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Healthcare Trust and ICDR are playing a vital role in continuing education. In near future we plan to bring you a course on Efficient Begg Technique, with this technique as we will teach you will be able to get results almost as good as straight wire. To get more information on this e mail to begg@healthmantra.com

In this issue we bring you a lot of variety. You will find here information on

Fifth generation bonding
Restoration of endodontic teeth
About whitening agents
Caries disclosing agents
Composite polishers
LED curing lights

To send your views or suggest topics for future send e mail to ypb@healthmantra.com

Fifth-Generation Bonding Agents

Dentin bonding agents (DBAs) that don't require a separate phosphoric etchant acid are called "self- etching primer" products. They bond to dentin and cut (i.e. prepared) enamel by etching the tooth with an acid that is already in the bonding agent. In other words, no separate phosphoric acid etching is necessary with them. Self-etching primer DBAs come as either two bottles (a self-etching primer, followed by a separate adhesive) or one (etchant, primer, and adhesive all-in-one). Examples of each type are given in the table below

Two-Bottle Products	One-Bottle Products
Clearfil SE bond (Kuraray) Clearfil Liner Bond 2V (Kuraray)	Prompt L-Pop (3M ESPE) One-Up Bond F (Tokuyama/J. Morita) Touch & Bond (Parkel)

Perhaps the most recent development in bonding has been the addition of self-etching primers to the fifth- generation bonding agents. Fifth-generation DBAs, also known as "one-bottle" or "one-component" DBAs, have been available since the mid-1990s and include such products as Single Bond (3M ESPE), OptiBond Solo Plus (SDS/Kerr), PQ1 (Ultradent), Excite (Ivoclar Vivadent). Their manufacturers don't want to be left behind now that self-etching primers have become popular, so they have incorporated these into their product lines. Until very recently, the fifth-generation DBAs consisted of a single bottle or syringe that contained both the primer and the adhesive. The tooth structure needed to be treated with phosphoric acid before they were applied. Now, in response to the latest self-etching primer products, the manufacturers of some of the fifth- generation DBAs are selling them with self-etching primers that are used in place of the phosphoric acid. Why do this? Well, the manufacturers claim that using a self-etching primer reduces post-treatment sensitivity and shortens the clinical procedure. In addition, you no longer have to be concerned about how moist the tooth should be at the time of application. Two examples of fifth-generation DBAs now available with self-etching primers are One-Step Plus with Tyrian SPE from Bisco and OptiBond Solo Plus with Self- Etch Primer from SDS/Kerr. If you use One-Step Plus or OptiBond Solo Plus and want to reduce the possibility of post-treatment sensitivity, you may want to consider trying a self-ecthing primer with it. Please note, though, that not all fifth-generation DBAs come with self-etching primers; the only ones currently available are the SDS/Kerr and Bisco products.

Through the technology of self-etching adhesives it is now possible to avoid some of the problems that have been associated with the total-etch technique. Post operative sensitivity can be eliminated using the selfetch technique which is even significantly less technique-sensitive than total-etch.

One-Up Bond F changes colour giving the clinician a clear
indication of when the bonding agent A & B have mixed.
(Material turns from yellow to pink upon mixing, and the pink
colour will disappear upon light curing. The pink colour gives
an easy to read guide to full tooth coverage.

DO ENDODONTICALLY-TREATED TEETH REALLY BENEFIT FROM CROWN PLACEMENT?

Relationship between crown placement and the survival of endodontically treated teeth. Aquilino SA, Caplan DJ. J Prosthet Dent 2002;87:256-263.

Traditionally, it has been accepted that the best treatment for a posterior, endodontically-treated tooth is some form of coronal coverage. This may take the form of a gold, ceramic, resin composite, or amalgam restoration that covers the occlusal aspect of the tooth to prevent it from fracture. The purpose of this retrospective study was to evaluate the hypothesis that crown placement improves the long-term survivability of endodontically-treated teeth. The researchers used a dental school database to identify 280 patients (400 teeth) that had received endodontic during a two-year period. Patient records, radiographs, and a computer database were used to select from this number those who met the inclusion criteria of the study. Kaplan-Meier survival estimates were then generated for those 203 teeth. Results indicated that endodontically- treated teeth that had not received a crown were lost at a rate six times greater than those that had. The authors concluded there was a strong association between placement of a crown and survival of an endodontically-treated teeth.

Quite a number of previously published articles and scientific papers have voiced the opinion that endodontically-treated posterior teeth (as well as anterior teeth with loss of significant coronal tooth structure) should receive crowns to protect them from fracture and extend their longevity. At least one study has shown that crowned endodontically-treated teeth survive longer than those that were not crowned. As the authors of the current study indicated, crowns are not the only viable option to protect teeth following obturation. Cuspal coverage may also be provided by complex amalgams and by gold, ceramic, and resin composite onlays. Unfortunately, although one would expect that these treatments would function for this purpose at least as well as full coronal coverage, no reports exist in the literature to support this contention. Regardless of the specific treatment employed, the evidence does seem to indicate that obturated teeth benefit from restorative coverage of their fracture-prone occlusal surfaces.

