Palatal Rugae Patterns Research Articles

Disruption of the palatal rugae pattern in Tabby (eda) mutant mice

The eda mouse gene is linked with anomalies of ectodermal derivatives, such as hair, glands, and teeth. The palatal rugae (oral mucosa foldings on the hard palate) are also ectodermal derivatives. Therefore, we searched for and compared palatal rugae anomalies of Tabby mice bearing a mutation in the eda gene with their wild-type counterparts. We compared the number and shape of palatal rugae in 179 mutant and 102 wild-type mice from four different stocks of Tabby mice. Palatal rugae anomalies were documented at a low frequency in wild-type mice of different backgrounds, which may reflect a lack of robustness of palatal rugae development. However, the proportion of anomalies observed in the C57BL/6J background makes us recommend avoiding its use in further palate studies. We showed statistically that the phenotypic variability seen in wild-type animals is further increased in Tabby mutants. The anomalies mainly included various forms of reduction, with rugae IV-VI being more frequently affected. Those rugae were shortened, dotted or absent (mainly ruga V). By analogy to the role played by eda in other ectodermal derivatives, we propose that it might play a role in defining the pattern of the palatal rugae.

Indication and limitations of using palatal rugae for personal identification in edentulous cases

To explore the availability and the limitations of using the palatal rugae pattern in forensic practice for personal identification in edentulous cases, we set up an experiment, which involved 48 patients who had both old and new complete dentures and we observed their rugae. First, we made 48 pairs of maxillary casts from their old and new dentures and a further 50 maxillary casts from complete dentures at random, to use as variables. All the initial impressions taken from the mucosal surfaces of complete dentures were made from alginate impression materials, and the maxillary casts were made from hard dental plaster. Secondly, all 146 casts were trimmed so that all the areas except for the rugae area were removed. Subsequently, 50 examiners were given the 48 casts from the old dentures and were then asked to compare them with the other 98 casts for possible matches. The case numbers, which matched correctly, were recorded. The median percentage of correct matches among the 50 examiners was 94%, despite variations in their experience with forensic identification, and this accuracy does not differ significantly from that in dentate cases, as described in previous publications. The median percentage of correct matches among the 48 cases was 90%. Analyzing the incidence of obtaining a correct match in each case revealed that there were three major misleading shapes that could give rise to a low rate of correct matches; (1) severely low and poorly demarcated eminences of rugae, (2) change of palatal height, and (3) non-complex rugae pattern. These features are mainly due to the shape of the edentulous palate itself and rarely due to the dentures, and could lead to difficulties in finding unique points for use in matching rugae patterns. The results suggest that an appropriate selection of cases, taking into consideration the above misleading shapes, may establish an increased rate of accuracy for identification with this method, thereby bringing the percentage of correct matches closer to 100% in edentulous cases, which is also the percentage of correct matches previously reported in dentate cases.

Palatal ruga anomaly induced by all- trans-retinoic acid in the Crj:SD rat: possible warning sign of teratogenicity

We have reported that the critical period for cleft palate formation by all- trans-retinoic acid (RA) is on gestation day 14 in rats, and classified abnormal patterns of palatal rugae into minor variations and anomalous patterns. In this study, we examined the dose-response relationship for cleft palate and an anomalous pattern of palatal rugae formation and discussed the toxicologic significance of the palatal ruga anomaly as an indicator of teratogenicity. The ED 50 values for cleft palate and anomalous pattern were calculated to be 43.6 and 4.95 mg/kg, respectively. The results clearly show that anomalous rugal patterns occur in the fetuses from litters receiving RA at a lower dose than cleft palate induction; the anomalous ruga pattern is thus more sensitive than cleft palate induction. The anomalies of palatal rugae could be taken as a warning sign or an indicator of teratogenicity of a drug.

