DEVELOPMENT OF PALATAL RUGAE
REVIEW OF LITERATURE
ANALYSING AND RECORDING PALATAL RUGAE
ADVANTAGES OF PALATOSCOPY
DISADVANTAGES OF PALATOSCOPY
3. Palatal rugae is an anatomic fold or
wrinkled irregular fibrous connective tissue
ridges located in the anterior third of the hard
Palatal rugae was first described by Winslow In
Rugae are the anatomical folds that are located on the
anterior third of palate behind the incisive papillae to
the mesial aspect of the first permanent molarsand
never crossthe midline. They are also known as “Plica
palatine,Plicae palatinae transverse, Rugae
palatinae,”and the study of these patterns is called
4. DEVELOPMENT OF PALATE
PALATE is the tissue that interposes between the oral
and nasal cavity
It develops from two parts :-Primary palate and
DEVELOPMENT OF PALATE is between 5 to 9 weeks of
PRIMARY PALATE:- Fusion of two medial process and
frontonasal process results in formation of primary palate
SECONDARY PALATE:- Formation of secondary
palate commenses at 7 to 8 weeks and completes
around 3 months of the gestation.
5. Three outgrowth appears in the oral cavity:-
2 nasal process and nasal septum
Each palatal process grows downwards first then
upwards after the withdrawal of tongue (7week)
Septum and the two shelves converge and fuse in
The closue of secondary palate proceeds gradually
form the primary palate in posterior direction
Epithelial seam formed by the adhesion of palatine
shelves is lost due to growth of palate and form
7. DEVELOPMENT OF PALATAL RUGAE
The palatal rugae consisting of keratinizedstratified
squamous epithelium and a high density of Merkel
cells,aid in tongue positionduring masticationand
deglutition.They developby the third month of
intrauterine life and maintain their shape due to the
hydrophilicnature of the abundant
glycosaminoglycans presentin them
Initially, the rugal remains burrowed in the
mesenchyme,creating transverse grooves.These
developinto definitive rugae by forming a connective
tissue core coveredby epitheliumthrough epithelial
thickening and mesenchymal condensation.
Subsequently, the overall corrugatedappearance is
formedwhen the placodes protrude towards the oral
9. The first system of classificationwas developed by Goria in 1911 and was
rudimentary.The rugae pattern was categorizedin 2 ways: specifyingthe
number of rugae and specifyingthe extent of the rugal zone relative to the teeth.
Goria further distinguished two types of rugae namely simple or primitive and
By Trobo:Accordingto this classification,palatal rugae was classified
into two groups:
Simple rugae: Where rugae shapes
were well defined and further sub-
classifiedas A, B, C, D, E F.
Compoundrugae: Where rugae
were formed by union of two or
more simple rugae and were
classifiedas type X.
REVIEW OF LITERATURE &
11. According to Lysell: Palatal rugae were
classifieddepending on its length into
Primaryrugae: 5mms or more
Secondary rugae: 3 to 5mm
Fragmentaryrugae: 2 to 3 mm
Rugae smaller than 2mm are
Kapali et al classification:
Depending on the shape, palatal rugae could be
13. Martins dos Santos classification:
Based on the form and position of each palatal rugae, thisclassificationindicatesand characterizes
One initial rugae; the most anterior
one on the right side is represented
by a capital letter;
Several complementary rugae; the
other right rugae are representedby
One subinitial rugae; the most
anterior one on the left side is
representedby a capital letter;
the other left rugae are represented
15. Thomas and Kotze (1983) classification: The rugae pattern
is classifiedbased on their
length, shape, direction and unification, proposedby Lysell
(1955) and later modifiedby Thomas and
16. da Silva classification:In this classification,palatal rugae are divided into two groups: simple,
from 1 to 6 and composed, resulting fromtwo or more simple rugae. They are named
accordingto each rugae number
17. Basauri classification:It distinguishesbetween the principal rugae, which is the more anterior one
(labelled with letters) and the accessory rugae, which concerns all the remainingrugae (labelled with
numbers).The rugogram is elaborated beginning from the right side of the palate
Human identificationis an important aspect of forensicsciences and various methods such as DNA
analysis; fingerprinting and dental comparisons are currently employed.Dental comparisons
mainly utilize the human dentition for identificationpurposes which serves as a vital source of
informationas they are resistantto various external and internal factors.In addition to the
dentition, use of oral and perioral softtissues have also been employedfor forensicinvestigations
especially in the absence of the former.Rugoscopy,or palatal rugae analysis is a vital component
of forensicodontology that is being investigatedfor use in human identification.This technique
has several advantages and sufficientknowledge of types of palatal rugae and the various methods
available for analysis may aid in proper understanding. Hence, this paper provides an overviewof
classificationof palatal rugae, methods of rugae analysis and a note on its applications in forensic
20. ANALYSING AND RECORDING PALATAL RUGAE: There are several ways to analyze palatal rugae.
Intraoral inspection is probablythe most used and also the easiest and the cheapest. However, it can
create difficulties if a future comparative exam is required.Amore detailed and exact study, as well
as the need to preserve evidence may justify oral photography or oral impressions.
