Summary � Where have we come from? � What do we currently have? Discussion on choices of and � Where could we be heading? advances in dental materials Where have we come from? Cohesive gold � Pre 1960 Restorations 60 years old � Gold when photographed � Amalgam � Zinc phosphate / Zinc oxide & Eugenol � Bowen’s resin (BIS-GMA) 1955 � 1960 � Adhesion to enamel � 1980 � Glass ionomer chemistry � Composite bonding to enamel � 1990 � Dentine bonding � 2000 � No etch bonding and the rise of the posterior composite Amalgam Zinc phosphate
Composite resin Composite resin Glass Ionomer Cement Zinc polycarboxylate cement Zinc cement - glass Zinc Polyacrylic polyalkynoate spectrum oxide acid Glass ionomer Glass ionomer Zinc phosphate Zinc phosphate cement cement cement cement Alumino- Phosphoric slilcate acid glass Silicate cement Amalgam What do we currently have?
Do teeth with amalgam have a high incidence of cuspal fracture? � No � 1.5% in 600 teeth after 5 years � 1.8% in 1400 teeth after 10 years � 5% in 1213 teeth after 15 years � Bonded amalgams may fare even better Whal Dental Update 2003;30:256-262 Do temperature changes in amalgam cause Do teeth with amalgam restorations have a cusp fracture higher rate of recurrent decay? � No � No � Coefficient of thermal expansion of resin is � 0% of 600 teeth at 5 years greater than amalgam � 1.1% of 1400 teeth at 10 years � No prolonged contact with temperature extremes before swallowing � 0% of 35 teeth at 10 years � Of greater importance is tooth preparation and � <5% after 14 years (no nos.) parafunction Aren’t bonded restorations preferable to Do resin composite restorations usually amalgam restorations last as long as amalgam restorations? � Yes � No � 2001 study � Composite bonded to enamel and dentine creates � 12 yrs = median age 1827 failed amalgams a monoblock whereas amalgam may create a � 5 yrs = median age of 1548 failed composites wedge � 2000 study of 6761 teeth � Increasing numbers of dentists are bonding � median age of replaced amalgam = 10 yrs � and composite = 8 yrs amalgam restorations � amalgam lasting longer than composite in C I, II III IV and V � Some evidence of good bond strength of amalgam restorations � 1998 study to dentine � median age of amalgam replacement = 15 yrs, � composite = 8 yrs
Amalgam is over 100 years old – doesn’t Has amalgam been banned in Sweden and that make it old fashioned? Germany? � No � No � So is radiography, nitrous oxide, gold and � Amalgam use in the EU is governed by rubber dam Medical Devices Directive 93/42/EEC. � High copper formulations, factory measured � 1998 EU working group stated, “no scientific components, pre-capsulated amalgam evidence of systemic health problems or toxic effects from dental amalgam. Do amalgam restoration release a large Does mercury from amalgam restorations amount of mercury? cause ill health? � No – except rare cases of allergy (Eg Lichenoid � No reaction) � It is estimated that a patient would have to have � Sandborgh-Englund G, Nygren AT, Ekstrand J, Elinder C-G. No evidence of renal toxicity from amalgam fillings. Am J Physiol 1996 ; 271: R941–945. 2740 amalgam restorations to reach the threshold � Saxe SR, Wekstein MW, Kryscio RJ et al. Alzheimer’s disease, dental amalgam and mercury. J Am Dent Assoc 1999 ; 130: 191–199. limit value of 82.20 microns per day considered � Casetta I, Invernizzi M, Granieri E. Multiple sclerosis and dental amalgam: case-control study in Ferrara, Italy. Neuroepidemiology 2001 ; 20: 134–137. dangerous for occupational exposure in the USA � Rodvall Y, Ahlbom A, Pershagen G et al. Dental radiography after age 25 years, amalgam fillings and tumours of the central nervous system. Oral Oncol 1998 ; 34: 265–269. � Lindberg NE, Linberg E, Larsson G. Psychologic factors in the etiology of amalgam illness. Acta Odontol Scand 1994 ; 52: 219–228. � Björkman L, Pedersen NL, Lichtenstein P. Physical and mental health related to dental amalgam fillings in Swedish twins. Community Dent Oral Epidemiol 1996 ; 24: 260–267 Lichenoid reaction Desquamative gingivitis
