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Sunday 19 December 2010

Clinical evaluation of dental restorative materials - Part II: Modified Ryge criteria

Cvar and Ryge criteria[1] for clinical evaluation of dental restorative materials were first published in 1971 and re-evaluated in 1980 by Ryge.[2] Another post explains the original Cvar and Ryge criteria in greater detail. Also, read about the new FDI criteria in a separate post.

Modified criteria, often called modified Ryge criteria are mostly used in contemporary clinical evaluations of dental restorative materials. Modifications usually depend on the aim of the study i.e. the type(s) of restorations that are being compared. Here are some studies reporting on clinical performance of restorative materials based on modified Ryge criteria.

Gallo et al.[3] conducted a three-year clinical evaluation of two flowable composites, Tetric Flow (Ivoclar Vivadent) and Esthet-X Flow (Dentsply/Caulk) which were used to restore Class I caries lesions. The authors used the original Cvar and Ryge criteria with two additional criteria: (1) retention and (2) polishability. Table 1 presents the codes and descriptions for each criterion. It should be noted that polishability is rated using more than the original 4 codes, introducing subtle differences in rating. This may, however, affect the variability of diagnostic judgement and intra- or inter-examiner reliability as it becomes more difficult to differentiate between e.g. Bravo B-a and B-b or C and D. Also, the term “unacceptable polish” comes as a rather unexpected vague description in contrast to detailed codes A-D and it is unclear what unacceptable means. For some dentists, “Rough and dull or satin, not reflective” may be completely “Unacceptable polish”. An obvious principle adopted by Cvar and Ryge in their original criteria should also be applied when modifying these criteria by introducing new ones – keep it simple.

Table 1. Codes and descriptions of two additional criteria, as used in Gallo et al.
(Click on the table)








Poon et al.[4] conducted a 3.5-year clinical evaluation of a packable (SureFil, Dentsply DeTrey) and a conventional (SpectrumTPH, Dentsply DeTrey) composite used with a self-etch adhesive system. Not only did the authors add more criteria, they also modified the descriptions of the original Cvar and Ryge criteria. Additional criteria were: (1) Retention, (2) Surface texture, (3) Surface staining, (4) Postoperative sensitivity and (5) Gingival bleeding in Class II restorations. All criteria in this study, with the exception of Postoperative sensitivity and Gingival bleeding, were rated as Alfa (A) or Bravo (B), where A was defined as “restorations meet all clinical standards with a range of excellence” and B was “though not ideal, restorations have a range of acceptability”. The rating for Postoperative sensitivity and Gingival Bleeding were “absent” or “present”.

Swift et al.[5] compared the 3-year clinical performance of two-step total-etch adhesives (OptiBond Solo, SDS Kerr and Prime & Bond 2.1, Dentsply Caulk). Their additional criteria were: (1) Retention, codes as in Table 1, (2) Postoperative sensitivity and (3) Other failure. The latter two were rated as “none” or “present”.

Moncada et al.[6] conducted a 3-year clinical trial to compare various treatment options for Class I and II restorations (sealed margins, repair, refurbishment, replacement or no treatment). Unlike previous cited papers, Moncada et al. did not use all of the original Cvar and Ryge criteria but selected only the following: (1) Marginal adaptation, (2) Anatomic form and (3) Caries. Also, they added two new criteria: (1) Surface roughness and (2) Luster, described in Table 2.

Table 2. Codes and descriptions of two additional criteria, as used in Moncada et al.
(Click on the table)















Kihn and Barnes[7] investigated clinical longevity of porcelain veneers after 4 years. They substituted Anatomic form from the original Cvar and Ryge criteria with Postoperative sensitivity which was rates “absent” or “present”.

Hamilton et al.[8] used modified Ryge criteria to evaluate pit and fissure restorations after 1 year of clinical service. Instead of the original Caries criterion, the authors added Surface smoothness which was rated as follows:

A - As smooth as natural adjacent tooth structure
B - Not as smooth as natural tooth structure but not pitted
C - Not as smooth as natural tooth structure and pitted

Hamilton et al.[8] also modified Margin discoloration and Margin adaptation to include subrating as described in Table 3. Quantification of discoloration along the margin was used and restorations rated as B1 for less than 50% of exposed margin or B2 for greater than 50% of exposed margin. A subtle one-way catch with an explorer during the assessment of margin adaptation was tolerated and rated as A2 instead of B. Also, code D for margin adaptation (Restoration mobile, fractured or missing in part of the tooth) was not taken into account, most likely because none was found.

