**5.5 Reconstruction of dental restorations**

Rebuilding of removed restorations should be started after complete elimination of all allergy-positive metal elements and the confirmation of no further relapse of symptoms. New restorations have to be made using allergy-negative materials for each of the individual patients. Since very small amounts of the element could cause an allergic symptom, all materials have to be tested to ensure that every micro component is allergy free. Since the reliability of the patch-test results have not been proven to be perfect, allergy-negative metal elements could still potentially cause allergy symptoms. Thus, during the reconstruction of dental prostheses, the initial restoration should be attached with temporary cement, and the patient prognosis followed for at least one month to ensure there are no allergy symptoms. In the case of a patient with a zinc allergy, careful selection of the luting cement is required. Zinc phosphate, zinc oxide eugenol, polycarboxylate cements along with most of the materials utilized for root canal fillings all have a zinc component and thus, cannot be used.

Lately, there have been many new products for dental restoration that have been developed and introduced in the market. Some of the new products that are listed below might potentially be useful for dental treatments of metal allergy patients.

#### **5.5.1 Titanium**

Since titanium possesses a fine biocompatibility property, this material has been used for pacemakers and dental implant biomaterials. Pure titanium can also be used for the material to fabricate a full veneer crown and fixed prostheses of the metal allergy patient. However, it should be noted that titanium wire used for orthodontic treatments contains a nickeltitanium alloy, and is not acceptable for nickel allergy patients.

#### **5.5.2 Highly polymerized compounds**

#### **5.5.2.1 Hybrid ceramics**

Recent progress of micro fillers and matrix components have greatly improved the physical property of light curing resin products. This newly developed product could potentially be applied in many clinical situations. The following table lists the official properties of the light curing resins currently on the market.

breathed in, or taken up by the oral mucosa during the removal procedure. In most cases, these symptoms are transient and the patient will recover within a couple of weeks. To avoid the possibility that a patient will develop such symptoms, all metal dust needs to be carefully excluded with oral evacuation equipment along with the adoption of the rubber dam dry field technique, whenever possible. In cases where allergy free metal materials are available, the final prosthesis using such metal material should be avoided until all allergy-positive metal materials have been removed. Additional metal restoration can increase the number of different metal elements in the oral cavity under certain circumstances, which may accelerate the elution of metallic ions from an allergy-positive

Rebuilding of removed restorations should be started after complete elimination of all allergy-positive metal elements and the confirmation of no further relapse of symptoms. New restorations have to be made using allergy-negative materials for each of the individual patients. Since very small amounts of the element could cause an allergic symptom, all materials have to be tested to ensure that every micro component is allergy free. Since the reliability of the patch-test results have not been proven to be perfect, allergy-negative metal elements could still potentially cause allergy symptoms. Thus, during the reconstruction of dental prostheses, the initial restoration should be attached with temporary cement, and the patient prognosis followed for at least one month to ensure there are no allergy symptoms. In the case of a patient with a zinc allergy, careful selection of the luting cement is required. Zinc phosphate, zinc oxide eugenol, polycarboxylate cements along with most of the materials utilized for root canal fillings

Lately, there have been many new products for dental restoration that have been developed and introduced in the market. Some of the new products that are listed below might

Since titanium possesses a fine biocompatibility property, this material has been used for pacemakers and dental implant biomaterials. Pure titanium can also be used for the material to fabricate a full veneer crown and fixed prostheses of the metal allergy patient. However, it should be noted that titanium wire used for orthodontic treatments contains a nickel-

Recent progress of micro fillers and matrix components have greatly improved the physical property of light curing resin products. This newly developed product could potentially be applied in many clinical situations. The following table lists the official properties of the

metal element.

**5.5.1 Titanium** 

**5.5 Reconstruction of dental restorations** 

all have a zinc component and thus, cannot be used.

potentially be useful for dental treatments of metal allergy patients.

titanium alloy, and is not acceptable for nickel allergy patients.

**5.5.2 Highly polymerized compounds** 

light curing resins currently on the market.

**5.5.2.1 Hybrid ceramics** 


Table 4. The official property of hybrid ceramics

#### **5.5.2.2 Rebuilding materials for an abutment tooth**

The combination of a composite resin for rebuilding and glass fiber has been used for an alternative to metal core rebuilding. Both a direct and indirect method can be used to fabricate the fibrous post using these materials.

