Abstract
A peg-shaped lateral incisor does not always require tooth reduction to improve its form. When enamel is healthy and sufficient space is available, direct composite bonding can add the missing tooth volume while preserving natural tooth structure.
Recent clinical reports describe additive and digitally guided composite techniques for peg laterals using diagnostic wax-ups, silicone indexes and injectable or layered resin composite. The challenge is not simply closing a space. Successful reshaping requires control of optical width, transitional line angles, proximal contour, emergence profile and surface texture.
This article focuses specifically on the additive composite workflow and how finishing and polishing help transform added resin into natural anterior anatomy.
Why Is a Peg Lateral an Additive Restorative Problem?
A peg lateral is a form of localized microdontia, most commonly involving a maxillary lateral incisor.
In many cosmetic cases, the problem is not damaged tooth structure. It is missing volume.
The crown may be too narrow, tapered or deficient proximally while the existing enamel remains healthy. This creates a different restorative question:
Instead of asking what should be removed, what anatomy needs to be added?
A 2025 clinical report by Alshehri restored bilateral peg-shaped lateral incisors using full-contour direct resin composite. Diagnostic planning and a silicone index were used before the restorations were subsequently contoured, finished and polished. The report highlighted direct composite as a conservative approach for correcting peg-lateral morphology.
The Cosmetic Case
Consider a patient who has completed orthodontic alignment but still presents with a narrow maxillary lateral incisor.
The tooth is:
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vital
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caries-free
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well aligned
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surrounded by healthy gingiva
Yet its reduced width creates visible spacing and an unbalanced anterior smile.
The restorative objective is therefore not simply:
Close the gap.
It is:
Create a lateral incisor that belongs beside the central incisor and canine.
That requires morphology, not just material.
Step 1: Determine Where the Missing Volume Belongs
Before composite is placed, clinicians should assess where additional volume is actually required.
Important parameters include:
Mesiodistal width
The physical width of the crown from mesial to distal.
Proximal contour
The shape created as the facial surface transitions toward the contact areas.
Emergence profile
The cervical contour of the restoration as it emerges from the gingival region.
Incisal embrasure
The space created between adjacent incisal edges.
Optical width
How wide the tooth appears when viewed from the front.
These parameters are related but not identical.
Simply adding equal amounts of composite to both proximal surfaces can produce an oversized or rectangular restoration.
Step 2: Plan Before Bonding
Recent reports increasingly describe a restoration-driven workflow rather than freehand addition without a predetermined form.
A 2024 clinical report by Alyahya and colleagues used an injectable composite resin technique for congenitally peg-shaped lateral incisors. The technique transferred planned morphology through a transparent index rather than relying entirely on intraoral freehand contouring.
Digital workflows can also combine:
Digital scan → Diagnostic wax-up → Printed model → Silicone index → Composite transfer
A 2023 report involving microdontia and anterior spacing used digital wax-ups and 3D-printed models to fabricate transparent indexes for a composite injection technique. The authors described the approach as non-invasive and reversible while allowing planned tooth dimensions to be transferred clinically.
For peg laterals, this helps answer a critical question before bonding begins:
Where should the final facial, palatal and proximal surfaces actually be?
Step 3: Build Anatomy, Not Just Width
Direct composite reshaping is fundamentally an additive dentistry procedure.
Depending on the chosen technique, composite may be placed incrementally or transferred through an injectable composite index.
A layered workflow may progress through:
Palatal shell → Proximal form → Body volume → Facial contour → Incisal anatomy
The proximal areas deserve particular attention.
If too little composite is added cervically, the restoration may still appear tapered.
If too much is added, an overcontoured cervical profile may develop.
The target is a smooth transition from the gingival region into the crown without creating unnecessary bulk.
The Special Vocabulary: Transitional Line Angles
One of the most useful concepts when reshaping peg laterals is the transitional line angle.
These are the visually important transitions between the facial surface and proximal surfaces.
They influence how light reflects from the restoration.
This means two restorations with the same measured width can appear dramatically different.
Moving the line angles outward can make the visible facial surface appear broader.
Moving them inward can make the tooth appear narrower.
This is why optical width matters in cosmetic restorative dentistry.
A peg lateral restoration can have the correct physical dimensions but still look unnatural if its line angles are misplaced.
Step 4: Finishing Becomes Part of the Design
After polymerization, the restoration may contain the correct volume but still lack natural anatomy.
Finishing should establish:
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mesial and distal line angles
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facial convexity
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proximal transitions
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cervical contour
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incisal embrasures
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primary surface anatomy
This is where rotary finishing instruments can become useful.
The MR.Bur Super Fine Finishing Flame Diamond Bur FG is available in narrow flame-shaped geometries, including small head diameters such as the 68SF series. Its geometry allows localized access where controlled contour refinement is required.
For a direct peg-lateral restoration, the bur should be considered a contouring instrument, not a substitute for polishing.
Light, controlled passes can be used to refine excess composite and transitional areas while preserving the volume that was intentionally added.
The objective is:
Add first → Define anatomy → Remove only what disrupts the planned form
Step 5: Why Surface Texture Changes the Final Smile
A perfectly shaped composite restoration can still appear artificial if its surface reflects light differently from adjacent enamel.
This introduces another important term:
Surface roughness
Finishing instruments create a surface that must subsequently be refined through polishing.
A 2023 systematic review by Devlukia, Hammond and Malik evaluated different finishing and polishing protocols for direct resin composites. The review found insufficient evidence to identify one universally superior composite-polisher combination, but importantly concluded that the finishing procedure before polishing can influence the final surface roughness.
This supports a sequential rather than interchangeable approach:
Contour → Fine finish → Polish
For the polishing stage, the MR.Bur Composite Polishing Diamond Polisher 6002 uses a two-step medium and fine diamond-impregnated silicone sequence for low-speed contra-angle application.
In a peg-lateral restoration, polishing follows anatomical finishing. Its role is to progressively refine the composite surface after the intended tooth form has already been established.
Should Every Surface Become Completely Flat and Glossy?
No.
Natural anterior teeth are not perfectly flat.
They contain subtle:
primary anatomy, representing the overall crown form, and
secondary anatomy, including developmental depressions and surface transitions.
Over-finishing can erase these features.
Likewise, aggressive polishing can flatten carefully positioned line angles.
The goal is therefore not simply maximum smoothness at any cost.
It is a surface that combines:
Anatomy + Controlled texture + Appropriate gloss
so the composite interacts with light more like the adjacent enamel.
What About Longevity?
Direct anterior composite restorations require maintenance.
A systematic review involving more than 75,000 anterior composite restorations found considerable variation in reported survival, with fracture being the most frequently reported cause of failure. Adhesive technique, restorative material and clinical factors also influenced outcomes.
For additive peg-lateral bonding, long-term review should therefore assess:
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marginal integrity
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surface staining
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gloss retention
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fracture or chipping
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proximal contacts
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occlusion
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periodontal response
Because composite is repairable, localized defects may sometimes be corrected without replacing the entire restoration.
Clinical Takeaway
Direct composite bonding for peg laterals is not simply space closure.
It is the controlled reconstruction of missing anterior tooth anatomy.
Digital planning or a silicone index can establish the intended volume. Composite creates the new form. Finishing then defines line angles, optical width and proximal contour, while polishing refines the final surface.
The workflow can be summarized as:
Plan → Add → Shape → Define Line Angles → Finish → Polish → Review
In additive cosmetic dentistry, success depends not on how much tooth structure can be removed, but on how precisely the missing anatomy can be recreated.