Table 3. Modifications of the original Cvar and Ryge criteria by Hamilton et al.
(Click on the table)










Conclusions

Based on this short literature review, it is apparent that in contemporary clinical evaluation of restorative materials and treatment modalities, the original Cvar and Ryge criteria are modified in some way based on study objectives. These modifications include:

(1) Additional criteria are introduced: Retention, Polishability, Postoperative sensitivity, Surface roughness, Surface staining, Luster, Gingival bleeding; 

(2) Not all of the original Cvar and Ryge criteria are used; 

(3) Subrating are introduced to increase the precision of clinical judgment or the quality of the original criteria is reduced either through poorer description of rating or by excluding rating.

Despite the limitations, Cvar and Ryge rating scales, with or without modifications, remain the most frequently used method of clinical evaluation of dental restorative materials and operative techniques.

References
1. Cvar and Ryge criteria for the clinical evaluation of dental restorative materials. First published in U.S. Department of Health, Education, and Welfare, U.S. Public Health Service 790244, San Francisco Printing Office 1971:1–42. Reprinted in Clinical Oral Investigations 2005;9:215–232.
2. Ryge G. Clinical criteria. Int Dent J 1980;30:347-58
3. Gallo JR, Burgess JO, Ripps AH, Walker RS, Maltezos MB, Mercante DE, Davidson JM. Three-year clinical evaluation of two flowable composites. Quintessence Int. 2010 Jun;41(6):497-503.
4. Poon EC, Smales RJ, Yip KH. Clinical evaluation of packable and conventional hybrid posterior resin-based composites: results at 3.5 years. J Am Dent Assoc. 2005 Nov;136(11):1533-40.
5. Swift EJ Jr, Perdigão J, Wilder AD Jr, Heymann HO, Sturdevant JR, Bayne SC. Clinical evaluation of two one-bottle dentin adhesives at three years. J Am Dent Assoc. 2001 Aug;132(8):1117-23.
6. Moncada G, Martin J, Fernández E, Hempel MC, Mjör IA, Gordan VV. Sealing, refurbishment and repair of Class I and Class II defective restorations: a three-year clinical trial. J Am Dent Assoc. 2009 Apr;140(4):425-32.
7. Kihn PW, Barnes DM. The clinical longevity of porcelain veneers: a 48-month clinical evaluation. J Am Dent Assoc. 1998 Jun;129(6):747-52.
8. Hamilton JC, Dennison JB, Stoffers KW, Welch KB. A clinical evaluation of air-abrasion treatment of questionable carious lesions. A 12-month report. J Am Dent Assoc. 2001 Jun;132(6):762-9.

Monday 13 December 2010

Clinical evaluation of dental restorative materials - Part I: Cvar and Ryge criteria

Nearly 40 years ago John F. Cvar and Gunnar Ryge wrote that, although mechanical properties of the available dental restorative materials were well known, clinical scientific data were scarce. The lack of evidence-based studies was the result of the lack of well-defined measures to evaluate the clinical performance of dental materials. As a fast and relatively reliable solution, Cvar and Ryge developed the rating scales which assess five characteristics of dental restorative materials indicative of their aesthetics and functionality.(1) With some modifications, these criteria are still used in clinical evaluation of dental materials and operative techniques. Read about modified criteria and the new FDI criteria in separate posts.

The original Cvar and Ryge criteria or characteristics used for material clinical evaluation are color match, cavo-surface marginal discoloration, anatomic form, marginal adaptation and caries. Codes Alfa, Bravo, Charlie and Delta are used to rate the restorations according to the assigned descriptive values for each characteristic (Table 1). The rating is conducted in a clinical setting, usually by two examiners (dentists) and a recorder (e.g. dental assistant), by visual inspection of the restoration with the use of a mirror if necessary. In addition, an explorer is used to rate marginal adaptation and the presence of caries.