TOOTH WHITENING AGENTS: WHAT A PAIN!

Sensitivity and tooth whitening agents. Pohjola RM, Browning WD, Hackman ST, Myers ML, Downey MC. J Esthet Restor Dent 2002;14:85-91.

One of the common side effects of bleaching vital teeth is tooth and gingival sensitivity to changes. Several new bleaching products have been marketed to address this problem. This study evaluated three commercially-available products to identify their incidence of sensitivity (involving teeth and soft tissues) and efficacy of whitening. Eighteen patients were divided into three groups of six each. Each of thegroups was treated for two weeks with one of the following whitening agents: NiteWhite Excel 2Z (Discus Dental), fx (Challenge Products), and Rembrandt Xtra-Comfort (Den-Mat). Patients kept a daily diary to record sensitivity and the first day they noticed a whitening effect. Shade change and tooth sensitivity were evaluated at recall appointments at 1 week, 2 weeks, and 4 weeks. Results indicated that the two products marketed as zero-sensitivity bleaches (NiteWhite Excel 2Z and Rembrandt Xtra-Comfort) produced no teeth sensitivity and were significantly different in this regard from fx. All produced a statistically similar degree of soft tissue sensitivity. All three were found to be effective whiteners, producing an average shade guide change of 8. The authors concluded that of the three products, none was sensitivity free, but NiteWhite Excel 2Z and Rembrandt Xtra-Comfort (the zero sensitivity products) did not produce thermal sensitivity. All produced a similar change in shade tab value.

A very common side effect of vital tooth bleaching is transient sensitivity of the teeth and/or soft tissues. Fortunately, the sensitivity is dose-related and transient. Regardless, it is frustrating for patients and enough of an annoyance to dissuade some from finishing treatment. Recently, manufacturers have added potassium nitrate an/or fluoride in an attempt to reduce sensitivity. This study indicates that these products are at least effective at reducing the incidence of thermally-related tooth sensitivity, while retaining their effectiveness at tooth whitening. Practitioners should note that they do not reduce soft tissue sensitivity, so patients should be advised that they may experience transient gingival, tongue, or throat sensitivity with these products.

HOW ABOUT THOSE CARIES DISCLOSING PRODUCTS?

Effect of caries disclosing agents on bond strengths of total-etch and self-etching primer dentin bonding systems to resin composite. Kazemi RB, Meiers JC, Peppers K. Oper Dent 2002;27:238-242.

This study evaluated the effect of two commercially-available caries detection solutions on the bond strength of three bonding products to resin composite. Extracted human molars were sectioned to produce 108 flat dentin surfaces. Thirty-six surfaces were then either left untreated (control) or treated with one of two caries disclosing solutions (Snoop, Pulpdent or Seek, Ultradent). The 36 specimens of each type of treatment were then treated with one of three bonding agents: Prime & Bond NT (a partially filled, total-etch product from Dentsply/Caulk), Clearfil SE Bond (a self-etching primer product from Kuraray), or Prompt L-Pop (a self-etching primer, all-in- one product from Parkell). Tetric Ceram (Ivoclar Vivadent) resin composite was then bonded to the dentin surfaces. The specimens were stored for 24 hours, thermocycled, and tested for shear bond strength. Results indicated that neither of the two caries disclosing solutions significantly affected the bond strength of the bonding products.

Caries detection solutions have been been used by clinicians to distinguish between affected and infected dentin. Affected dentin is the dentin that is adjacent to a carious lesion and is not contaminated by bacteria. While it may be softer than normal dentin, it should be retained because it has the potential for remineralization. Infected dentin, on the other hand, contains bacteria and should be removed during preparation. Several commercial products are now available for distinguishing between the two, such as Caries Detector, Snoop, Seek, and To Dye For. DIS published a synopsis of these products in DIS 63-07. This study evaluated how these products affect the shear bond strengths of some of the newest types of bonding agents. The results of the study should give clinicians who routinely use caries detection solution some reassurance that, for at least the tested bonding agents, no adverse effects occur. It is important to note, however, that the caries detection solutions and bonding agents in this study were tested using sound, intact dentin and not carious dentin as would be the case intraorally. Results may differ when caries-affected dentin is involved. Interestingly, although the purpose of this study was not to compare the bond strengths of the three dentin bonding products, Prompt L-Pop did not perform as well as CLearfil SE Bond and Prime & Bond NT.

PoGo One Step Diamond Micro-Polishers

PoGo One Step Diamond Micro-Polishers from Dentsply/Caulk are used for polishing resin composite and compomer restorative materials. Each is a diamond-impregnated, urethane dimethacrylate disc mounted on a plastic, latch-type, slow-speed handpiece mandrel. The single-use discs are used with increasing light pressure to purportedly produce a highly polished surface. A PoGo Starter Kit contains 40 discs, written instructions, and a laminated instruction card.