The following are materials that can be used for fibrous posts.

5.5.2.2.1 FiberKor Post system (Pentron Clinical Technologies)

Type S glass fiber (10 µm in diameter) has a high physical property and is bundled up in matrix resin in order to make up the fibrous post used in the rebuilding. Components of the fibrous post are glass fiber (42%), filler (29%) and matrix resin (29%).

5.5.2.2.2 FIBER POST (GC Corp.)

Glass fibers that have a diameter of 14 µm are bundled lengthwise to create high density within the resin matrix. This material contains 58 vol% (77 wt%) of uniformed glass fiber.

5.5.2.2.3 CLEARFIL® FIBER POST (Kuraray)

Premier® Integra Fiber Post (Premier Products Co.)

This product contains 68% pre-silanated Zirconia-rich glass fibers within a composite matrix.

5.5.2.2.4 FRC Postec (Ivoclar Vivadent)

#### **5.5.3 Ceramic materials**

The progress in the field of ceramic materials has been quite remarkable as of late. Some of the all-ceramic restoration systems now on the market have a fine biostability and aesthetics that are suitable for use in treating metal allergy patients. With the development of computer-aided design and computer-aided manufacturing (CAD/CAM), all ceramics restorations with aluminous and zirconium coping have become the practical choice for esthetic prostheses (Fig. 12, 13). The zirconium ceramic systems in particular possess fine

Dental Metal Allergy 103

(a) zirconium frame (Cercon, DeguDent)

(b) Forming of porcelain on zirconium frame (c) Finished porcelain fused-to-zirconium

The subject was an inpatient of the Dermatological Clinic of Tokushima University Hospital. Results of the patch test at the clinic revealed that the patient had a nickel, cobalt, iridium, zinc, manganese and platinum allergy. The figure 14 shows a picture of the patient's right palm at her initial visit to the Dental Metal Allergy Clinic. Anti-allergic medication and

At the time she was seen in the clinic, the zirconium ceramic system for complete oral reconstruction was not on the market. Therefore, a semi-fixed prosthesis with four piece

Fig. 12. Example of zirconium blocks, zirconium frame before and after the sintering

procedure, and the finished all ceramic crown.

Fig. 13. Example of zirconium crowns.

**6.1 Case 1: 51-year-old female with dyshidrotic eczema** 

steroid ointment did not result in recovery from her allergic symptoms.

**6. Clinical cases** 

Prognosis

crowns

physical properties with regard to toughness and strength, with some products able to be applied for use in a complete oral reconstruction. The following table lists all of the main ceramic system products that are currently on the market.


Table 5. Ceramic system products

physical properties with regard to toughness and strength, with some products able to be applied for use in a complete oral reconstruction. The following table lists all of the main

In-Ceram Alumina Vita Al2O3,La2O3

In-Ceram Zilconia Vita Al2O3, ZrO2

IPS Empress Ivoclar Vivadent Leucite

IPS Empress2 Ivoclar Vivadent Leucite

Cergo Degdent Leucite

Finesse All-Ceramic Dentsply Ceramo Leucite

GN-1 GC Al2O3

Procera Nobel Biocare ZrO2

Cercon DeguDent ZrO2

Lava 3M ESPE ZrO2

Katana Noritake ZrO2

Everest ZS KaVo ZrO2

ZENO Zr Discs WIELAND ZrO2

Aadva Zr GC ZrO2

Cerium Nano Zilconia Panasonic Dental ZrO2

Decsy Digital process Leucite

IPS e.max CAD Ivoclar Vivadent Lithium disilicate

System Wol-Dent Al2O3,ZrO2

OPC/OPC3G Pentron Leucit/Lithium disilicate

Cerec Sirona Glass ceramics, Llithium

disilicate, Polymers

processing Proprietary name Product name Chief ingredient

ceramic system products that are currently on the market.

Classification by

Slip Technique

Press molding

CAD/CAM

CAD/CAM

Yttria

Table 5. Ceramic system products

Electrophoresis Wol-Ceramn ELC

(a) zirconium frame (Cercon, DeguDent)

(b) Forming of porcelain on zirconium frame (c) Finished porcelain fused-to-zirconium

crowns

Fig. 12. Example of zirconium blocks, zirconium frame before and after the sintering procedure, and the finished all ceramic crown.

Fig. 13. Example of zirconium crowns.