In 1980, Ryge published another paper on clinical criteria in which he systematically set out an approach in clinical assessment of restorative materials using the original Cvar and Ryge criteria.(2) In addition to the previously developed rating scales, Ryge introduced a classification of restorations. The four categories are:
  1. Restorations within a range of excellence,
  2. Restorations which are acceptable although showing minor deviations from the ideal,
  3. Restoration which should be replaced for preventive reasons to avoid the likelihood of future damage and
  4. Restorations which require immediate replacement.

Table 1. Original Cvar and Ryge criteria used to evaluate non-metallic restorations. (Click on the table)























References

1. Cvar and Ryge criteria for the clinical evaluation of dental restorative materials. First published in U.S. Department of Health, Education, and Welfare, U.S. Public Health Service 790244, San Francisco Printing Office 1971:1–42. Reprinted in Clinical Oral Investigations 2005;9:215–232.

2. Ryge G. Clinical criteria. Int Dent J 1980;30:347-58

Tuesday 30 November 2010

ADA: WHO releases report on dental materials, amalgam

American Dental Association - WHO releases report on dental materials, amalgam

Dental amalgam is rapidly fading out from dental practice due to the increased use of aesthetic restorative materials, particularly resin-based composites, for restorations in posterior teeth. However, the debate about the safety of dental amalgam seems to be a never-ending subject. Amalgam opponents go as far as to request this material to be banned due to the toxicity and health issues associated with mercury (oral lesions, autoimmune disorders, chronic illnesses etc.)

In a recent report, the World Health Organization (WHO) states that dental amalgam remains a dental restorative material of choice reaffirming the safety of this material. Nevertheless, the WHO report emphasizes that alternative materials and preventive measures should be further improved and implemented.

In 2009, ADA and FDA agreed that dental amalgam should not be restricted from dental practice since the scientific literature supports amalgam as "a valuable, viable and safe choice for dental patients". Read more about this in another post.

It seems that amalgam will eventually cease to be used in dentistry not because of its safety issues but because of considerable improvements of aesthetic materials.

Monday 15 November 2010

Mineral Trioxide Aggregate (MTA): Free full text articles II

To see previously published list of free full text articles on MTA (part I), please click here.

Endodontics - Case reports

Unal GC, Maden M, Isidan T. Repair of Furcal Iatrogenic Perforation with Mineral Trioxide Aggregate: Two Years Follow-up of Two Cases. Eur J Dent. 2010 Oct;4(4):475-81.  

Yildirim T, Gencoglu N. Use of mineral trioxide aggregate in the treatment of large periapical lesions: reports of three cases. Eur J Dent. 2010 Oct;4(4):468-74.

Abarajithan M, Velmurugan N, Kandaswamy D. Management of recently traumatized maxillary central incisors by partial pulpotomy using MTA: Case reports with two-year follow-up. J Conserv Dent. 2010 Apr;13(2):110-3.

Chhabra N, Singbal KP, Kamat S. Successful apexification with resolution of the periapical lesion using mineral trioxide aggregate and demineralized freeze-dried bone allograft. J Conserv Dent. 2010 Apr;13(2):106-9.

Adiga S, Ataide I, Fernandes M, Adiga S. Nonsurgical approach for strip perforation repair using mineral trioxide aggregate. J Conserv Dent. 2010 Apr;13(2):97-101.

Ozbas H, Subay RK, Ordulu M. Surgical retreatment of an invaginated maxillary central incisor following overfilled endodontic treatment: a case report. Eur J Dent. 2010 Jul;4(3):324-8.

Araújo RA, Silveira CF, Cunha RS, De Martin AS, Fontana CE, Bueno CE. Single-session use of mineral trioxide aggregate as an apical barrier in a case of external root resorption. J Oral Sci. 2010;52(2):325-8.

Khatavkar RA, Hegde VS. Use of a matrix for apexification procedure with mineral trioxide aggregate. J Conserv Dent. 2010 Jan;13(1):54-7.

Mirikar P, Shenoy A, Mallikarjun GK. Nonsurgical management of endodontic mishaps in a case of radix entomolaris. J Conserv Dent. 2009 Oct;12(4):169-74.

Endodontics - scientific articles
Orosco FA, Bramante CM, Garcia RB, Bernardineli N, de Moraes IG. Sealing ability, marginal adaptation and their correlation using three root-end filling materials as apical plugs. J Appl Oral Sci. 2010 Mar-Apr;18(2):127-34.

