Oral Health Group

Restoring Damaged Tooth Structure with a Novel Resilient Bioactive Restorative Material

April 5, 2017
by John C. Comisi, DDS, MAGD

“Accidents will happen”. 1 They appear in our offices most every day. When they do present, our job is to help remedy the situation with the best mechanisms at our disposal. How do you approach these cases in your office? How are you going to restore these situations, and what type of material will you use?

Properly placed direct restorations can be your patient’s best solution, especially when you want to preserve healthy tooth structure and not reduce the tooth to a smaller weaker aspect of itself.
“Injection molding” of teeth can be a major asset to your armamentarium to overcome this dilemma. You can maintain a substantial amount of tooth structure and also strengthen the integrity of the tooth.

Additionally, what type of materials will you use to perform this restoration? I would propose that if you were also to use a bioactive/bio-mineralizing restorative material in this process, you can also improve its ability to heal from the damage it has sustained.

Bioactive materials have recently been defined as those “that form a surface layer of an apatite-like material in the presence of [saliva or a saliva substitute].” 2

These types of materials are important since these materials are active in response to the dynamic environment of the oral cavity we have previously described. The typical acid attack that occurs with almost everything we eat and drink causes a demineralization process to occur intraorally. Most current dental filling materials are essentially passive and do nothing to protect the teeth they are theoretically there to protect. They certainly fill the void created by the damage of the decay process, but they do not encumber further damage that can occur via secondary decay from the acidic environment that precipitated the damage in the first place. With the average life span of these typical composite restorative materials being 5.7 years 3, perhaps it is time to reconsider the current conventional mechanism of resin-based bonding.

Bioactive materials are an important for consideration because they can 1) reduce post-op sensitivity, 2) reduce marginal leakage and secondary caries and 3) probably more importantly, the use of bioactive materials can be significantly less technique sensitive. Moisture is ubiquitous in the oral cavity, and all of our typical composite restorative materials require “drying” of the tooth prior to restoring. However, it has been shown that all the moisture in the dentin tubules can never be eliminated. The enamel of the tooth is a “semi-permeable membrane” with a constant flow of fluids outwards from the pulp 4. As we know, the odontoblasts are dentin-secreting cells that survive the whole life of a healthy tooth and are critically involved in transmission of sensory stimuli from the dentin-pulp complex and in the cellular defense against pathogens. 5

Matrix Metalloproteinases (MMPs) are enzymes found in dentin and secreted by odontoblasts. 5 Their role is to protect the tooth against the advancing acid attack of dental decay. However, since we use acids in our bonding procedures, these same MMPs become activated and attack and degrade the hybrid layer formed by traditional bonding agents in the restorative process. Many articles over the years have reiterated this fact. Pashley, Tay et al, state “if all exposed collagen fibrils were enveloped by resin then MMPs would not have free access to water, an obligatory requirement for these enzymes” to activate 6. However in our hybridization process of dentin bonding, there is no realistic way to make this occur. Water is always present in the tooth and actually necessary to enable effective resin bonding to occur. And so the enzymatic breakdown is inevitable.

Endogenous enzymes remain entrapped within the hybrid layer during resin the infiltration process, and our acidic bonding agents themselves (irrespective of whether they are etch and rinse or self-etch) activate these endogenous protease enzymes. And since impregnation of resin into dentin is frequently incomplete, these exposed and denuded dentin collagen matrices become exposed to free water, are enzymatically disrupted and ultimately contribute to degradation of the hybrid layer and resin restoration failure. 7

So what can we do? In my practice we have adopted the use of Activa Bioactive Restorative and Activa Base/Liner (Pulpdent). The unique hydrophillic resin matrix of the materials integrates with the tooth structure and enables the release of calcium, phosphates and fluoride which are favorable ions, while at the same time maintaining its physical properties and structure. Activa is biocompatible, dynamic in the oral cavity and are very aesthetic and wear resistant. These materials have been shown via the calcium and phosphates release, to stimulate the creation of apatite at the tooth-restoration interface, and they are resilient and not brittle due to the rubberized urethane component, which allows for even distribution of forces throughout the restoration 8.

Let’s look at a case that presented recently in which we chose to restore damaged structure with bioactive materials and “injection molding”. A 23-year-old female presented with fractured tooth #10 (Fig. 1). The trauma was caused while she was swimming and hit a rock. Clinical and radiographic imaging indicated close, but no direct pulpal involvement (Fig. 2). When evaluating the occlusion (Figs. 3 & 4), it was obvious that there was need for orthodontic correction of the occlusion. However, there was an immediate need to provide an aesthetic solution at that appointment. Treatment options certainly included a full coverage indirect restoration, but that would have removed a significant amount of tooth structure, which very likely would weaken and compromise the integrity of the remaining portion of the tooth structure. It was decided that there was a need to protect the exposed dentin, since there was no pulpal exposure, and injection mold a direct restoration using a bio-active restorative material.

Fig. 1

Fig. 2

Fig. 3

Fig. 4

First, an indirect pulp cap was accomplished using Activa™ Bioactive Base-Liner material. This material, as all materials in the Activa line of bioactive products, will release calcium and phosphate ions to form apatite and help with healing the tooth structure. The resin matrix of the material enables it to penetrate into the dentin, seals it and protects the underlying structure from microleakage and premature failure. Additionally, as previously stated, the material provides a shock-absorbing ability to distribute forces so that it responds similarly to dentin. After placing an Isolite® Systems Isolation device, the Activa™ Bioactive Base-Liner was applied to the exposed dentin, allowed to be in contact with the dentin for twenty seconds and then light cured for twenty seconds (Fig. 5).