Is mercury from dental amalgam Is there credible scientific literature that dangerous to dental staff? shows health problems due to mercury in dental amalgam? � No � No � “ the infants of dental workers actually had a lower perinatal death rate than the rest of the infants ” (Ericson A, Källén � Independent analysis of data shows incorrect B. Pregnancy outcome in women working as dentists, dental assistants or dental technicians. Int Arch Occup Environ Health 1989; 61: 329–333.) conclusions often drawn � “ In a study of 21 634 male dentists and 21 202 dental assistants there was no difference in the rate of � Data extrapolating snail cells to human clinical spontaneous abortions or congenital abnormalities ” (Brodsky JB, Cohen EN, Whitcher C et al . Occupational exposure to mercury in dentistry and pregnancy response outcome. J Am Dent Assoc 1985; 111: 779–780.) � Of 1706 dentists screened at a 1991ADA meeting, only 29 � Exposure to Hg levels x100 normal levels (2%) had high urinary mercury levels. These high levels were correlated to poor mercury hygiene ( the use of squeeze cloths ). (Echeverria D, Heyer NJ, Martin MD et al. Behavioral effects of low-level exposure to Hg among dentists. Neurotoxicol Teratol 1995; 17: 161–168.) Are the ingredients of resin composite Are the ingredients of resin composite non-toxic? non-toxic? � No � Composite restorations have been shown to leach � The ingredients of resin composite have been shown between 14 and 22 separate potentially hazardous to be compounds, including � cytotoxic � DLcamphorquinone, � mutagenic � 4-dimethylaminobenzoic � To cause immunosuppresion or � acid ethy ester (DMABEE), drometrizole, � to inhibit DNA85 and RNA86 synthesis. � 1,7,7-trimethylbicyclo[2,2,1]heptane, 2,2- � Wataha et al. stated, � dimethoxy[1,2] diphenyletanone (DMBZ), � ‘the components of resin composites are hazardous in that � ethyleneglycol dimethacrylate (EGDMA), they all cause significant toxicity in direct contact with � and triethyleneglycoldimethacrylate (TEGDMA) fibroblasts . Does amalgam in waste water cause Is the death of amalgam imminent? harmful environmental effects? � Not yet……… � Probably not � Sig. number of dentists still use amalgam � Most amalgam from dental surgeries captured � Many patients prefer tooth coloured restorations by amalgam traps � Such patients do not tend to have health concerns � 3-4% of worldwide consumption of mercury is over amalgam for dental purposes � Estimated that 0.3% of amalgam waste is soluble
Amalgam when “ It may be prudent to consider ‘phasing down’ � Strength instead of ‘phasing out’ of � Bulk dental amalgam at this stage. A multi-pronged � Moisture control approach should be considered. Short-, medium- and long-term strategies should be developed.” 2009 meeting published2010 1. What is taught in UK dental schools Surveys � 1989 – worldwide survey – 90% schools do NOT teach posterior composite � 1998 – little change in American dental schools � 1997 – paper, use of composite in load bearing posterior cavities should be, “ ‘limited to the occlusal surfaces of premolars, and preferably those with limited occlusal function” Wilson N H F, Setcos J C. J Dent 1989; 17: S29 BDJ, 2010;209:129 Mjör I, Wilson N H F.. J Am Dent Assoc 1998; 129: 1415. Wilson N H F, Dunne S M, Gainsford I D. Int Dent J 1997; 47: 185. Surveys Guidelines � 2004 – 2005. 30% of posterior restorations � 2007 , British Association of Teachers of placed by dental students are composite Conservative Dentistry (BATCD) published a consensus document which recommended that � composite should be taught to dental students as the ‘material of choice’ when restoring posterior teeth, in particular when managing teeth with an initial lesion of caries Lynch C D, McConnell R J, Wilson N H F. Eur J Dent Educ 2006; 10: 38-43. Lynch C D, McConnell R J, Wilson N H F. J Am Dent Assoc 2006; 137: 619-625. Lynch C D, McConnell R J, Wilson N H F. J Can Dent Assoc 2006; 72: 321. Lynch C D, McConnell R J, Wilson N H F. J Dent Educ 2007; 71: 430-434.
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