inside dentistry handpiece and diamond selection dr alan atals oct11 vol7 iss9

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October 2011 Volume 7 Issue 9Published by AEGIS Communications

Handpiece and Diamond Selection

Careful consideration of this component of the armamentarium iscritical for optimal results in restorative dentistry

By Alan M Atlas DMD

The development of the dental handpiece is considered one of the most important advancements indentistry Since 1868 when Green and a few years later Morrison in 1871 introduced the air-

driven handpiece that transformed the dental profession technology especially over the past 50

years continues to improve the speed and efficiency of tooth preparation and increase handpiece

performance and longevity1

The air-turbine high-speed handpiece continues to be the most popular type of high-speed

handpiece due to its reasonable cost for purchase and repair ability to rapidly remove tooth

structure excellent ergonomic weight and size and reduced risk of pulpal damage when used

properly2 The high-speed electric handpiece was introduced as an alternative option to the air-

driven device but has been unable to achieve a significant market share in America3 These

handpieces are considered more costly to purchase and repair have larger contra-angle heads

and are heavier in weight which may cause problems with ergonomics and reduced visual access

Advantages of the electric version are reported to be improved precision torque and cutting

efficiency

The goal for any operative dental procedure is to achieve conservative atraumatic and precise

preparations for optimal long-term outcomes Kenyon and colleagues evaluated the quality of dental

preparations performed by dental students comparing the air-driven and the electric handpiece The

results indicated that differences in preparation and refinement scores between the two handpieces

was not statistically significant2

Clinicians have the opportunity to perform precision dentistry using state-of-the-art armamentarium

Recent advancements in handpiece technology now offer an air-powered adaptive air and electric

control in one system (eg Midwest reg Stylustrade ATC DENTSPLY Professional

wwwprofessionaldentsplycom) enabling the power and efficiency of electric without the added

size and weight This type of handpiece can deliver constant torque at high speeds enabling

superior preparation

With the advent of contemporary dental adhesive technology the proper selection of a dental

handpiece and accompanying diamond or bur selection becomes even more critical for optimal

outcomes The preparation of tooth structure for removal of a carious lesion or defect creates the

substrate for the final restoration During this preparation enamel and dentin surface characteristics

that make up the cavity walls and margins are affected differently depending on the size and shapeof the instrumentation

In 1962 Kasloff et al4 showed that upon preparation with different handpieces fewer enamel cracks

and microfractures occurred when diamond points were used instead of carbide burs Another

study demonstrated that the degree of enamel damage is influenced by the diamond grit size and

type of bur5 Fine-grit and superfine-grit diamond burs produce less marginal enamel cracks than

regular-grid diamond burs and six-bladed carbide burs as well as improve the marginal adaptation

of the adhesively placed composite resin to the cavity wall6 A smooth cavosurface and proximal

margin will reduce enamel irregularities and cracking resulting from the polymerization stress of

light-curing and finishing and allow for a more intimate contact between enamel and composite if

the bonding agent is carefully placed without excess The net clinical outcome will be enhanced

marginal integrity of the restoration and improved long-term outcomes

A diversity of scientific opinion has evolved about the effect of diamonds on bond strengths to

dentin depending on the strategy employed for adhesion The result of dentin preparation is a

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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smear layer consisting of ground-up dentin bacteria collagen and hydroxyapatite not tightly

attached to the dentin substrate This layer is considered a barrier to resin-monomer infiltration and

must be treated before resin is applied The two approaches used today are phosphoric acid in a

total-etch or an etch-and-rinse system which completely removes the smear layer or the self-etchsystem that uses acidic monomers to simultaneously demineralize and infiltrate the smear layer

incorporating it within the resinndashdentin bond Ermis et al7 concluded that for the etch-and-rinse and

strong highly acidic self-etch adhesive systems the bonding effectiveness is unaffected by

diamond or bur type while for ultra-mild less-acidic self-etch adhesives bond strengths can be

significantly improved by finishing the cavity preparation with fine-grit diamond burs Marques et al8

had a similar conclusion in their study stating that a course-cut carbide bur should be avoided prior

to using a mild self-etch adhesive while a fine-cut carbide bur provided the best bond strength