Next we proceeded to restore the broken tooth structure. In this case, we wanted to work with material that would be resilient and able to distribute forces throughout the restoration so that we could reduce structural failure. Additionally, we needed a material that could provide a wonderful esthetic result. Again, we called upon the Active™ Bioactive Restorative material. After we prepared the tooth for “injection molding” by removal of the biofilm with use of aluminum-trihydroxide abrasive powder (BioClear System) in an air abrasion unit and making appropriate room on the mesial, distal and lingual for the new material (Fig. 6), we placed BioClear System matrices and adapted them to create an “aquarium” around the tooth for the “injection molding” process (Fig. 7). The process of injection molding involves the liquefaction via heating of traditional composite materials to allow for a smooth and harmonious total enveloping of the material into the matrix aquarium. Since Activa is already very flowable, it is a perfect material to use in the injection molding process without the need to be heated. The matrices were then trimmed back in the incisal areas to make room for the cannula of the bioactive restorative material (Fig. 8) and then 37% phosphoric acid was injected into the matrix aquarium (Fig. 9) and then washed out after 20 seconds and dried, but not desiccated. Activa Bioactive Restorative material was injected into the Bioclear matrix system so that it created a monolithic filling of the aquarium, working to minimize any bubbles during the injection process (Fig. 10). The material was then light cured from the buccal and the lingual 30 seconds per side after waiting 20 seconds for the material to stay in contact with the tooth structure being restored.

Fig. 5

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Fig. 10

The excess material was trimmed to occlusion and contour with discs and rotary composite carbides (Fig. 11). The restoration was then polished using BioClear Miracle Mix Pre-Polish and then Microcopy Gazelle Nanocomposite rotary polishing cups (Satin and Hi-Gloss Polishers) (Fig. 12). The final result (Fig. 13) was designed to work with the lower misaligned occlusion and provide a very nice final, conservative aesthetic result in a single visit without the need to reduce the remaining tooth structure significantly. The patient was given post-operative instructions and advised to consider orthodontic treatment to potentiality improve the alignment of the lower teeth to reduce potential for trauma to her dentition in the future. The patient was very pleased with her results.

Fig. 11

Fig. 12

Fig. 13

In conclusion, it is clear from the data presented, that there is a need to consider a new direction in our restorative methodology. The use of a bioactive material that can reduce enzymatic initiation by the tooth and can encourage biomineralization can provide superior benefits to traditional resin-bonding procedures. We now have the ability to restore any damaged tooth with materials a that can “heal and seal” the injured structure of that tooth, while at the same time provide a very effective highly polishable, wear resistant and resilient material that provides esthetic and functional final restoration. OH

Oral Health welcomes this original article.

1. http://idioms.thefreedictionary.com/accidents+will+happen
2. Jeffries SR. Bioactive and biomimetic restorative materials: a comprehensive review Part l. Esthet Restor Dent 2014;26(1):14-26.
3. NIDCR Strategic Plan 2009–2013. http://grants.nih.gov/grants/guide/rfa-files/RFA-DE-10-004.html#PartII.
4. Chow & Vogal. Enhancing Mineralization Operative Dentistry Supplement 6, 2001, 27-38E. Couve, R. Osorio, O. SchmachtenbergThe Amazing Odontoblast Activity, Autophagy, and Aging. JDR, June 26, 2013 (online)
5. Chaussain-Miller,et al. The role of Matrix Metalloproteinases (MMP’s) in Human Caries. J Dent Res 2006; 1:22-32.
6. Pashley DH, Tay FR, Imazato S. How to increase the durability of resin-dentin bonds. Compend Contin Educ Dent. 2011 Sep;32(7):60-4, 66.
7. Mazzoni, Tjäderhane, Checchi, Di Lenarda, Salo, Tay, Pashley, Breschi. Role of Dentin MMPs in Caries Progression and Bond Stability. JDR February 2015 vol. 94 no. 2 241-251. 8. http://www.pulpdent.com/activa-bioactive-white-paper/

About the Author
Dr. Comisi has been in private practice in Ithaca, NY since 1983, and is President and CEO of Dental Care with a Difference®, PC, President and CEO of Sleep Focused Solutions, Inc. and is a Clinical Instructor in Dentistry at the University of Rochester School of Medicine and Dentistry.

He is a graduate of Northwestern University Dental School and received his Bachelor of Science in Biology at Fordham University. Dr. Comisi is a Master of the Academy of General Dentistry, and holds Fellowships in the Academy of Dentistry International, the American College of Dentists, the Pierre Fauchard Academy and the International College of Dentists.

He is an Editorial Board Member for Dental Product Shopper magazine, a member of the Editorial Advisory Board of Dental Products Report and a Continuing Education Advisory Board member of Dental Learning. Dr. Comisi is a member of the National Dental Practice Based Research Network (NDPBRN) and the International and American Association of Dental Research. He also serves as a Scientific Advisory Board member of the Dental Biomaterials Science and Research Group and a member of the Scientific Advisory Board of Izun Pharmaceuticals.

His practical approach to the trends in dentistry has made him a much sought after speaker, author and consultant in the dental industry. He brings a passion and a knowledge base that is refreshing and sincere.