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Harmony restored: A case study on short teeth, gummy smile and a lack of ferrule effect

By Dr Andrew See

BDS Hons (Syd), FRACDS, MSc(Lond), PGDipDentImplantology,

FCGDENT(UK), FICOI, MFDS RCSEng

Abstract
This clinical case study delves into the realm of aesthetic dentistry as we unravel a compelling case that showcases the successful treatment of a complex dental scenario involving short central incisors, a gummy smile, and the challenge of a lack of ferrule effect. This case explores the intricate approach taken to address these interconnected issues offering practical insights for managing such challenging situations. Treatment planning emphasised the necessity of a holistic treatment approach for optimal results. Full-face photographs are included with written consent from the patient. 

Introduction

In the world of aesthetic dentistry, achieving the perfect balance between form and function is an art. Short teeth, often accompanied by a gummy smile, present a unique set of challenges that demand a meticulous treatment strategy. This case study delves into the assessment, planning, and execution of crown lengthening surgery, offering a roadmap for practitioners seeking insights into managing similar cases.

A patient-centered approach is paramount, ensuring transparent communication of all viable options. The case study presented herein evaluates the integration of gingival analysis into the treatment plan, showcasing how to address these often interrelated components.

Short Teeth

Recognising short anterior teeth is crucial in the practice of aesthetic dentistry.The average dimensions of an adult central incisor according to Magne 2003 has a width of 9.1mm and a length of 11.7mm. However, using general tooth dimensions does not take into account the differences in stature of the individual, the difference in size seen in male and female patients and the racial differences in dimensions.  What is more clinically useful is to use the crown width to length ratio.

Analysis of this ratio shows that unworn central incisor teeth have an average ratio of 78%, in Caucasians and a ratio of 72% in Asians (Magne 2022).

Where we can start to diagnose short teeth is when the length of the central incisor becomes similar to the width, resulting in a tooth that assumes a square-like appearance.

The literature is scarce in pinpointing the precise threshold, butMagne 2022gives us a starting point. He defines worn teeth with a ratio of 87%, providing a basis for labelling a tooth as short.

Figure 1 highlights the visual change where short teeth with a ratio over 100% was treated with crown lengthening surgery and restorative work, resulting in a more harmonious final ratio of 78%.

ry ratio
Fig 1. Analysis on central incisor ratios

After establishing the diagnosis of a short central incisor, a crucial decision revolves around whether to enhance it’s length through incisal edge addition of surgical apical relocation of the gingival margin. This decision-making process is pivotal, as merely extending the length without a comprehensive understanding of underlying factors may yield aesthetically displeasing outcomes concerning the patient’s face and smile. Furthermore, it has the potential to negatively impact occlusion by modifying the jaw’s guidance pattern and restricting the envelope of function.

In addition, successful management of short teeth necessitates the identification of aetiological factors to prevent subsequent damage post-treatment. The common causes of short anterior teeth stem from attrition, erosion, a history of trauma and iatrogenic causes from adjustments made to the incisal edge.

Gummy Smile

A gummy smile can be considered as more than 2.0mm of gingival display during a high smile (Peck 1992).While this criterion may be subjective across various cultures, Kokich 1999 observed that an upper gingival display of ³ 4.0mm during a high smile line was considered as unattractive by clinicians and laypeople. A comprehensive understanding of the diagnosis of a gummy smile is required given that treatment options are aetiologically specific and incorrect treatment could result in undesirable and irreversible outcomes.

Robbins and Rouse in 2016 outlined the critical factors for diagnosing a gummy smile. In summary, this involves assessing:

  • Facial proportions
  • Lip length and mobility
  • Orientation of the gingival line
  • Central incisor display in repose
  • Central incisor dimensions
  • Location of the cementoenamel junction relative to the gingival margin

Analysis of these factors helps us formulate an accurate diagnosis that allows us to form a treatment plan for addressing the complexities of gummy smiles.

Case Study

A 33-year-old woman presented wanting an improvement of her existing crowns on her central incisors. Her main concerns were the short appearance of her central incisors, her gummy smile and the gingival margin discolouration. However, her main motivation for treatment was her crowns had become loose.

Medical and Dental History

Her medical history was unremarkable. The existing endodontic treatment and crowns were placed when she was 10-years-old after trauma. She felt that one of the crowns was mobile and would like a second opinion. She had been previously recommended extraction of the central incisors and placement of dental implants as there was limited tooth structure present.

She was strongly against having orthodontics and implant treatment.

Clinical findings

The patient had an unremarkable extra-oral examination except minor asymptomatic clicking in her TMJ.

