A Simple Method to Protect Patient andEnvironment wlien Using Sandblasting for

Intraorai Repair

JoostJ. Roeters^

Abstract; Repair or correction of intraoral restorations can be an aiternative to complete replacement. A

simple sandblasting device is very effective in producing a microretentive surface on every restorative ma-

terial, A disadvantage of the technique is the production of an aerosoi contaminated with the smaii, atjra-

sive aiuminum-oxide particles. In this article, a simple solution is given to protect the patient and

environment against this dust during intraoral reparatory procedures involving sandblasting.

J AcJhes:ve Dent 2000:2:235-238. SuOmitted ior ßuaiicsüon:3Q.01.00: acceptea for publication:17.04.00.

In traditional dentistry, restorations which faileddue to fracture or loss of esthetics were com-

pletely replaced. Today, there are several tech-niques available allowing an intraoral correction orrepair of all types of restorations with a direct resincomposite.'^ Retention can be provided by macro-mechanical, micromechanica l , and chemicalmeans. Macromechanical retention means creatingundercuts, and this can be done in every restora-tive material. Micromechanical retention can beproduced by etching with hydrofluoric acid (porce-lain and composite) and by sandblasting (metal,porcelain, composite, and methylmethacrylates].Chemical retention can be enhanced by silanization(materials containing oxides) or special primers(metal and acrylic). Sandblasting has the advan-tage of being a simple and effective technique forcreating a microretentive surface on every restora-tive material. For this purpose, relatively simple andinexpensive equipment (e,g., Microetcher, DanvilleEngineering, Danville, CA, USA, and Handiblaster,Mirage Systems, Kansas City, KS, USA] is available.

^Assistant Professor, Department of Csriology, University ofNymegen. The Netherlands.

Reprint requests: Dr. Joost J. Roeters, College of Denla/ Science, De-partment of Csriology/117, University of Nymegen, P.O. Box 9101,6500 HB Nymegen, me Netherlands. Tel: +31-243616410, Fax; *31-243540265, e-mail: f.roeters®dentkun.ni

Also, the more sophisticated air-abrasion units maybe used for this purpose. The abrasive powder canbe aluminum oxide (27 to 250 pm) cr a special sil-ica-containing powder (Cojet, Espe, Seefeld, Ger-many). This powder crushes when it impacts on thesurface, and remnants of the particles are embed-ded there. Because this substance is an oxide,silanization will provide additional retention.

A disadvantage of sandblasting is the aerosolproduced, which is difficult to control. A dentalaerosol is defined as suspensions of extremely fine(< 50 |jm) airborne particles that are liquid, solid, orcombinations of both.^ Aspiration of such smallparticles is considered to be unhealthy, since theyremain airborne for a longer time and are capableof penetrating deep into the respiratory tract. Con-tact with the eyes and contamination of dentalequipment should also be avoided. Ultrasonic unitssuch as sealers will also produce aerosols whichcontaminate the environment.^ However, suchaerosols can be well controlled by using large-bore,high-volume evacuators. The aerosol produced by asandblasting device has a different compositionand may spread over a longer distance. The particlesize of aluminum oxide or the sandblasted restora-tive material may be 50 pm or even less if the pres-sure is high. More sophisticated air-abrasion unitswhich are designed for cavity preparation are easierto control than a simple sandblaster. Such units areoften equipped with an external suction deviceused in addition to the high-volume suction, De-

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spite these precautions, the patient must be treat-ed under a rubber-dam, and the dentist and assis-tant should wear well-fitting masks to preventaspiration of the dust. Furthermore, the patient anddental personnei should wear protective glasses.

The following case report describes treatment in-volving a simple, inexpensive method that helpsprevent contamination of the environment with alu-minum-oxide powder during intraoral sandbiastingfor repair.

CASE REPORT

A 37-year-old woman was not satisfied with the es-thetics of her dentition (Fig 1). She had moderatetetracycline staining, but her chief complaint wasthe grayish shade of the metai-porcelain crowns onteeth 11 and 21. These restorations were only a fewyears old, and except for the esthetics, the crownswere functioning well. Due to the generaiized discoi-oration, replacement of the crowns alone wouid notbe sufficient to improve the esthetics. In the max-iiia, the iaterai incisors, canines, and - dependingon the smileline - also the first premolars shouldbe incorporated in treatment. Since the patient op-posed the idea of having these teeth crowned, thedecision was made to place direct composite ve-neers on ali the maxillary anterior teeth. The buccaisurfaces of 11 and 21 were ground using a dia-mond bur, and the grayish shade of the crowns ap-peared to be caused by the minimai thickness ofthe porcelain. Figure 2 depicts the crowns after re-movai of the thin porcelain layer. Enough metai wasground off to create sufficient space for the com-posite resin. The tooth reduction for the crown hadbeen insufficient, and the buccai metai was localiyperforated. To provide retention, it was necessary tosandblast the metai as follows.