Variant Patterns of Palatal Rugae Induced by Chemicals in Mouse Fetuses

AbstractThe oral surface of the mouse palate has eight or nine pairs of transverse ridges, or rugae. We have reported that various teratogens induce abnormal patterns of palatal rugae in mice. In the present note, we show examples of palatal ruga anomalies induced by several teratogens in mouse fetuses near term. Defined variant patterns are supernumerary, division, lateral or medial bifurcation, short, maldirection, cross, modified cross, lateral or medial fusion, lateral or medial bifurcation, median fusion, median division, and numerical reduction. In some cases naming of observed variants may be difficult, but differential diagnosis between variations in the “normal” range and “anomalous” variants seems rather easy.

All- trans-retinoic acid-induced variant patterns of palatal rugae in Crj:SD rat fetuses and their potential as indicators for teratogenicity

We determined the critical period for cleft palate formation in the presence of all- trans-retinoic acid (RA) and defined anomalous patterns within the variants of palatal rugae. The total incidence of variant patterns of palatal rugae in rat fetuses treated with RA at 40 mg/kg on gestation days 13 and 14 dramatically increased with concurrent induction of cleft palate. Correspondence analysis connected the variant patterns of palatal rugae, such as median discontinuity, extra peaks, supernumerary ruga (extra type), shortness, fusion, and bifurcation, with cleft palate. Therefore, these variants were concluded to be anomalous. The incidence of the anomalous patterns of palatal rugae was about 10 times that of cleft palate, and consequently, these anomalies might be sensitive indicators of the teratogenicity of a chemical.

Activities of pharmacologists during defensive war in Bosnia and Herzegovina (toxicological aspect)

The goal of this study is to identify and compare palatal rugae patterns in males and females of an average age of 35 in a sample population from Bosnia and Herzegovina (Sarajevo Canton), as an additional method for sex differentiation in various situations. The research did not determine any statistically significant difference in the total number of palatal rugae between the sexes, which is in line with previous research. However, in the case of the number of secondary palatal rugae where the probability of an equal average is slightly higher than the tolerance of 5%, the difference being 7.6% which may indicate that secondary palatal rugae are more common in women. However, logistic regression analysis LRA is still more successful in classifying males, 69% of them, while for women the success rate is significantly lower with only 41%. In total, 55% of subjects were correctly classified. It may be concluded that using LRA in palatal rugae could be used as an additional sex differentiation method for the population of Bosnia and Herzegovina.

Variations in Palatal Rugae in Near Term Fetuses from Untreated Jcl:ICR Mice

ABSTRACT The oral surface of the mouse palate has eight or nine pairs of transverse ridges, or rugae. Abnormalities in the pattern of palatal rugae have been reported in mutant mice and mice exposed to teratogens in utero. The purpose of this study was to describe control data of ruga variations for proper definition of “anomalous” ruga patterns. Jc1:ICR mice on gestation day 18 were killed, and the fetuses were fixed in Bouin's solution. Fetal palates were examined under a dissecting microscope. In total, 251 fetuses from 19 dams were observed. Among these fetuses 88% had one or more variations in the palatal rugae. Common variations were supernumerary anterior to the fourth ruga, division, and lateral bifurcation, and these were regarded as variations in the “normal” range. Variations rare in fetuses from untreated dams were shortness, fusion, cross, and supernumerary posterior to the fifth ruga, and these should be defined as “anomalous” ruga patterns in teratology experiments. Key words: mouse, palate, rugae, developmental toxicity test

The pattern of palatal rugae in submucous cleft palates and isolated cleft palates

The early diagnosis of submucous cleft palate is important. In children too young to tolerate nasendoscopy and videofluoroscopy the diagnosis depends on the clinical history and intraoral examination. We have studied the pattern of the hard palate rugae to investigate their possible diagnostic significance. Maxillary dental casts were obtained from 16 patients with submucous cleft palate, 17 patients with isolated clefts of the secondary palate, and 10 non-cleft controls. The hard palate mucosa had a unique feature in 14 (87.5%) of the submucous cleft palates: one or more of the palate rugae curved towards the region of the bony notch in the posterior border of the hard palate. The 2 cases without this rugae pattern did not have a detectable bony notch. In 100% of the isolated cleft palate cases, one or more of the rugae curved towards the anterior end of the cleft. This feature was not seen in any of the non-cleft controls. We consider this rugae pattern to be an additional diagnostic feature of submucous cleft palate.