NRG� LED Curing Light

The NRG� LED Curing Light uses focused Light Emitting Diode (LED) technology to polymerize visible-light-activated materials having camphoroquinone as their photoinitiator. Dentsply/Caulk claims that the NRG� Light is capable of polymerizing a 2-mm-thick layer of most of its visible light-cured materials in 10 seconds. This unit, like other first- generation LED curing lights, uses gallium nitride semiconductors to produce a narrow spectral range that is close to the absorption spectrum of camphorquinone (i.e., 450 to 490 nm). Due to the combination of this more specific spectral range and the LED's superior energy conversion rate compared to halogen lamps, the NRG� LED Curing Light is purported to generate sufficient intensity for polymerization using rechargeable batteries rather than line voltage. This allows the NRG� LED Curing Light to be portable and lightweight, and it eliminates the need for restrictive cords. A fully-charged battery is reported to typically provide 250 ten-second exposures (i.e., 40 minutes) without recharging. A fully depleted battery requires overnight recharging. The NRG� LED Curing Light, in contrast to the wand design of most other available LED curing lights, uses the more familiar gun-shaped design of conventional halogen curing lights. The controls are located on the handpiece and consist of an on/off button and an activation button. There is no timer selection; only 10-second exposures are available. Longer exposures are accomplished by depressing the activation button every 10 seconds. The NRG� LED Curing Light is shipped with a 9-mm-diameter, non- autoclavable light guide containing 7 LEDs. Optional light guides include a 3-mm "tacking probe" for tacking indirect resin restorations, and a 3-mm "transillumination probe." Dentsply/Caulk recommends barrier protection of the light guide or disinfection. The NRG� LED Curing Light is 9 inches long and 4� inches deep and weighs 16 ounces. The charging unit is only available in 120V at this time.

Manufacturer:

Dentsply/Caulk www.caulk.com

PROs

+ Portable and light weight.

+ Ergonomic, with familiar gun- shaped design.

+ Adequately polymerizes hybrid resin composite in 35 seconds.

+ Very quiet.

CONs

- Did not cure Dentsply/Caulk resin composite in 10 seconds as advertised.

- Required 63 seconds to adequately cure microfill.

- Didn't maintain output as battery discharged.

- Activation button is inconveniently located.

- More expensive than halogen lights.

ADVANTAGES:

+ Offers the conveniences of portability and light weight.

+ Is ergonomic and has a familiar gun-shaped design.

+ Adequately polymerizes hybrid resin composite in 35 seconds.

+ Curing tip swivels 360 degrees to facilitate intraoral access.

+ Instructions are clear and easy to understand.

+ Very quiet.

+ Requires little counter space for storage.

DISADVANTAGES:

- Did not cure Dentsply/Caulk resin composite in 10 seconds as advertised.

- Required 63 seconds to adequately cure microfill resin composite.

- Required more time than the control halogen light unit to adequately polymerize all resin composites tested.

- Activation button is not easy to use because of its inconvenient location.

- Did not maintain initial output throughout battery discharge.

- Not provided with built-in radiometer.

- Rechargeable battery is not replaceable without returning the unit to manufacturer.

- More expensive than most halogen curing lights.

- Curing tip becomes warm with repeated use.

- Handpiece is easy to incorrectly place in charging base.

- Has only one exposure time setting (10 seconds).

- Curing tips are not autoclavable.

- Different types of disinfectants are recommended for curing tip and handpiece.

SUMMARY AND CONCLUSIONS:

The NRG� LED Curing Light is a lightweight, compact curing light that uses the light emitting diode (LED) technology. Clinical evaluators appreciated its portability, convenience, and gun-shaped design, however the activation button was not placed in the proper position for easy use. The light is advertised by Caulk/Dentsply as being able to polymerize resin composites in 10 seconds. DIS testing could not substantiate this claim even when a Dentsply/Caulk resin composite was used. Using the same resin composites as in past evaluations, the NRG� LED Curing Light adequately polymerized the hybrid resin composite in a timely manner, but not the microfill resin composite. However, previous DIS testing has found that most standard (i.e., average-intensity) halogen lights also inadequately polymerize microfill resin composites unless used for 60 seconds. Only high- intensity halogen lights (i.e., with an output of >1000 mW/cm2) can predictably polymerize microfills in 40 seconds or less. When using an average-intensity halogen light (i.e., 300 to 600 mW/cm2) to cure a 2-mm-thick resin composite, 40 seconds are required to adequately polymerize a hybrid resin composite and 60 seconds for a microfill. DIS testing found that the NRG� LED Curing Light required approximately the same amount of time (35 seconds and 63 seconds) to polymerize the same materials. Because the unit's LEDs are at the end of the curing tip, the tip is not autoclavable. Adding to this problem is the fact that two different classes of disinfectants are recommended for the curing tip and plastic handpiece. Despite its numerous disadvantages, the clinical evaluators rated the light as "Good" to "Excellent," primarily because of its portability and light weight. Unfortunately, the advantages of portability and ease of use do not outweigh the inability of the light to meet advertising claims.