s opinion, pediatric dentists should be doing direct gold restorations. It has been a personal observation that when patients leave the pediatric dental practice and come into a general restorative practice, a lot of the 6 and 12 year molars have composite restorations. A significant number of these restorations are failing with others not long behind. The problem with this situation is this; a real opportunity to treat the patient with optimal care has been lost. Therefore, in the opinion of the author direct foil should be taught in pediatric residencies. If the receiving restorative dentist acquires the patient with a direct gold restoration in the posterior teeth, there is a good chance that future replacement restorative work would be more manageable for long term health of the patient and retention of the tooth.

This case is a good example of this. Because this 10 year old has a restoration with a RC of 50+ placed, there is a good chance that the molar will remain intact, without need for full coverage and/or root canal therapy, for the remainder of the patient’s life. Another point that should be made at this point is this. Predictions for future success and/or failure for restorative materials can only be made on current conditions and past known history of the environment. Assuming conditions will remain the same, good hygiene and health, predictability of restorative materials should remain consistent.

Fig 11fig11

Fig 12fig12

Fig 13fig13

Fig 14fig14

The next case {Fig 15-20} is that of virgin caries on a patient in their late thirties. Again, the environment is that of a younger patient with good oral hygiene and low caries rate with a good understanding of excellence in dentistry and a desire for health and longevity. In this case, pit and fissure caries was deep into the dentin thus a foundation of Fuji IX was placed after simple caries removal had been completed. The final prep was completed to ideal depth using the Fuji IX as the floor of the prep. EZ gold was used to complete a class one gold foil restoration that should give the patient years of service beyond other materials. Also notice in the final photo the posterior composite on the first molar that will need replacing shortly. Again an opportunity lost but at least salvageable with a gold casting.

Fig 15fig15 Fig 16fig16

Fig 17fig17 Fig 18fig18

Fig 19fig19 Fig 20fig20

 

The final case {Fig 21-22} presents with the following environment. The patient is in their middle thirties with moderate to poor oral hygiene. The patient is a tobacco user, smoking at least a pack of cigarettes a day. His diet consist of high carbohydrate and high sugar intake including several sodas a day. He is interested in the least expensive treatment possible and really does not place oral health or dental care as a high priority. This patient is in the author’s opinion “below the line” for optimal dental care. However, the patient should be treated with respect and restorative choices should be selected that bring cost and reasonable longevity into play. This patient can be converted to an “above the line” patient who values oral health and long term dental restorative care. He simply needs to be educated and shown the value of good dental care in a respectful and caring dental environment.

In a case where there is poor oral hygiene with moderate to high dental carries, a restorative material should be selected that can stand up to the environment into which it is placed. Something needs to be done, just waiting for the patient to realize the error in their thinking or putting in the latest material just because everyone else is using it is inappropriate. In this environment posterior composites would be a poor choice. Studies show there is significantly less recurrent caries around amalgam then resin composites.*{5, personal observation} Therefore, alloy is best to consider in an environment such as this. Corrosion will seal the restorations allowing for longer life in a marginal environment. In addition, the cost will be less than other materials allowing, in many cases, a patient with limited means and/or poor priority selection, to save their teeth. The author prefers a high copper alloy such as Tytin by Kerr.

The restorations should be polished. This will not only create a surface that is easier to clean, it is less likely to have food and plaque stick. By polishing alloy restorations or properly finishing all restorative materials, the dentist is establishing a trust relationship with the patient. In addition, longer life of the restoration is more likely. Also, by polishing and finishing all restorative treatment the dentist is giving the patient the opportunity to see and feel the difference between restorative works that is not finished. It has been the experience of the author that this will help influence the patient to understand the value of good oral health and quality restorative work. Through this experience the patient will be more likely to place high quality restorative work on a higher priority than it might have been. The operator will find that cost is not the problem with accepting quality restorative work, it is all about priorities and trust.

When patients are educated about physical properties of materials and given the opportunity to experience quality restorative work, health and longevity become more important than cosmetics. Cosmetics is still important it is simply placed in a more realistic position with relation to wants verses needs.

Fig 21fig21

Fig 22fig 22

Finally, if dentists would do routine outcome assessments for restorative work they complete, documenting the time of placement and time before replacement is needed, accurate restorative cycles could be assigned to all restorative procedures within a given practice. Restorative cycles could be classified by material, restoration size and configuration, generation of placement and patient risk factors.

It is the opinion of the author that having accurate information about how long various restorative options last before replacement is necessary will give the dentist, that completed the procedure, a better understanding about the long term effects of the various restorative choices within his/her practice. In addition, in the opinion of the author, it is the responsibility of all restorative dentists to be competent in the placement of all available restorative materials. There is no one restorative material or technique that is appropriate for all situations.

1. Moore, D.L. and Stewart, J.L. Prevalence of defective dental restorations, J. Pros Dentistry, April 1967 p373-378.

2. Fontana, M. and Gonzalez-Cabezas, C. Secondary Caries and Restoration Replacement: An Unresolved Problem, Compendium, January 2000, p15-24.

3. Henry, D.B. A Philosophy for Restoring Virgin Caries, J. Operative Dentistry, Sep/Oct 2008-Vol 33 #5 p475-483.

4. Henry, D.B. The Consequences of Restorative Cycles J. Operative Dentistry, Nov 2009, Vol 34, issue 6, p759-760.

5. Hilton, T.J., Broome, J, Fundamentals of Operative Dentistry, Third Edition, Chapter 10 p295.

 

6. Roulet J.F., Review of the clinical survival of direct and indirect restorations in posterior teeth of permanent dentition, J. Dent, 1997, Nov, 25{6} p459-473.

7. Manhart J., Chen H., Hamm G., Hickel R., Benefits and disadvantages of tooth-colored alternatives to amalgam, J. Operative Dentistry, 2004, Sept/Oct, Vol 29, {5} p481-508.

 

Dan B. Henry DDS, FACD, FICD

fig23