or the overlayprint of palatal rugae in a maxillarycast, can be used in order
to performcomparative analysis.By using stereoscopy,one can obtain a three dimensionalimage of
palatal rugae anatomy.
It is based on the analysis of two pictures taken with the same camera, fromtwo different
points, usingspecial equipment.Another technique is the sterophotogrammerywhich, by using a
special device called Traste Marker, allows for an accurate determination of the length and position of
every single palatal rugae However, due to its simplicity, price and reliability, the study of maxillary
dental casts is the most used technique
21. RECORDING PALATAL RUGAE
Mark rugae patterns in definitive maxillary cast using permanent marker (Fig. 1). Block
Rugae marked with permanent marker pen on the cast
Apply auto-polymerizing resin (clear) in sprinkle on method on the rugae portion in the
cast. The markings will be seen through the transparent resin in the cast (Fig. 2). The
thickness of resin added should not exceed 1 mm.
22. Apply auto-polymerizing resin (pink) in sprinkle on method on the rest of cast and fabricate the
record base in the usual manner. Proceed with the tentative jaw relation and teeth arrangement.
Trial denture verification is done.
Demount the maxillary cast from articulator. Cut dental floss (ICPA waxed interdental floss) as
per the required lengths and lute them over the rugae marking seen through the record base using
inlay casting wax (Sigmadent) (Fig. 3). A wax dropper (P.K. Thomas instruments) can be used for
this purpose. The thickness of dental floss used is 0.75 mm. Two or three floss threads can be luted
together for duplicating variations in the thickness of rugae.
Proceed with fabrication of denture in conventional manner The rugae pattern is duplicated in the
23. ADVANTAGESOF PALATOSCOPY:
1. Palatal rugae are used in human identification due to their singularityand unchangeable nature.
Changes that occur fromorthodontic movement, extraction, aging, and palatal expansiondo not
modify the rugae enough to hamper identification
2. Low utilization costs.
3. It is possible to have antemortemdata established such as recordsfound in dental practice in
differentforms(dental casts, old prosthetic maxillarydevices and intraoral photographs) to
compare with post mortem data.
4. Rugoscopyis rather simple technique not requiringany complex instrumentation.
PROBLEMS WITH PALATOSCOPY:
1. Palatoscopymight not be so useful in crime scene investigations in the linking of suspects to
crime scenes. In fact, this kind of evidence is not expected to be found in such circumstances.38
2. Possibilityof rugae pattern forgery.In a case report, Gitto et al. described a method where
palatal rugae were added to a complete denture in order to improve speech patterns in some
patients. This process can lead to false identity exclusion due to misleadingante-mortem data.
24. A double-blind study was conducted on orthodontic casts of patients who underwent orthodontic treatment in
the Department of Orthodontics. The casts were distributed randomly among two observers for
determination of sex and stability of rugae pattern. The two observers were not informed whether the casts
belong to the same patient, and the casts of the pre-operative orthodontic treatment were then matched with
multiple post-treatment casts. The individual observer's analyses were also not disclosed to the other
observer. The selection of cast for the study was on a random basis without informing the observer on what
kind of study was being performed; this could have brought a selection bias for the study.
The present study was conducted at I.T.S. Centre for Dental Studies and Research, Ghaziabad, India. All
individuals of the study belong to the same geographical population from Western Uttar Pradesh. The study
sample consisted of casts of 50 patients, of which 25 were males and 25 were females. From the above
sample, 10 males and 10 females had undergone orthodontic treatment. All the casts were in the age group
of 15-30 years. All casts were of healthy patients free from any diagnosed congenital abnormalities,
inflammation and trauma. All selected casts from the individuals were free of air bubbles or voids,
especially in the anterior one-third of the palate. In patients who had undergone orthodontic treatment,
their pre and post-operative casts were visualized and compared to find the closest match that is required
for the stability of rugae pattern. Rugae patterns on the study models were delineated using pencil under
adequate light and magnification using a hand lens.
