Effects of Preventive Procedures on Dental Restorations

Many patients receive preventive dental hygiene procedures twice a year and periodontal maintenance procedures up to four times per year. The instrumentation technique and products selected by the dental hygienist can be beneficial or detrimental to the patient’s dental restorations. Therefore, it is imperative to identify the restorative materials that are present before starting treatment. Restorations can be identified through reviewing radiographs, tactile detection and applying air to the surface of the restoration. Often times, a black line of metal may be apparent when an explorer is used on the restoration. Esthetic restorations may also reveal a dry, chalky appearance when air is applied.¹

Preventive and maintenance procedures are often performed using a combination of hand and ultrasonic instrumentation, which is followed by polishing. It is important to use the combination that will be most effective for deposit removal, while causing the least amount of damage to restoration and tooth structure. There is conflicting evidence regarding the effect of scaling with hand instruments versus ultrasonic instrumentation and the amount of tooth structure that is lost in each case. Some studies report that scaling with hand instruments produces greater loss of tooth structure.^2,23,24 However, other studies indicate that there is not a significant difference in the amount of tooth structure lost when comparing hand and ultrasonic instrumentation.^25,26

Instrumentation with ultrasonic scalers and hand instruments has the potential to damage composite restorations (hybrid and microfilled), glass ionomers, laminate veneers and titanium implant abutments. When using ultrasonic instrumentation, the clinician should always establish proper water flow to prevent overheating, use the appropriate power level that is needed for deposit removal, and maintain correct adaptation of the side of the tip.²¹ Ultrasonics have the potential to alter the margins of amalgam restorations and fracture porcelain. In order to avoid damaging the restoration, the tips of scalers should never be directed into the junction where the enamel and restorative material meet.³

Due to the potential for damage to titanium implant abutments, clinicians can use specialized instruments while scaling around them. There are plastic tips to cover inserts when using an ultrasonic scaler (Figure 7). Tips are available for both magnetostrictive and piezoelectric models. There are also titanium and plastic tipped hand instruments that are best for deposit removal around implants.

Figure 7. Plastic tip for safe ultrasonic instrumentation near implants.

Figure 7. Plastic tip for safe ultrasonic instrumentation near implants.

Retrieved from Dentsply Sirona

For clinicians who prefer to use air-powder polishing systems, some studies show that air polishing may be more effective at plaque and stain removal than polishing with rotating cups and abrasive pastes.^28,29 In comparison, Chowdhary and Mohan found that polishing with a rubber cup was more effective than air polishing for smoothing and debris removal.³³ Air polishing is also effective when preparing teeth for sealants. However, air polishing should be avoided once sealants have been placed.³¹ Care should also be taken when using air polishers near restorations. An in vitro study using bovine mandibular incisors found that air-powder polishing devices created larger marginal gaps in Class V restorations than when prophylaxis was performed with a rubber cup and pumice powder.³⁰

Traditionally, sodium bicarbonate powders have been used for air-powder polishing devices.³¹ However, there are additional powders available for use with air polishers. These include glycine, calcium sodium phosphosilicate, calcium carbonate and aluminum trihyrdoxide powders.^19,31 These new powders have the added benefit of containing very little or no sodium, which is beneficial for patients on sodium-restricted diets.³¹ Clinicians should be familiar with the properties of each agent and understand the manufacturers’ respective recommendations.³¹ For example, due to the surface alterations that were observed visually and with a Scanning Electron Microscope, aluminum trihydroxide powder should be avoided on resin composites, resin-modified composites and around the margins of cemented restorations.⁴ In general, dental clinicians should avoid the use of air polishers on composite restorations.¹ However, glycine-based powders were found to create fewer defects on restorative material and tooth structures³¹ and may be preferable for that reason.

Fluoride application is beneficial for preventing recurrent decay near dental restorations. According to Artopoulou et al., 1.1% sodium fluoride (NaF) is the preferable choice for esthetic restorations. Sodium fluoride has been shown to cause less stain and deterioration of porcelain surfaces than 0.4% stannous fluoride (SnF2).⁵ Dental hygienists should also avoid the use of acidulated phosphate fluoride, which may cause alteration of the filler particles and discoloration of the resin. If fluoride mouthrinses are recommended for home care, avoid suggesting rinses that contain alcohol, which acts as a solvent for the BIS-GMA resin. This results in softening the material, which can increase roughness and stain.¹

The use of CAD/CAM (computer-aided design/computer-aided manufacturing) restorations within dental practices has increased and dental clinicians will need to be familiar with their characteristics in order to properly maintain them.⁶ Some materials, such as e.max CAD lithium disilicate ceramic (Figure 8), have good abrasion resistance, but prophylactic pastes produced a reduction in translucency.⁷ In a study comparing the effects of prophylaxis on surface gloss and roughness of CAD/CAM composite resin and ceramic blocks (intended for indirect restorations), it was found that surface changes from using course paste were not improved by subsequent polishing with fine paste.³⁴ This suggests the importance of using the finest paste possible to perform the procedure. In order to keep the restoration looking new and as natural as possible, it is important to follow manufacturers’ recommendations regarding the appropriate product to use for maintaining the restoration.¹

Figure 8. These radiographs show crowns made of lithium disilicate (often called e.max). They appear slightly radiopaque radiographically.

Figure 8. These radiographs show crowns made of lithium disilicate (often called e.max). They appear slightly radiopaque radiographically.

Images courtesy of Dr. Brian Goodacre, Loma Linda, CA.