In the bottom of a piastic bag (size 10/4 x 30cm), a 3 X 4 cm hole was cut with scissors. A 4 x 6cm piece of rubber-dam was taped over this hole(Fig 3). Using rubber-dam forceps, two hoies werepunched in the rubber-dam. The plastic bag wasrolled up, and the rubber-dam was pulled over thefirst maxillary incisors (Fig 4). Dental floss wasplaced around the crowns, and Wedjets (Hygenic,Akron, OH, USA) were inserted interproximaily to se-cure the rubber-dam, inside the bag, a cotton roliwas placed on the buccai and on the paiatal side ofthe alveolar process. The plastic bag is roiied downwhile holding the cotton rolls in piace with finger

pressure from outside the bag (Fig 5). The cottonrolls heip keep the rubber-dam in place. Then thedentai assistant opens the bag and places thesandblasting device inside the bag with the tipclose to the surface of the crowns (Fig 6). The den-tist grasps the sandbiasting device through the bag.The transparent piastic facilitates placement of thesandbiasting tip in the proper position. The assis-tant cioses the bag and keeps a large-bore, high-volume suction tube just outside the opening (Fig6); this tube shouid not be placed inside the bag,as the plastic would be suctioned onto the orifice ofthe tube. After sandbiasting for a few seconds, thebag and rubber-dam are removed; most of the alu-minum oxide is left inside the bag. By rinsing thesandblasted surface with water, further distributionof the dust can be prevented. The sandblastedrestorations are shown in Fig 7.

During restorative treatment, proper isoiationshouid be maintained, using either a rubber-dam orcotton rolls and suction in combination with Con-tourstrips (Vivadent, Schaan, Liechtenstein). In thiscase, a Contourstrip was piaced around each toothto isolate the tooth surface. An additional functionof the Contourstrip is that it contributes to the shap-ing of the restoration in the cervicai region. Thesandbiasted surfaces and the exposed dentin wereetched with phosphoric acid to clean the surfaceand enable adhesion to the dentin. A metai primerwas applied on the metal surface prior to a dentin-bonding agent, because this wili further enhanceadhesion,^ After polymerization of the bondingagent, the metal was covered with an opaque colormodifier. The teeth were restored with an anteriorhybrid composite resin in various shades and de-grees of translucency. Upon request of the patient,the maxiliary Iaterai incisors, canines, and first pre-molars were just siightiy ground before being re-stored with the same opaque color modifier andshades of composite as used on the centrai in-cisors. Due to the minimai preparation and theneed to restore translucency, slight overcontouringwas accepted. Figures 8 and 9 show the results oftreatment.

OISCUSSION

Contamination of the environment during sand-blasting is a major drawback to this technique. In-halation of fine dust particles is harmful for bothpatients and operators, but particuiariy for the den-

236 The Journal of Adhesive Dentistry

Figl Dentition before treatment. Fig 2 The crowns after removal of porcelain and part of themetal.

Fig3 Plastic bag modified with a piece of rubber-dam. Fig 4 The rubber-dam is secured with dentai fioss and Wed-jets.

Fie 5 R. olacine cotton rolls inside, the bag can be held in Fig 6 The sandblasting device is piaced inside the bag andplace w ? h S r p - ™ u r e , the assistant holds high-volume suction tube near the open-

ing of the bag.

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Roete rs

Figs 8 and 9 The result 4 months after restoration of the maxillary incisors and canines with direct composite veneers.

tist and assistant, since they are exposed more fre-quently. Furthermore, the abrasive powder willscratch the exposed surfaces of dental equipment.For those who do not want to invest in an expensiveair-abrasion unit for cavity preparation but want tobe abie to do repairs, a sandbiaster is a good in-vestment. The simple, inexpensive method de-scribed above prevents the dispersion of the finedust produced during sandblasting.

REFERENCES

1. Cooley RL. Aerosoi hazards. In: Goldman HS, Hartman KS,MessiteJ (eds). Occupationai hazards in dentsitry.ChicagciYear Beck Medicai Pubiishers,1984:21-23.

2. Harrel SK, Barnes JB, Rivera-Hidalgo F. Aerosoi end splattercontamination from the operative site during uitrasonic scal-ing J Am Dent Assoc 1998;129:1241-1249.

3. Watanabe i. Matsumura H, Atsuta M. Effect cf twc metalprimers en adhesive bonding with type IV goid alloys. J Prcs-thet Dent 1995;73:299-303.

4. Zachrisson BU, Buyukyilmaz T. Recent Advances in Bondingto Geld, Amalgam, snû Porcelain. J Clin Orthcd 1993:27:661-675.

238 The Journal of Adhesive Dentistry