Which Dental Bur Performs Best for Enamel Cutting? A Research Comparison of Fissure, Diamond and Round Burs

Selecting the right dental bur is not simply a matter of choosing a familiar shape. Bur geometry can influence cutting force, heat generation, surface quality and the level of control achieved during enamel preparation.

A fissure bur, diamond bur and round bur may all be used during dental procedures, but they do not interact with enamel in the same way. Each design has a different cutting mechanism. This affects how efficiently the instrument penetrates the enamel, how much heat is generated and the quality of the resulting surface.

A 2023 in-vitro study by Zhao et al. compared the performance of these three dental burs during enamel cutting. The findings provide a useful framework for understanding why one bur may perform well for initial penetration while another may be more suitable for lateral shaping and contouring.

The main conclusion is clear: there is no universal best dental bur for every procedure. The most appropriate bur depends on the clinical objective.

Why Dental Bur Selection Matters

Enamel is the highly mineralised outer layer of the tooth. Its hardness helps protect the underlying tooth structure, but it also presents challenges during dental preparation.

When a rotating bur contacts enamel, it generates mechanical force and friction. Excessive force may affect cutting control and contribute to unnecessary structural damage. Friction can also increase the cutting temperature.

For dentists, this means that bur selection is closely related to precision and efficiency. A suitable bur should remove the intended tooth structure while limiting excessive force, unnecessary heat and irregular surface damage.

Zhao et al. designed their study to examine these differences more closely. The researchers compared three commonly recognised bur designs:

• fissure bur

• diamond bur

• round bur

The study evaluated how these burs performed during two types of enamel cutting: drilling and lateral cutting.

Drilling vs Lateral Enamel Cutting

The distinction between drilling and lateral cutting is important when interpreting the research findings.

Drilling refers to advancing the bur directly into the enamel to create an opening. During this movement, the tip of the bur plays an important role.

Lateral enamel cutting refers to moving the bur sideways across the enamel surface to shape or enlarge an area. The researchers used the engineering term “milling” to describe this action.

In a clinical context, lateral cutting may be relevant when shaping preparation walls, contouring a surface or creating a flatter prepared area. The side of the bur becomes more important than the tip.

A dental bur that performs well during drilling may not necessarily provide the best results during lateral shaping. This is one of the most useful lessons from the study.

How the Study Was Conducted

The researchers established an experimental system to evaluate bur performance during enamel cutting.

Each bur had a diameter of 1.4 mm. The drilling tests were conducted at feed rates of 10, 30 and 50 mm per minute, while the lateral-cutting tests were performed at a feed rate of 10 mm per minute.

The study evaluated enamel cutting across three tooth-surface categories:

• occlusal surface

• buccal or lingual surface 

• mesial or distal surface

The researchers measured several factors:

1. drilling thrust force

2. lateral-cutting force

3. drilling temperature

4. lateral-cutting temperature

5. drilling quality

6. drilling precision 

7. surface quality after lateral cutting

The purpose was not simply to identify a winning bur. The researchers wanted to understand how bur geometry affects the cutting mechanism.

Which Bur Required the Lowest Drilling Force?

During drilling, the round bur generated the smallest thrust force. The fissure bur generated the highest drilling force, while the diamond bur and round bur produced lower thrust forces.

The study explained this result through the shape of the round bur. Its curved cutting edges remove material in a way that partially offsets the axial force acting on the enamel.

This finding suggests that the round bur has a practical mechanical advantage when the main objective is initial penetration with lower drilling force.

However, lower drilling force does not mean that the round bur is automatically the best choice for every stage of enamel preparation. Its performance changed when the cutting direction changed.

Which Bur Performed Best During Lateral Cutting?

During lateral cutting, the pattern was different.

The round bur generated the highest cutting force. Its average lateral-cutting force was approximately 14.93% higher than that of the fissure bur and 15.72% higher than that of the diamond bur.

The fissure bur and diamond bur generated comparatively lower lateral-cutting forces.

This difference is related to the bur design. The round bur has a spherical cutting surface, which creates a larger cutting area during sideways movement.

By comparison, the fissure bur has grooves and defined cutting edges that support a more controlled lateral-cutting action. This is one reason why a fissure bur may be suitable when shaping or contouring enamel surfaces.

Which Bur Generated the Lowest Temperature?

Heat management is another important factor during enamel preparation.

The fissure bur generated the lowest drilling and lateral-cutting temperatures among the three burs tested. The diamond bur generated the highest temperatures.