Studies910 have demonstrated that rounded internal line angles produced by appropriately shaped

diamonds lead to a reduction of stress along the adhesive interface between the tooth and

composite restoration In addition tooth preparations for indirect restorations refined with finishing

burs or super-fine diamonds may favor the placement of restorations with the smallest marginal

discrepancies regardless of the type of cement used11 This is best achieved with specifically

shaped modified shoulder and feather-edge diamond burs (eg 836 KR F 845 KR F 847 KR F

and 888 EF Midwest Diamonds DENTSPLY Professional) with fine and superfine grits used on

enamel and dentin rather than carbides as well as an innovative handpiece that allows precisepreparation as described in the following case study

Case Study

This case study will describe the placement of a direct posterior composite restoration using a state-

of-the-art dental handpiece specifically shaped and grit diamonds a sectional matrix system for

proper contacts and exceptional resin composite materials placed incrementally using careful and

controlled placement to minimize finishing of the restoration

The patient presented with a defective composite restoration due to recurrent caries at the distalndash

gingival margin (Figure 1) After rubber-dam placement to control potential contamination of the

operative field (Figure 2) initial preparation commenced using the Midwest reg Stylustrade ATC dental

handpiece (Figure 3) The unique features of this handpiece are the speed-sensing intelligence that

uses a sensor to maintain speed and torque while under the load of tooth preparation In addition

this handpiece offers superior turbine suspension to deliver exceptional control precision and

accuracy

The rationale for diamond selection has been described above (Midwest Diamonds DENTSPLY

Professional) The 836 KR medium-grit diamond created a conservative rounded internal line-angle

cavity shape and dentin preparation was finished with the 836 KR extrafine diamond for an ideal

substrate surface for the adhesive system selected (Figure 4) The enamel cavosurface margin and

interproximal walls were finished with the 888 extrafine diamond to create smooth aprismatic

enamel surfaces for optimal placement of the restoration (Figure 5) The final preparation had the

correct finish lines for the best adaptation of the sectional matrix adhesive bonding agent and

composite resin material (Figure 6)

The V3 sectional matrix band and separation ring (Triodent wwwtriodentcom) was placed to

achieve the correct convex contours for proper tooth contacts (Figure 7) Prior to the self-etch

bonding system application a selective enamel etch was incorporated in the technique to maximize

the bond strength to the enamel cavosurface margins only (Figure 8)12 The viscous 37

phosphoric etch was not applied to the gingival box enamel if it were present to avoid placement

on dentin when using a self-etch adhesive system The etchant was placed for 15 seconds rinsed

well for 10 seconds and the tooth adequately dried The self-etch adhesive system used Xeno IV reg

(DENTSPLY Caulk wwwcaulkcom) was agitated on dentin carefully applied to the enamel

surfaces and the excess was picked up using a microbrush (Figure 9) It was then air-dried and

light-cured for 10 seconds using an LED curing light (Smartlite reg Max DENTSPLY Caulk)

The composite resin was placed incrementally in an open-sandwich technique where all layers of

composite would be exposed to the oral environment when the matrix band was removed The first

horizontal increment of resin composite was Surefil reg SDRtrade flow (DENTSPLY Caulk) (Figure 10)

This unique composite features low viscosity self-leveling low shrinkage and low contraction-

stress properties that enable exceptional marginal adaptation at gingival box areas13 The first

vertical increment of a micro-nanohybrid composite (Esthet-X HD reg DENTSPLY Caulk) was placed

in a technique described as controlled placement14 where the material was positioned only against

the walls of the entire cavity leaving space internally to allow the composite to flow and obtain

maximum adaptation with minimal strain or stress as it underwent light polymerization and

transformed from monomer paste to a rigid polymer (Figure 11)15 The last vertical increment was

the most confined and stressful to the cavity but it was placed against the first horizontal and

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14





vertical composite increments and did not touch any tooth surface (Figure 12) The separation ring

was removed from the tooth and the matrix band was opened to allow for inspection of margins and

additional light-curing for complete conversion and polymerization (Figure 13) Due to the controlled

placement of the composite resin the final restoration was finished minimally with finishing

diamonds preserving sound healthy enamel and polished well with a one-step polishing system

