Periodontal Phenotypes, Recession & Anomalies

Question 1

Define the terms genotype, phenotype and morphotype

Answer 1

Genotype
• The set of genes or genetic composition/sequence of an individual organism
• Non- modifiable

Phenotype
• The observable characteristics of an individual organism, which are influenced by both its genotype and the environment

Morphotype
• Individual or set of individuals within a population with a distinctive physical characteristic (E.g. alveolar bone morphotypes – scalloped, flat)

Question 2

Define ‘normal mucogingival condition’

Answer 2

Absence of pathosis or disease’ (i.e. gingival recession, gingivitis, periodontitis), with variability evident amongst individuals

Question 3

Give examples of mucogingival conditions

Answer 3

Lack of keratinized tissue, position and shape of frena and shallow vestibular depth can be associated with periodontal health

Question 4

List the three types of periodontal phenotypes

Answer 4

Thin scalloped biotype

Thick flat biotype

Thick scalloped biotype

Question 5

For the thin scalloped biotype, list:

• Gingival thickness/keratinised tissue
• Born morphotype
• Tooth dimension

Answer 5

Gingival thickness/ keratinised tissue:
• Narrow zone of keratinised gingiva

Born morphotype:
• Thin alveolar bone

Tooth dimension:
• Slender, triangular crown

Question 6

For the thick flat biotype, list:

• Gingival thickness/keratinised tissue
• Born morphotype
• Tooth dimension

Answer 6

Gingival thickness/ keratinised tissue:
• Thick, fibrotic gingiva

Born morphotype:
• Thicker alveolar bone

Tooth dimension:
• Square shaped teeth

Question 7

For the thick scalloped biotype, list:

• Gingival thickness/keratinised tissue
• Born morphotype
• Tooth dimension

Answer 7

Gingival thickness/ keratinised tissue:
• Fibrotic gingiva with pronounced gingival scalloping

Born morphotype:
• Thick

Tooth dimension:
• Thin, slender narrow teeth

Question 8

Describe the assessment methods used to determine periodontal biotype

Answer 8

• Transgingival probing (accuracy to the nearest 0.5 mm), performed under local anaesthesia
• Ultrasonic measurement: Probe visibility after its placement in the facial sulcus

Question 9

What are the measurements for ‘thin’ and ‘thick’ gingiva

Answer 9

Gingiva is defined as thin (≤1.0 mm) or thick (>1mm) upon the observation of the periodontal probe visibility through the gingiva

Question 10

How do you measure Keratinised Tissue Width (KTW) and bone thickness?

Answer 10

KTW
• Easily measured with a periodontal probe positioned between the gingival margin and the muco-gingival junction
• 2mm of KTW and 1mm of attached gingiva are desirable around teeth to maintain periodontal health

Bone Thickness
• Assessment through Cone Beam-computed Tomography (CBCT) has high diagnostic accuracy, exposure to radiation has potential harmful effect

Question 11

How can tooth positioning affect phenotype?

Answer 11

For example, teeth tilted or rotated labially
• the labial bony plate is thinner and located further apically than on adjacent teeth
• the gingival margin is recessed apically to follow the bone, leading to exposure of the root
• the gingiva is bulbous on the lingual surface
• the bone margins are closer to the CEJ

Question 12

Mention the characteristics of a thin periodontal biotype and how brushing or restorations serve as risk factors for gingival recession

Answer 12

• Decreased width of keratinized tissue
• Reduced thickness of alveolar bone due to abnormal tooth position in the arch
• Studies have found poor toothbrushing habits to be potential risk factors for recession: hard pressure, hard bristles, duration of brushing
• Restorative crowns that go sub gingivally in a thin- biotype can increase gingival recession
• The apical extent of the restorative margin should ideally be a minimum of 2.5mm from alveolar crest to avoid violation of biologic width, leading to: gingival recession and bone loss

Question 13

List the classifications for recession

Answer 13

• Class I: recession does not extend to the mucogingival junction and there is no tissue loss in the interproximal area
• Class II: recession extends to or beyond the mucogingival junction. There is no periodontal loss in the interproximal area
• Class III: recession extends to or beyond the mucogingival junction. Bone or soft tissue loss is present in the interdental area
• Class IV: recession extends to or beyond the mucogingival junction.

Question 14

Consider impact of interproximal recession on clinical attachment

Answer 14

• CAL: measured from the CEJ to the base of the sulcus

Interproximal recession can increase CAL

Question 15

Discuss treatment considerations for patients without recession for thick periodontal biotypes

Answer 15

Thick gingival biotype

• Prevention through good oral hygiene instruction and monitoring of the case

Question 16

Discuss treatment considerations for patients without recession for thin periodontal biotypes

Answer 16

Thin gingival biotype
• Since there is a greater risk for development of recession, prevention and careful monitoring should be employed
• If there are areas with severely thin gingival biotype, mucogingival surgery may be considered to prevent future mucogingival damage

Question 17

Discuss the prevention/ control approach of treatment for patients with recession

Answer 17

• Conducting periodontal charting and monitoring exposed root surfaces for deterioration
• Measure the amount of keratinized tissue width
• Treatment determined by severity of periodontal and dental lesions

Question 18

Discuss the treatment oriented approach of treatment for patients with recession and thin biotypes

Answer 18

• Presence of cervical caries or non-carious cervical lesions (NCCL)
• Mucogingival surgery for root coverage and CEJ reconstruction and other restorative procedures