Molecular mechanisms in palatal rugae development

Minor physical anomalies including palatal rugae pattern and palatal dimensions in children with sickle cell disease: A cross-sectional analytical study

Background

Sickle cell disease (SCD) is the most common hereditary hemoglobinopathy, which delays growth leading to an altered skeleton and craniofacial pattern. Palatal rugae patterning has been considered the regulator of the development of the palate. The purpose of the research work was to study the morphology of the palate, rugae pattern, and its dimensions in SCD children and compare them with healthy normal children, and to evaluate its role as minor physical anomalies (MPAs).

Methods

A cross-sectional case-control study was designed as per STROBE guidelines. The sample comprised 50 children diagnosed with sickle cell disease (Group SCD) and 50 normal healthy children as control (Group C) belonging to the same age group (10-18 years). Dental impressions were made, followed by the pouring of dental casts. The length of the palatal rugae was measured and categorized into primary (>5 mm), secondary (3 mm-5 mm), and fragmentary rugae (<3 mm). The shape of each primary palatal rugae was identified and categorized as curved, wavy, straight, circular and non-specific. Linear and angular measurements of the palatal rugae patterns and palatal dimensions (width, height, area) were measured and recorded.

Results

The total number of palatal rugae and fragmentary rugae was lesser in Group SCD than in Group C (p < 0.05). The depth of the palate was significantly increased, whereas the area of the palate significantly decreased in Group SCD.

Conclusions

The children with SCD showed distinctive palatal rugae patterns and dimensions when compared with normal healthy children that can be attributed as potential MPAs for sickle cell disease. Children with SCD had an under-developed palatal rugae pattern with a deep, narrow and small palate when compared to healthy children.The dimensions of the palatal rugae pattern in SCD showed reduced distance between the incisive papilla and the first and last rugae, indicating a further decrease in the anteroposterior dimensions of the palate. These findings may aid in the early diagnosis and prevention of malocclusion in children with SCD by appropriate interceptive orthodontic treatment.

Are palatal rugae reliable markers for 3D superimposition and forensic human identification after palatal expansion? A systematic review

OBJECTIVES

Palatal rugae are periodic structures situated in the palatal mucosa, often used as landmarks for human identification and superimposition of digital dental models. This review aims to collect the current evidence regarding whether orthodontic palatal expansion could affect the stability of the palatal rugae and to give preliminary guidelines.

MATERIALS AND METHODS

A systematic review of the literature was performed in the scientific databases Pubmed; Embase; WoS; and Cochrane. Grey Literature was also sought (clinicaltrial.gov; ICTRP; AHRQ; INAHTA). The search protocol, was registered in PROSPERO (N*208722). Data extraction comprised: year of publication, journal, sample size, characteristics of the experimental and control group, type of expander, expansion protocol, rugae classification, measurement method on casts, time between casts, method error, rugae change, morphology change and overall outcome. Risk of bias of the included articles was evaluated with the Newcastle-Ottawa Scale.

RESULTS

A total of 12394 manuscripts were retrieved after duplicate removal. From these, nine articles were finally included for data extraction. three studies scored as low risk of bias, two as medium and four as high.

CONCLUSIONS

The morphology of the palatal rugae can be modified by palatal expansion techniques, especially by rapid maxillary expansion. The first rugae is the most stable along with the points close to the palatal midline, which should be used as a reference both for manual or semi-automatic superimpositions. Human identification and serial superimpositions based on palatal rugae should not be carried immediately post expansion and be taken in consideration with caution in patients who underwent prior palatal expansion.

Genetic variants in bone morphogenetic proteins signaling pathway might be involved in palatal rugae phenotype in humans

This study investigated, if genetic variants in BMP2, BMP4 and SMAD6 are associated with variations in the palatal rugae pattern in humans. Dental casts and genomic DNA from 75 patients were evaluated. Each patient was classified as follows: total amount of rugae; bilateral symmetry in the amount, length and shape of the palatal rugae; presence of secondary or fragmentary palatal rugae; presence of unifications; predominant shape; and predominant direction of the palatal rugae. The genetic variants in BMP2 (rs1005464 and rs235768), BMP4 (rs17563) and SMAD6 (rs2119261 and rs3934908) were genotyped. Genotype distribution was compared between palatal rugae patterns using the chi-square test (alpha = 0.05). The allele A was associated with the presence of secondary or fragmentary rugae for rs1005464 (OR = 2.5, 95%CI 1.1–6.3; p = 0.014). Secondary or fragmentary rugae were associated with the G allele in rs17563 (OR = 2.1, 95%CI 1.1–3.9; p = 0.017). rs17563 was also associated with rugae unification (p = 0.017 in the additive model). The predominant shape (wavy) was associated with rs2119261 (p = 0.023 in the additive model). The left–right symmetry of the length of primary rugae was associated with rs3934908 in the recessive model (OR = 3.6, 95%CI 1.2–11.7; p = 0.025). In conclusion, genetic variants in the BMP pathway impacted on palatal rugae pattern.

Oral biosciences: The annual review 2020

BACKGROUND

The Journal of Oral Biosciences is devoted to the advancement and dissemination of fundamental knowledge concerning every aspect of oral biosciences.

HIGHLIGHT

This review featured the review articles in the fields of "Microbiology," "Palate," "Stem Cells," "Mucosal Diseases," "Bone Cell Biology," "MicroRNAs," "TRPV1 Cation Channels," and "Interleukins" in addition to the review article by prize-winners of the "Rising Members Award" ("DKK3 expression and function in head and neck squamous cell carcinoma and other cancers"), presented by the Japanese Association for Oral Biology.

CONCLUSION

These reviews in the Journal of Oral Biosciences have inspired the readers of the journal to broaden their knowledge regarding the various aspects of oral biosciences. The current editorial review introduces these exciting review articles.

Palatal rugae morphology is associated with variation in tooth number

This observational study compared palatal rugae morphology in adolescent subjects with normal tooth number and tooth agenesis. Maxillary dental study casts were used to compare rugae number, length and shape. Each study group contained 60 subjects (30 females and 30 males) mean age 13.4 (SD, 1.55) in control and 13.56 (SD, 1.54) years in tooth agenesis groups (p = 0.576). Mean number of missing tooth units in the tooth agenesis group was 2.1. Mean number of primary rugae in the whole sample was 4.35 (SD, 0.98) on the right and 4.33 (SD, 0.92) on the left with no significant differences (p = 0.236 and p = 0.404, respectively). However, the number of secondary rugae on the left (p = 0.006) and fragmentary rugae on the right (p = 0.004) was significantly increased in the tooth agenesis group. The shape of left primary rugae 2 and 3 also differed between groups, tending towards a wavy pattern in the control group and curved in the tooth agenesis group (p = 0.012 and p = 0.004, respectively). In addition, primary rugae 3 was more convergent (p = 0.008) whilst left primary rugae 3 and 5 were orientated in an antero-posterior direction (p = 0.04 for both rugae) in the tooth agenesis group. Subgroup analysis also identified significant associations between patterns of tooth agenesis and rugae number, in addition to shape of primary rugae. The identification of significant differences in rugae pattern between subjects with normal tooth number and agenesis suggests potential commonality in signal pathway disruption during establishment of these structures.