Biocompatibility
Lessa FC, Aranha AM, Hebling J, Costa CA. Cytotoxic effects of White-MTA and MTA-Bio cements on odontoblast-like cells (MDPC-23). Braz Dent J. 2010 Jan;21(1):24-31.

Cintra LT, Bernabé PF, de Moraes IG, Gomes-Filho JE, Okamoto T, Consolaro A, Pinheiro TN. Evaluation of subcutaneous and alveolar implantation surgical sites in the study of the biological properties of root-end filling endodontic materials. J Appl Oral Sci. 2010 Feb;18(1):75-82.

Chemical analysis

Han L, Okiji T, Okawa S. Morphological and chemical analysis of different precipitates on mineral trioxide aggregate immersed in different fluids. Dent Mater J. 2010 Oct 14;29(5):512-7.

Thursday 11 November 2010

Silorane technology in restorative dentistry - material properties and clinical application

I recently published a review article in the Serbian professional journal "Stomatolog" ["Dentist"] on Filtek Silorane material properties and clinical application steps. The article is in Serbian but I would be happy to translate it to English for interested colleagues. Contact me at vesna.miletic@gmail.com

Abstract

Polymerization shrinkage remains one of the main weaknesses of composite materials. Silorane technology significantly reduces material shrinkage compared to methacrylate composites. This review article compares chemical composition and polymerization process of methacrylate- and silorane-based composites. Systematically are reviewed studies on mechanical, aesthetic, antibacterial and chemical properties of Filtek Silorane, as well as its interaction with tooth tissues. Lower polymerization shrinkage and microbial adherence and comparable mechanical properties have been reported for Filtek Silorane compared to methacrylate-based composites. In the only clinical study that has been published so far, marginal adaptation of Filtek Silorane was found to be inferior than the nanocomposite Ceram.X  However, low inter-examiner reliability questions the results of this clinical study and scientific literature lacks more information on clinical performance of Filtek Silorane. 

Wednesday 13 October 2010

Monomer elution from a dental composite

Recently, I started a series of studies on monomer elution from composites with colleagues from University of Belgrade School of Dentistry and Faculty of Technology and Metallurgy. One of these experiments was presented a month ago at an international material science and engineering conference YUCOMAT.

The nano-hybrid composite Filtek Z250 (3M ESPE) was used to study elution kinetics of monomers UDMA and HEMA over 28 days post-immersion in either distilled water or 75% ethanol. Kinetic models were proposed and it was shown that monomer elution followed the first order law for both UDMA and HEMA irrespective of the medium. However, there were some differences in that UDMA eluted more rapidly during the first 24 h and then much more slowly over the 28-day period. This indicates that during the first 24 h elution from the sample surface occurred whereas the slow phase corresponds to monomer elution from inside the polymer. On the other hand, HEMA did not start to elute immediately, but only after 24 h and the eluted concentrations increased over the 28 days. Though HEMA is not a genuine ingredient of the studied composite, its slow elution and small eluted amounts seem to support a previous statement by other authors that HEMA could elute as a product of degradation of UDMA. (We are currently investigating this hypothesis.)

Monday 4 October 2010

Dental Materials Blog: Year 1

It has been a year since I started writing on this blog. During this first year, nearly 6700 visits and 12000 pageviews have been made by more than 5300 unique visitors. The average number of visits per day has been increasing constantly and currently is 17.70. What I am particularly proud is that one fifth of all visitors have returned and visited the blog more than once. Another important figure is that visitors come from more than 120 countries in the world (Figure 1.). The importance of this information is not so much related to the blog itself, but shows that in almost every corner of the Earth people search for dental information and want to expand their knowledge.
Figure 1. Map overlay

The most frequently visited posts are related to MTA in endodontics and the list of free full texts, self-adhering composite Vertise Flow and nano-filled, resin-modified glass ionomer Ketac N100. Likewise, the most frequently used keywords are "dental materials", ""MTA dental material", ""MTA dental", "mineral trioxide aggregate",  "Vertise Flow"...

Comments were disabled for most of the year, because I haven't noticed there was a problem, but a visitor drew my attention to it. Comments are now fixed and those received so far are all very positive.

I would like to encourage fellow researchers and clinicians to contribute to the Dental Materials Blog with their own posts, it is free and the choice of topics is entirely up to the authors.