Neither amalgam nor alternative filling materials has been biocompatibility tested or side effect reported in the same way as pharmaceutics has been for a long time.
Although it is unusual, people can be allergic to and / or get local oral reactions because of (ingredients of) any of the materials below (except maybe ceramics), as well as to (ingredients of) amalgam (as mercury).
Even if it is not likely that ceramics cause allergy, the ceramic will have to be cemented in to the cavity and the cement can cause allergic reactions.

6.1 Composites.

Inexpensive. Tooth-coloured. When used when there is need for a new small filling composites is regarded as tooth-conservative ( DHHS 1993 p I - 45). Can shrink which could lead to micro-leakage and secondary-caries ( DHHS 1993 p II-1). Composites are highly technique sensitive ( DHHS 1993 p II-1 ) and therefore the result can differ widely dependent on the skill of the particular dentist. Hypothetical concern about possible side effects (other than allergy) from different components released from composites has been put forward.

6.2 Glass ionomer cement.

Inexpensive. Fairly tooth-coloured. Adheres to the teeth and releases fluoride all the time, both reducing risks of secondarycaries. When used when there is need for a new filling glass ionomer cement is regarded as very tooth-conservative ( DHHS 1993 p I - 21).Glass ionomer cements are technique-sensitive ( DHHS 1993 p II-2 ). Glass ionomer cements are not resistant to mechanical wear, that's why it is mainly used for small fillings and not for big fillings with great chewing stress. Some people who suspect that they have an amalgam-related illness report that they do not tolerate glass ionomer cement.

6.3 Ceramics.

Expensive, costs about the same as Gold. Tooth-coloured, can be very aesthetic. Both porcelain and glass are ceramics. Ceramics are technique-sensitive ( DHHS 1993 p II-3 ). They are resistant to mechanical wear, but a bit fragile and can crack in a FEW cases. When replacing amalgam fillings with ceramic inlays the cavity where the amalgam-filling was placed must be altered so there are no undercut - thereby loosing healthy tooth substance ( DHHS 1993 p I - 9).

6.4 Gold.

Expensive. Technically a very good material.
Dental gold is not pure gold. (It can contain some of these metals in it; Au, Pt, Pd, In, Ir, Fe, Cu, Ag, Sn, Zn.)
Small amounts of gold is liberated from the fillings and absorbed by the body. However gold is not as toxic as mercury. When replacing amalgam fillings with gold inlays the cavity where the amalgam-filling was placed must be altered so there are no undercut - thereby loosing healthy tooth substance ( DHHS 1993 p I - 9 ).People suspecting that they have an amalgam-related illness often report that they do not tolerate gold, especially not when there still are amalgam-fillings left in the mouth (is this because of battery-effect -> increased corrosion-> increased mercury efflux from the amalgam-fillings?).

6.5 Recommendations from patient organisations.

To my knowledge there are no double-blind controlled studies, in humans with suspected (non-allergic-) amalgam-related illness, which could answer the question IF and then which alternative materials can potentially give side-effects and which are usually well tolerated. However patients (Tandvardsskadeforbundet 1993) as well as some dentists / physicians claims that there is a difference in how well tolerated different alternative filling materials are in this patient-group.

Swedish Association of Dental Mercury Patients says (Tandvardsskadeforbundet1994) that:

  • - Most composites function well in the majority of the patients, however Heliomolar and Helioprogress from Vivadent, Nulite-F, P-50 and Restorative Z-100 are the composites that sensitive individuals tolerate the best. But P-10 and P-30 (3M), Profile, Concise, Prisma-fil and Prisma fulfil, often give symptoms in sensitive patient-groups.
  • - Class ionomer cement is said to be a well tolerated alternative for many individuals, although again some sensitive individuals may not fully tolerate the metallic leakage from the cement. Recommended are: Fuji Inomer Type II (G-C Dental) and Ketac-Fil Aplicap (ESPE). Warned for are Ketac-Silver Aplicap (ESPE).
  • - Ceramics are usually well tolerated. Potential side-effects seems to be connected to the cement that has to be used to keep the ceramic in place. Recommended are: Ivoclar Empress, Dicor, Vitadur, Vita Inceram, Hi-Ceram, Duceram, Cerestore and Ecelco.
  • - Cement to glue the a ceramic in place, recommended are GC Fuji I (GC Dental) and Sonocem, but even Dualcement (Vivadent) is tolerated by the majority if isolated with a bonding as Gluma 2000 or Syntac:
  • - Gold is warned for.

Also make sure to read these books: Poison in Your Teeth: Mercury Amalgam (Silver) Fillings...Hazardous to Your Health! and Mercury Detoxification by Tom McGuire