(POGO reg Diamond Micro Polishing System DENTSPLY Caulk) (Figure 14)

Conclusion

Precision dentistry using a state-of-the-art dental handpiece specifically shaped and grit diamonds

sectional matrix systems and carefully placed exceptional bonding agents and resin composite

materials will ensure extraordinary long-term outcomes

References1 Choi C Driscoll CF Romberg E Comparison of cutting efficiencies between electric and air-

turbine dental handpieces J Prosthet Dent 2010103(2)101-107

2 Kenyon BJ van Zyl I Louie KG Comparison of cavity preparation quality using an electric motor

handpiece and an air turbine dental handpiece J Am Dent Assoc 2005136(8)1101-1105

3 Christensen GJ Are electric handpieces an improvement J Am Dent Assoc 2002133(10)1433-

1434

4 Kasloff Z Swartz ML Phillips RW An in vitro method for demonstrating the effects of various

cutting instruments on tooth structure J Prosthet Dent 196212(6)1166-1175

5 Xu HHK Kelly JK Jahanmir S et al Enamel subsurface damage due to tooth preparation with

diamonds J Dent Res 199776(10)1698-1708

6 Nishimura K Ikeda M Yoshikowa T et al Effect of various grit burs on marginal integrity of resin

composite restorations J Med Dent Sci 200552(1)9-15

7 Ermis RB De Munck J Van Meerbeek B et al Bond strength of self-etch adhesives to dentin

prepared with three different diamond burs Dent Mater 200824(7)978-985

8 Marques MM Kenshima S Muench A et al Effect of c-factor and dentin preparation methods in

bond strength of a mild self-etch adhesive Oper Dent 200934(4)452-459

9 Hubsch P Middleton J Knox J The influence of cavity shape on stresses in composite dental

restorations a finite study Comput Methods Biomech Biomed Engin 20025(5)343-349

10 Kinomoto Y Torii M Takeshige F et al Polymerization contraction stresses of resin-based

composite restorations within beveled cavity preparations of class I restorations Am J Den t

200316(2)139-143

11 Ayad MF Effects of tooth preparation burs and luting cement types on the marginal fit of

extracoronal restorations J Prosthodont 200918(2)145-151

12 Van Meerbeek B Yoshihara K Yoshida Y et al State of the art self-etch adhesivesDent Mater 201127(1)17-28

13 Ilie N Hickel R Investigation on a methacrylate- based flowable composite based on the SDRtrade

technology Dent Mater 201127(4)348-355

14 Atlas AM The controlled placement and delayed polymerization technique for the direct class 2

posterior composite restoration Compend Contin Educ Dent 200526(11)812-818

15 Ferracane JL Buonocore Lecture Placing dental composites-a stressful experienceOper Dent

200833(3)247-257

About t he Au thor

Alan M Atlas DMD

Clinical Associate Professor

University of Pennsylvania School of Dental Medicine

Philadelphia Pennsylvania

Private Practice


Share this

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smear layer consisting of ground-up dentin bacteria collagen and hydroxyapatite not tightly

attached to the dentin substrate This layer is considered a barrier to resin-monomer infiltration and

must be treated before resin is applied The two approaches used today are phosphoric acid in a

total-etch or an etch-and-rinse system which completely removes the smear layer or the self-etchsystem that uses acidic monomers to simultaneously demineralize and infiltrate the smear layer

incorporating it within the resinndashdentin bond Ermis et al7 concluded that for the etch-and-rinse and

strong highly acidic self-etch adhesive systems the bonding effectiveness is unaffected by

diamond or bur type while for ultra-mild less-acidic self-etch adhesives bond strengths can be

significantly improved by finishing the cavity preparation with fine-grit diamond burs Marques et al8

had a similar conclusion in their study stating that a course-cut carbide bur should be avoided prior

to using a mild self-etch adhesive while a fine-cut carbide bur provided the best bond strength