During a normal smile and a high smile, she had 4.0mm and 6.0mm of gingival display respectively.At repose she had a central incisal display of 3mm.21 had a periapical area had a slight swelling that was slightly tender to palpation.

General periodontal condition was sound. She had bleeding on probing and gingival discolouration around 11 and 21.

Neither 11 and 21 were tender to percussion.Both 11 and 21 crowns were mobile.

The crowns were easily removed and 11 had an absence of ferrule and 21 preparation was extremely tapered (Figure2).

lack of ferrule
Fig. 2. Absence of ferrule on 11 and unfavourable tapered preparation on 21.

Radiographic findings

11 and 21 was previously endodontically treated and had been restored with a post, core and crown. 21 had a periapical radiolucency present (Fig 3).

21 cbct 1
Fig 3. CBCT show the extent of the periapical radiolucency present on 21.

Clinical summary

From the findings it was concluded that she had a gummy smile. 21 had apical periodontitis and loss of retention of 11 and 21 post, core and crown restorations.

The findings highlighted multiple issues such as compromised endodontic treatment, absence of ferrule effect and persistent inflammation likely due to invasion of biologic width and misfitting crowns.

The width/length ratio of 11 and 21 was 94% and 98% respectively indicating short teeth (Figure4).

ratio analysis 1
Fig 4. Analysis of width/length ratio of the central incisors helps us determine that they are short.

Treatment Options

Simplifying the treatment plan for this case involved breaking it down into smaller objectives aligned with the patient’s expectations.

Following a collaborative discussion,it was evident that the patient’s primary goal was to defer implant treatment and maintain her central incisors as long as possible. The ultimate objective was to achieve resolution to the aesthetic concerns linked with a gummy smile and ensure the stability of the final restorations.

A case could be made for extraction and implant therapy to replace the central incisors, particularly due to the insufficient coronal tooth structure for a sufficeint ferrule effect. The evidence strongly suggests that without adequate ferrule effect that a poor clinical outcome is very likely (Juloski et al 2012).

Nevertheless, taking into account the patient’s age, the high smile line and high patient expectations, she opted to attempt to keep the central incisors acknowledging the risks, limitations and the potential for eventual failure.

Considering this, the treatment sequence becomes more apparent. This involves addressing the risk factors that may negatively impact on the desired outcome then aiming toimprove function and aesthetics.

The initial step in the treatment process involvedassessing the potential resolution of the endodontic lesion associated with tooth 21. To address this, a referral was made to an Endodontist for potential retreatment of both 21 and 11.

Simultaneously, a crucial concern emerged regarding insufficient tooth structure, specifically the absence of a ferrule effect. As per Juloski et al.’s recommendations in 2012, the absence of coronal tooth structure suggests considering orthodontic extrusion as the primary option. However, given the patient’s reluctance to undergo orthodontics, an alternative approach was pursued – functional crown lengthening surgery.

The location for the final gingival margin was calculated by evaluating the gingival line, a reference line from the gingival margin of the canine to canine, establishing the appropriate level for the gingival margins of the central incisors.

Functional crown lengthening not only facilitated the enhancement of the gummy smile but also addressed concerns related to the width/length ratio of the central incisors and encroachment on biologic width.

Upon conducting an aesthetic examination and analysing the ideal width/length ratio, it was determined that the optimal gingival margin should be positioned 2mm apical to the current location, considering the constraint that the width of teeth 11 and 21 cannot be altered (see Fig 5).

calculations 1
Fig 5. Determination of the future gingival margin position.

The patient was informed about the aesthetic considerations during the treatment, emphasising that following crown lengthening surgery, the root surface of the teeth would be exposed, leading to the formation of a black triangle between her central incisors. This condition would persist until the provisional crowns were placed.

Botox treatment was also discussed to improve her overall gummy smile but was declined.

Treatment Sequence

Functional Crown Lengthening

Prior to the completion of retreatment by the endodontist, functional crown lengthening was necessary to provide additional coronal tooth structure for isolation. This involved ostectomy and osteoplasty. Bone was removed 3.0mm from the future crown margin position respecting biologic width. An apically positioned flap was indicated for crown lengthening as the width of the keratinised attached gingiva was not sufficient for gingivectomy (see Fig 6).

functional crown lengthening
Fig. 6. Functional crown lengthening surgery with circumferential osseous surgery. The flap apically repositioned.

The healing process progressed uneventfully, and sutures were removed after a two-week period (see Fig 7).

suturing
Fig 7.Uneventful healing after 2 weeks.

Endodontic Retreatment

21 cbct 2
Fig 8. CBCT 6 month post endodontic retreatment shows resolution of the periapical radiolucency on 21.