During lateral cutting, the average temperature produced by the diamond bur was approximately 24.23% higher than that of the fissure bur and 14.17% higher than that of the round bur.

The study linked these findings to contact area, friction and chip removal.

The fissure bur has a structure that supports chip evacuation. Removed material can move away from the cutting area more efficiently along the bur surface. This helps reduce chip blockage and friction.

The diamond bur removes material through multiple abrasive diamond grits. However, it does not have the same chip-discharge structure as a fissure bur. Debris may become trapped between the bur and enamel surface, increasing friction and heat generation.

The round bur also presents limitations during chip evacuation. Its spherical surface increases the friction area, and removed material may fall back into the drilled area.

These findings do not mean that the fissure bur eliminates the need for cooling. Adequate irrigation remains important during clinical procedures. However, the study shows how bur geometry itself can affect temperature generation.

Which Bur Produced the Best Drilling Quality?

The diamond bur produced the best drilling quality at the entrance of the prepared hole.

Its abrasive surface contains multiple diamond grits. These act as micro-cutting edges and remove smaller amounts of material during the cutting process. This resulted in a cleaner hole entrance than the other bur types tested.

However, the study also identified a trade-off.

Although the diamond bur produced the best drilling quality, it had the lowest drilling precision. The irregular dimensions of the diamond grits affected the dimensional accuracy of the drilled area.

The fissure bur produced poorer drilling quality because its tip contacted and compressed the brittle enamel during penetration. The round bur also caused material stripping around the hole entrance due to its curved cutting edges.

This demonstrates why drilling quality and drilling precision should not be treated as the same measurement. A preparation may appear cleaner at the entrance while still being less dimensionally accurate.

Which Bur Produced the Best Surface Quality During Lateral Cutting?

The fissure bur achieved the best surface quality during lateral enamel cutting.

The study reported that the fissure bur produced a smooth, vertical-groove surface. It was also the only bur among the three tested that generated a flat surface after lateral cutting.

The diamond bur produced a stepped surface due to the irregular size of the diamond grits. Larger abrasive particles created deeper grooves, resulting in an uneven surface pattern.

The round bur produced a relatively smooth spherical surface, but scratches were still observed. Its curved geometry also limited its ability to create a flat prepared surface.

For dentists, this is one of the most clinically interesting findings. A fissure bur may be particularly relevant where controlled lateral shaping and a flatter surface are required.

Why Tooth Surface Orientation Matters

The tooth surface itself also affected bur performance.

Compared with the buccal or lingual and mesial or distal surfaces, the occlusal surface produced approximately 10% lower lateral-cutting force but around 9% higher temperature.

The researchers linked this difference to the orientation of enamel rods.

During lateral cutting of the occlusal surface, the bur axis was more closely aligned with the enamel-rod direction. This allowed the rods to be cut more effectively, reducing the cutting force.

However, more effective cutting also increased friction and temperature.

On the buccal, lingual, mesial and distal surfaces, the bur interacted differently with the enamel rods. The altered orientation increased resistance to cutting and affected the resulting surface quality.

This finding highlights an important point: bur performance does not depend only on the instrument. The direction of cutting and the tooth surface also matter.

Clinical Interpretation: Match the Bur to the Procedure

The study does not suggest that dentists should replace one bur type with another in every situation.

Instead, it shows why different burs may be suitable for different tasks.

These findings should be interpreted carefully. The study was conducted in vitro using a controlled experimental system. Clinical outcomes also depend on handpiece performance, irrigation, bur wear, applied pressure, access, visibility and operator technique.

Nevertheless, the study provides a practical explanation for why bur shape matters.

Conclusion

There is no single best dental bur for every enamel-cutting procedure.

The round bur generated the lowest drilling force, making it mechanically suitable for initial penetration. The diamond bur produced the best drilling quality at the entrance of the prepared hole, although its dimensional precision was lower.

The fissure bur showed important advantages during lateral enamel cutting. It generated the lowest drilling and lateral-cutting temperatures and produced the best surface quality during sideways shaping. It was also the only bur tested that created a flat surface after lateral cutting.

For dentists, the key message is not to select a bur based on habit alone. Bur geometry should be matched to the intended cutting action.

A round bur, diamond bur and fissure bur each perform differently because each has a distinct structure and cutting mechanism. Understanding these differences can support more controlled enamel preparation and more informed bur selection.

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