Studies910 have demonstrated that rounded internal line angles produced by appropriately shaped

diamonds lead to a reduction of stress along the adhesive interface between the tooth and

composite restoration In addition tooth preparations for indirect restorations refined with finishing

burs or super-fine diamonds may favor the placement of restorations with the smallest marginal

discrepancies regardless of the type of cement used11 This is best achieved with specifically

shaped modified shoulder and feather-edge diamond burs (eg 836 KR F 845 KR F 847 KR F

and 888 EF Midwest Diamonds DENTSPLY Professional) with fine and superfine grits used on

enamel and dentin rather than carbides as well as an innovative handpiece that allows precisepreparation as described in the following case study

Case Study

This case study will describe the placement of a direct posterior composite restoration using a state-

of-the-art dental handpiece specifically shaped and grit diamonds a sectional matrix system for

proper contacts and exceptional resin composite materials placed incrementally using careful and

controlled placement to minimize finishing of the restoration

The patient presented with a defective composite restoration due to recurrent caries at the distalndash

gingival margin (Figure 1) After rubber-dam placement to control potential contamination of the

operative field (Figure 2) initial preparation commenced using the Midwest reg Stylustrade ATC dental

handpiece (Figure 3) The unique features of this handpiece are the speed-sensing intelligence that

uses a sensor to maintain speed and torque while under the load of tooth preparation In addition

this handpiece offers superior turbine suspension to deliver exceptional control precision and

accuracy

The rationale for diamond selection has been described above (Midwest Diamonds DENTSPLY

Professional) The 836 KR medium-grit diamond created a conservative rounded internal line-angle

cavity shape and dentin preparation was finished with the 836 KR extrafine diamond for an ideal

substrate surface for the adhesive system selected (Figure 4) The enamel cavosurface margin and

interproximal walls were finished with the 888 extrafine diamond to create smooth aprismatic

enamel surfaces for optimal placement of the restoration (Figure 5) The final preparation had the

correct finish lines for the best adaptation of the sectional matrix adhesive bonding agent and

composite resin material (Figure 6)

The V3 sectional matrix band and separation ring (Triodent wwwtriodentcom) was placed to

achieve the correct convex contours for proper tooth contacts (Figure 7) Prior to the self-etch

bonding system application a selective enamel etch was incorporated in the technique to maximize

the bond strength to the enamel cavosurface margins only (Figure 8)12 The viscous 37

phosphoric etch was not applied to the gingival box enamel if it were present to avoid placement

on dentin when using a self-etch adhesive system The etchant was placed for 15 seconds rinsed

well for 10 seconds and the tooth adequately dried The self-etch adhesive system used Xeno IV reg

(DENTSPLY Caulk wwwcaulkcom) was agitated on dentin carefully applied to the enamel

surfaces and the excess was picked up using a microbrush (Figure 9) It was then air-dried and

light-cured for 10 seconds using an LED curing light (Smartlite reg Max DENTSPLY Caulk)

The composite resin was placed incrementally in an open-sandwich technique where all layers of

composite would be exposed to the oral environment when the matrix band was removed The first

horizontal increment of resin composite was Surefil reg SDRtrade flow (DENTSPLY Caulk) (Figure 10)

This unique composite features low viscosity self-leveling low shrinkage and low contraction-

stress properties that enable exceptional marginal adaptation at gingival box areas13 The first

vertical increment of a micro-nanohybrid composite (Esthet-X HD reg DENTSPLY Caulk) was placed

in a technique described as controlled placement14 where the material was positioned only against

the walls of the entire cavity leaving space internally to allow the composite to flow and obtain

maximum adaptation with minimal strain or stress as it underwent light polymerization and

transformed from monomer paste to a rigid polymer (Figure 11)15 The last vertical increment was

the most confined and stressful to the cavity but it was placed against the first horizontal and

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14











Conclusion









1434















200316(2)139-143









200833(3)247-257

About t he Au thor

Alan M Atlas DMD




Private Practice


Share this












Conclusion









1434















200316(2)139-143









200833(3)247-257

About t he Au thor

Alan M Atlas DMD




Private Practice


Share this


inside dentistry handpiece and diamond selection dr alan atals oct11 vol7 iss9

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