Recommended post length in primary anterior teeth

• Remove approximately 4 mm of obturating material, then place a 1 mm glass-ionomer barrier over the remaining obturation. This leaves an effective 3 mm post space.
• The coronal extension should be only what is needed to retain the composite core, commonly about 2-3 mm beyond the CEJ, while avoiding occlusal interference.
• Do not use the conventional permanent-tooth principle of a long post. In primary teeth, a longer post may interfere with physiologic root resorption and exfoliation.

“In both cases, the intracanal post was restricted to the coronal 3 mm of the root canal. This is the accepted short-post approach for primary incisors, intended to provide retention while avoiding interference with physiologic root resorption.”

Authentic references for the 3 mm length

1. Seraj B, et al. Push-out bond strength of different intracanal posts in the anterior primary teeth according to root canal filling materials. The authors specifically state that glass fiber post length in the canal did not exceed 3 mm to avoid interference with normal root resorption. Read the full-text study.
2. Bolla D, et al. Efficacy of Reverse Metal vs Glass Fiber and Polyethylene Fiber Posts in Esthetic Rehabilitation of Severely Decayed Primary Anterior Teeth: A Randomized-controlled Clinical Trial. Int J Clin Pediatr Dent. 2026;19(3):375-381. In their glass fiber and Ribbond protocol, 4 mm of obturation was removed and a 1 mm GIC base was placed, leaving a 3 mm intraradicular post length. The polyethylene fiber was cut to 6 mm: 3 mm within the canal and 3 mm for core build-up. See the clinical trial. PMID: 42328227.
3. Sholapurmath SM, Anand S. Use of reversed metal post for the restoration of severely decayed primary anterior teeth. J Indian Soc Pedod Prev Dent. 2010;28:21-25. The principle commonly cited in primary anterior post restorations is placement within the coronal 3 mm to prevent disturbance of physiologic resorption.

How to defend using different post types in two different cases

Case using a prefabricated glass fiber post

“A prefabricated glass fiber post was selected because the canal anatomy allowed passive adaptation of a standardized post without unnecessary canal enlargement. It provides a predictable chairside technique, good esthetics, and a modulus of elasticity closer to dentin than metal posts. This helps distribute functional stresses more favorably and is appropriate when there is adequate canal form for post adaptation.”

• Esthetic and translucent beneath a composite restoration or strip crown.
• Prefabricated and standardized, so it is relatively simple and time-efficient.
• Good choice where the post fits passively and there is no need to remove additional radicular dentin.
• Avoid saying the post “strengthens the root.” Its main purpose is retention of the coronal restoration, not reinforcement of tooth structure.

Case using a Ribbond post

“Ribbond was selected because it is a polyethylene fiber ribbon that can be customized to the canal shape. In a flared or irregular canal, a prefabricated glass fiber post may leave a thick, non-uniform layer of resin cement or composite. Ribbond adapts to the canal contours, permits a conservative customized post-core design, and avoids further canal preparation.”

• Flexible, adaptable ribbon form.
• Better suited to irregular or non-circular canals.
• Can be integrated with composite in a direct chairside technique.
• Esthetic because it is translucent/colorless within composite.
• Particularly useful where a conventional prefabricated post would have poor adaptation or require enlargement of an already thin primary root.

A concise viva-ready defense

“Both teeth required an intracanal retainer because coronal tooth structure was insufficient for reliable composite retention after pulpectomy. In both cases, I restricted the post to the coronal 3 mm of the canal to preserve the physiologic resorption pathway. The post type was selected according to canal morphology rather than using one material routinely.

In the tooth with a relatively narrow and regular canal, a prefabricated glass fiber post gave passive adaptation and a predictable esthetic restoration. In the tooth with a wider or more irregular canal, Ribbond was preferred because it could be customized to the canal contour, minimizing further dentin removal and avoiding a thick, uneven resin interface. Thus, both choices were conservative, esthetic, and anatomy-driven.”

