Reinforcing Teeth In The Restorative Process: New Thinking On Dentin’s Role

What Is Root Canal Therapy (RCT)?
This is the treatment of choice most used by dentists to deal with dentin in the case of infection in tooth decay. The infected tooth is opened at the crown to allow access to the root canal. The infected material is excised and the area cleaned. The canal itself is enlarged in preparation for filling material. A temporary dental filling may be employed. This will be replaced with a permanent filling once the tooth has healed. A crown can, then, be affixed over the tooth to protect it from further damage.
Why The Rubber Dam?
“RCT must always be performed with rubber dam isolation in place . In some cases this can be in the form of a rubber dam cuff which will allow visualisation of the orientation of the long axis of the tooth to assist in the access to the pulp chamber.”
– SA.ADA.org.au
The rubber dam creates a bacteria-free treatment zone, with saliva and blood stopped from entering the area. A dry treatment zone is preferable. It, also, provides protection from dental material or instruments from being swallowed by the patient.
Posts & Restorative Dentistry
The ultimate success of the final restoration is recognised, now, as dependent upon the preservation of dentin. The relevance of this in relation to fibre posts and tooth reinforcements cannot be underestimated. More enlightened dental thinking comprehends that the excessive removal of dentin support in the root and coronally changes flexural behaviours and weakens resistance to failure.
“Over-flaring the canal for straight-line access weakens the dentinal complex. Maintaining coronal dentin is crucial not only for supporting the core buildup but also because clinical and in vitro studies show that the survival of endodontically treated teeth restored with posts directly depends on the amount of residual coronal dentin.”
– Dental News
New Thinking On Dentin in Posts
New thinking on dentin’s role is specifically that the post preparation of the root canal must discourage additional removal of dentin. The elimination of parallel-sided posts from their procedural protocol is recommended, as they require removal of more dentin to form sharper internal line angles – this increases chances of root fractures. The parallel post, which was widely taught in the past, does not complement the tapered shape of the prepared canal and there are resultant issues due to this mismatch.

1989 is indicated as the year that posts were first introduced to clinical dental practice in France. 1990 saw research on dental fibre posts published by Duret.
“Due to their suitable mechanical properties, such as tensile strength and stiffness, electrical conductivity, and low toxicity, carbon/graphite fibers were chosen for this application]. This material revolutionised dentistry since it was an efficient alternative to metal posts. The modulus of elasticity of these fiber-reinforced materials was closer to that of dentin than the previously used metal posts, and the results of clinical studies were promising. Since their introduction, they have gained popularity among dental clinicians due to their reliable clinical performance and variety of advantages, such as their mechanical, esthetic, and elastic properties. However, the initial posts did have a disadvantage in terms of esthetics, as they were still visible beneath restorations made entirely of ceramic or composite. With the incorporation of quartz and glass fibers into the resin, more radiopaque fiber posts have been developed over time.”
– Alshabib A, Abid Althaqafi K, AlMoharib HS, Mirah M, AlFawaz YF, Algamaiah H. Dental Fiber-Post Systems: An In-Depth Review of Their Evolution, Current Practice and Future Directions. Bioengineering (Basel). 2023 May 4;10(5):551. doi: 10.3390/bioengineering10050551. PMID: 37237621; PMCID: PMC10215107.
Endodontic & Post-Debonding Failures
Endodontic refers to dentin.
“The term endodontics is derived from two Greek words – “endo” meaning inside and “odons” meaning tooth. Taken together, these words mean study of the inner part of the tooth or the dental pulp. Endodontics specialists are familiar with a number of diseases that involve the dental pulp and the procedures to treat them.”
– Medical News
The failure rate, reported in a recent overview study into posts and restorative dentistry ranged from 2% to 40%. Many variables contributed to these failures. Such as the type of teeth restored, anatomical variability in root canals, types of luting cement, and whether direct or indirect final restorations. Post-debonding failures were the most prevalent and endodontic failures the next most prevalent. Rates were low, however, in the 2%-3% band for post-related failures.
“Regardless of the material used to fabricate the post, the lengthier they are, the longer they will survive. There is a proportional relationship between frictional retention and the contact area; the greater the contact area, the higher the retention level. This finding explains the results of the macro push-out and pull-out tests in which the entire post became detached.”
– PMC.NBCI
Restoring Broken Endodontically Treated Teeth
The circumferential ferrule, which is defined as a metal band or ring that encircles the tooth to provide retention and resistance to fracture, is key here. In the restorative treatment of endodontically broken teeth a 2mm circumferential ferrule is recommended for improving resistance to fractures. Therefore, the height of the remaining dentin plays a part here and most crucially its width too.
“When investigating the fracture resistance and failure mode of premolars restored with composite resin and various prefabricated posts Hajizadeh et al. (1) utilized 60 extracted teeth with four subgroups: no cavity preparation, endodontics with an MOD and no post, endodontics with a DT Light Post (RTD) and MOD, and the last group with endodontics, Filpost (Filhol Dental, Gloucestershire, UK) and an MOD composite restoration. The teeth restored with the DT Light Post and composite were as strong as the control (the unprepared tooth) and stronger than those teeth restored with composite alone without a post, and those restored with a Titanium post and composite. In the DT Light Post group, 86% of the fractures were “restorable”, which was much higher than any of the other three groups. According to the authors, “There is growing evidence that fiber posts provide the additional benefit of increased fracture resistance.” “
– Dr. Len Boksman, Dr. Gary Glassman, Dr. Santos, Dr. Manfred Friedman in Dental News: The Role of Posts in Restorative Dentistry
Reinforcing teeth in the restorative process is the new thinking on dentin’s role. Dentin is the living material inside our teeth and greater respect being paid to that fact is transforming many dental procedures like root canal therapy. The future looks bright when more dentin is preserved and protected.
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Services We Mentioned:

Restorative Dentistry

Dental Crowns