Restorative Phase

Restorative treatment involved placement of a fibre post to enhance the retention of the core material. Special attention was given to avoid unnecessary enlargement of the existing canal, aiming to preserve as much tooth structure as possible to protect the teeth from fracture. The post space was cleaned and free of gutta percha. The post prep space was completed leaving 4.0mm of gutta percha in place. The post size selection was based on the largest post that would achieve passive fit in the canal and modified accordingly. A 1.9mm RelyXFibre post (3M) was cemented with RelyX Universal cement (3M) in a self-adhesive mode (Fig 9).

post cementation
Fig 9. Restorative phase began after there was radiographic evidence of resolution of the periapical radiolucent lesion. A fibre post was used to retain the core. Care taken to bond under rubber dam isolation and prepare the post space leaving the maximum amount of tooth structure.

A composite core was placed using Scotchbond Universal Plus (3M) and FiltekOne Bulk Fill (3M) and the final crown preparations were carried outwith a goal of achieving 1.5mm of circumferential ferrule.

The polyether (3M Impregum) impression was taken using a double cord technique and the preparations were provisionalised with 3M Protemp 4 and Tempbond Clear (Kerr).

Bonding

The provisionals were removed and the definitive crowns were issuedunder rubber dam isolation.

The preparations were microetched with 50mm Aluminium Oxide and the crowns were adhesively bonded with Scotchbond Universal Plus (3M) and RelyX Universal cement (3M). 

The occlusion was adjusted and finalisedwith a mutually protective occlusal scheme.

Conclusion

The final outcome enhanced the harmony in the patient’s smile by improving the proportions of the central incisors (Fig 10, 11).

contraster
Fig 10. Functional crown lengthening surgery resulted in enhanced central incisor width/length ratio.

The integration of checklists and decision-making workflows, coupled with a patient-centered approach, plays a pivotal role in informed consent and meeting patient expectations. The article invites a holistic perspective in addressing short teeth and gummy smiles, offering a roadmap to navigate such scenarios.

glamour shot
Fig 11. Patient after the completion of treatment. Harmony restored. (Endodontist: Dr David Barnard;Dental technician: Riccardo Borgonovo)

 

Author Bio

website dr see 2022 profile 21

Dr Andrew See is an expert in Aesthetic Dentistry with over 20 years of dedicated experience. His qualifications include a Masters in Aesthetic Dentistry from the prestigious King’s College London and a Postgraduate Diploma in Dental Implantology. Dr See completed his Fellowship by primary and secondary examinations for The Royal Australasian College of Dental Surgeons (FRACDS). Dr. See’s commitment to excellence makes him a sought-after resource in the field of Aesthetic Dentistry.His commitment to education and innovation is evident through his key opinion leader role for 3M Australasia and contributions as a speaker for CPD sessions.

For more resources and insights, visit www.drandrewsee.com or connect on social media: Instagram – @dr.andrewsee, YouTube – @dr.andrewsee, Email – andrew@drandrewsee.com

For the full list of references, contact Australiasian Dentist on: gapmagazines@gmail.com

REFERENCES

Juloski J, Radovic I, Goracci C, Vulicevic ZR, Ferrari M. Ferrule Effect: A Literature Review. J Endod. 2012;38(1):11-19.

Kokich VO Jr, Kiyak HA, Shapiro PA. Comparing the Perception of Dentists and Lay People to Altered Dental Esthetics. J Esthet Dent 1999;11:311–24.

Magne P, Galluci GO, Belse UC. Anatomic Crown Width/Length Rations of Unworn and Worn Maxillary Teeth In White Subjects. J Prosthet Dent. 2003;89(5):453-461.

Magne P, Belser U. Bonded Porcelain Restorations: A Biometric Approach. 2003. USA: Quintessence Publishing Co.

Magne P, Belser U. Biometic Restorative Dentistry. 2022. USA: Quintessence Publishing Co.

Peck S, Peck L, Kataja M. Some Vertical Lineaments of Lip Position. Am J Orthod Dentofacial Orthop. 1992; 101(6):519-524.

Robbins JW, Rouse JS. Global Diagnosis. 2016. USA: Quintessence Publishing Co.

COMPLIMENTARY GUIDE: The Gummy Smile Decision-Making Tree.

Based on the ground-breaking research of Robbins and Rouse in their 2016 Global Diagnosis, Dr See’s Gummy Smile Decision-Making Tree is your practical guide to navigating the intricate landscape of gummy smile treatments. This meticulously designed tool empowers practitioners like you to make informed decisions during treatment planning.Head to www.drandrewsee.com to get to get your copy of this comprehensive guide.

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