Important evidence-balanced point

“Ribbond was selected for its adaptation advantage in this specific canal, not because it is universally more retentive than glass fiber.”

Best reference for your presentation

Reference for 3 mm intracanal post length

“The intraradicular post length was restricted to 3 mm, based on Memarpour et al., who used a 3 mm intracanal fiber-post extension in primary teeth and stated that this depth does not interfere with physiologic root resorption.”

Strong clinical evidence comparing glass fiber and polyethylene fiber

• Glass fiber post: 93.3% complete retention
• Polyethylene post: 86.7% complete retention
• Composite post: 60% complete retention

Optional mechanical-comparison reference

Viva defense using only these references

“I used a short 3 mm intraradicular post in both cases, as primary teeth undergo physiologic root resorption. Memarpour et al. used 3 mm intracanal extensions for both glass and polyethylene fiber posts and reported that this depth does not interfere with normal root resorption.

Both glass fiber and Ribbond are evidence-supported esthetic intracanal retainers. In the randomized clinical study by Mehra et al., both materials had acceptable 12-month retention, although glass fiber showed slightly higher retention. Therefore, my selection was based on canal morphology and adaptation, rather than considering one post universally superior.

I selected the prefabricated glass fiber post where passive adaptation was possible in a regular canal. I selected Ribbond where a customized, flexible fiber was more suitable for an irregular or flared canal, allowing adaptation without further removal of radicular dentin. This is consistent with the systematic review by Shanmugam et al., which supports both systems but notes the limited and heterogeneous evidence base.”

“Because primary roots undergo physiologic resorption, intracanal retention should be conservative and restricted to the coronal portion of the canal. Therefore, I used a 3 mm intraradicular post extension.”

Post length: 3 mm within the coronal root canal, preserving the physiologic resorption pathway in primary teeth.
References: Fuks et al., in Pediatric Dentistry: Infancy Through Adolescence, 6th ed., 2019; Memarpour et al., Restor Dent Endod, 2013.

For transverse maxillary expansion / posterior crossbite

1. Define the required expansion on study models or digital scans
   Aim for correction of the crossbite plus a small amount of overcorrection, usually to a slight buccal relationship of the maxillary palatal cusps to the mandibular buccal cusps.
2. Remove the appliance from the bands if it is already cemented.
3. Use a three-prong plier or bird-beak plier to produce a symmetric lateral expansion.
   • Open the appliance in the transverse plane.
   • The main adjustment is made by widening the posterior sections/outer helices and lateral arms equally on both sides.
   • Preserve the basic loop form. Do not simply flatten the helices, as this changes the force system unpredictably.
4. Check passivity of the bands and symmetry on the model before recementation.
   The appliance should seat fully without rocking or distortion of the molar bands.
5. Reactivate gradually, commonly at follow-up reviews approximately every 4-6 weeks, based on crossbite correction, molar inclination, periodontal condition, and patient comfort.

If the indication is molar derotation

Viva-style answer

“A quad helix is activated extra-orally with a three-prong or bird-beak plier. For bilateral slow maxillary expansion, I activate it symmetrically by widening the posterior helices and lateral arms while maintaining the loop configuration. I check the amount of activation on the study model, ensure the bands seat passively, and review periodically for controlled dentoalveolar expansion and correction of the crossbite. If the goal is molar derotation, I use localized asymmetric activation rather than generalized expansion.”

Important points

• Quad helix produces slow dentoalveolar maxillary expansion, not the same force system as a Hyrax rapid maxillary expander.
• Avoid excessive single activation. It can cause pain, molar tipping, soft-tissue impingement, unwanted rotation, and appliance distortion.
• Make the activation symmetric for bilateral crossbite and asymmetric only when a unilateral correction or molar derotation is planned.
• Check that helices do not impinge on palatal soft tissue and that the appliance is not contacting erupted premolars or interfering with occlusion.