25. To achieve stability during analyses, each of the observers randomly took one pre-operative cast of a patient
who underwent orthodontic treatment and this was matched with multiple post-operative casts on the basis
of palatal rugae, and the closest match was selected. Correctness of the match for each examiner was
calculated as the percentage. Sample size was determined by statistically analyzing the data from which
results would be obtained.
The two observers were not informed whether the casts belong to the same patient, and the casts of
the pre-operative orthodontic treatment were then matched with multiple post-treatment casts. The
individual observer's analyses were also not disclosed to the other observer. The selection of cast for
the study was on a random basis without informing the observer on what kind of study was being
performed; this could have brought a selection bias for the study.
26. The results of the study showed that females have slightly more rugae than males. These sex-wise
distribution modes of unification pattern of rugae showed a statistically significant difference.
Diverging pattern was found more commonly in females compared with males, who predominantly
showed converging patterns. This can probably substantiate the increase in rugae pattern in females.
Variables in length and shape of palatal rugae
The overall percentage of correct matches by observers in palatal rugae pattern between the casts of
pre- and post-operative orthodontic patients was 88.6% and 95.7%, respectively, with a mean of
90.2% and median of 90%. The percentage of correct matches for each case was 74.2% and 100%,
respectively, with a mean of 90.32%.
27. SPECTOGRAM ANALYSIS
Speech is essential to human activity as it is an important function of the stomatognathic
system, which uses the oralcavity as a part of the vocal apparatus. The voice is produced in the
larynx with the aid of the vocal cords vibrating due to the expiratory airflow.
The frequency of the fundamental laryngeal tone is dependent on the vocal cord tension, which
then modulated in the resonance cavities and their shape conditioning the vowel formants
The speech articulatory organs include the tongue, palate,alveolar processes, gums, teeth, and
lips. The teeth, alveolus,and palate are static components of speech articulation whereas
tongue, lip, and velum are dynamic components.
Therefore, phonetics must be considered with mechanics and esthetics as the cardinal factors
contributing to the success of the dental prosthesis
28. Complete loss of teeth can cause persistent speech disorders by altering dental articulation areas
that will severely reduce the quality of speech; particularly the alteration of frontal maxillary
morphology leads to impairment of speech production
Removable complete dentures can partly solve this problem. However, they disturb speech
production themselves as they restrict the flexibility of the tongue, narrow the oral cavity, and alter
the articulation areas of the palate and teeth
Dentures should be made to enable the patient to produce voice and speech without
deficiencies. About 25% of patients in clinical dentistry are considered to suffer from temporary or
permanent changes in articulation due to the applicationof removable dentures. Articulatory
errors may be due to denture factors like altered vertical dimension, size, and position of the
teeth, thickness, and contour of the denture base.Accurate approximation of palatal contours of
a maxillary complete denture to a patient’s tongue can improve speech
29. CASE STUDY
Al-Azhar University(ethical approval number 589/2012)
Group I: patients without denture
Group II: patients with upper acrylic denture having polished anterior palatal
without rugae reproduction in usual thickness (2–2.5 mm),
Group III: patients with conventional upper acrylic denture
with rugae reproduction on its polishing surfaces in usual
thickness (2–2.5 mm)
Group IV: patients with metallic upper denture base of minimal thickness
(0.5–1 mm) and direct ragged metallic palatal surface at rugae area, and
Group V:patients with upper denture having palatal rugae constructed
from resilient acrylic resin material with thickness less than
conventional denture (1.5–2 mm).
The dentures in Groups III, IV, and V were made by duplicating the denture
previously constructed to Group II to preserve the same tooth position,
occlusal plane, vertical dimension, and denture base thickness for each
patient. After that, the duplicated denture was used as trial denture as the
rugae reproduction was performed.
30. Spectral analysis has been used to examine the effects of dental prostheses on
speech sound production. With the use of spectral analysis, a sound event can be
split into three dimensions: frequency, amplitude, and chronologic sequence
It is recommended to reproduce the rugae area in complete denture because the
phonetic quality of complete denture with rugae was superior to the conventional denture.
If the denture was too thick in the anterior region, the result would be a faulty /sh/d/z/t/l/
sound. The dentures with metallic base can enhance /s/sh/t/d/ and /z/ sounds. The use of
resilient acrylic to reproduce the rugae in complete denture can enhance /z/l/s/sh/t/ and
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