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Home , Cusp of Carabelli

Romanian Journal of Oral Rehabilitation Vol. 9, No. 1, January - March 2017

STUDY ON TEETH MORPHOLOGY VARIATIONS AMONG GREEK PATIENTS Anca MihaelaVitalariu1, Chrysi-Christina Markomanolaki2, Irina Chonta3, Odette Luca4, Monica Silvia Tatarciuc1, Cristina Gena Dascalu5 1Grigore T. Popa" University of Medicine and Pharmacy Iași, Romania, Faculty of Dentistry, Department of Implantology, Removable Restaurations, Technology 2Dentist, Private practice, Greece 3Dentist, Private practice, Romania 4Gr. T. Popa" University of Medicine and Pharmacy, Iasi, Romania, Faculty of Dental Medicine, Department of Prosthodontics 5Grigore T. Popa" University of Medicine and Pharmacy Iași, Romania, Faculty of Dentistry, Department of Medical Informatics and Biostatistics,

*Corresponding author: Monica Silvia Tatarciuc e-mail: [email protected]

ABSTRACT Purpose The aim of our study was to verify the variety of some , known as having multiple morphological variations: maxillary , maxillary molars, mandibular and molars. Material and Method. For this study we used intraoral images taken in a dental private practice, in Athens (Greece), between July 2014-July 2016. The study group was composed by 239 patients (105 males and 134 females) aged 17 to 52 years. The results were statistically analyzed with SPSS 16.0. Results. We found some expected morphological aspects, as are described in the literature, but there are some findings quite surprising, especially the number of cusps in mandibular premolars and molars. Conclusions The dentist should be aware that the diversity in human body it is found also in the diversity of teeth morphology. Although in dental school he is receiving a large amount of knowledge, he must continue to learn from his own clinical experience, because in real life, the real morphology is more diverse than in textbooks. Key words Teeth morphology variations, number of cusps, of Carabelli

INTRODUCTION well known that no two individuals have an is defined as the study identical dentition. Most of the present data of the development, morphology, function, on tooth morphology are derived from and identity of each of the teeth in the studies of samples of population of human dentitions. Thus, the study of dental European-American ancestry (EAa). anatomy, physiology, and occlusion Because of the immigration process, it is provides one of the basic components of the most likely that future tooth morphology skills needed to practice dentistry. The standards will reflect the significant change practitioner has to have knowledge of the in the ethnic makeup of the population. For morphology, occlusion, esthetics, and example, a shovel-shaped trait is functions of these teeth to undertake an found in a Caucasoid population only rarely appropriate restorative dental treatment [1]. (less than 5%); however, it is one of the Dental varieties and anomalies have characteristics found in patients with Down important significance for clinical syndrome (trisomy 21) and normally in management, their incidence and degree of Chinese and Japanese individuals, expression providing important data for Mongolians, and Eskimos. Statistically then, phylogenic and/or genetic studies. It is not the shovel-shaped trait might be considered enough to know only the ―normal‖ to be abnormal in the Caucasoid population morphology, it is also necessary to accept but not so in the Mongoloid populations. the concept of morphological variability in a The practitioner must be prepared to adjust functional, esthetic, and statistical sense. It is to such morphological variations [2].

68 Romanian Journal of Oral Rehabilitation Vol. 9, No. 1, January - March 2017

The aim of our study was to verify the or orthodontic treatment. The including variety of some permanent teeth, known as criteria for the group were: patient with having multiple morphological variations: sound teeth, unaltered morphology, maxillary lateral incisors, maxillary molars, no prosthodontic treatment, and no absent mandibular premolars and molars, among teeth. Informed consent was taken from all some Greek patients. the patients. The results were statistically MATERIAL AND METHOD analyzed with SPSS 16.0. The final number For this study we used intraoral images of the patients in the group was 239, 105 made on a group of patients, aged 12 to 52 males (43.9%) and 134 females (56.1%). years. The study was conducted in a dentist The patient‘s age ranged between 12 and 52 private practice, in Athens (Greece), years. For the statistical analysis, they were between 07.2014-072016. grouped into four groups, the larger and the The study group was composed by most representative for our study being the patients who addressed to the dentist mainly group 2 (19-30 years), as it is shown in fig.1.

41-52 12-18 31-40 years years years 7.9% 14.6% 24.7% 19-30 years 52.7% Fig.1.Patients distribution by age RESULTS can be straight (fig.2a), but very often is We found some expected morphological curved, because of its rounded incisal angles aspects, as are described in the literature, but (fig.2b). Actually, it is the most rounded there are some quite surprising findings, incisal margin of all incisors. In some especially the number of cusps in patients can be found a pointed form, named mandibular premolars and molars. peg-shaped lateral (fig.2c), due to Maxillary lateral incisors vary in form microdontia in individual teeth. During the more than any other tooth in the mouth odontogenesis period, injury to the except the third . The Incisal margin of developing tooth can lead to these lateral incisor resembles the central incisor, anomalous morphological features [3].

a b c Fig. 2. Incisal ridge of Maxillary Lateral Incisors; a. Straight, b. Rounded, c. Peg lateral

In our study we found that the frequency smaller number of the patients in our group, of the straight incisal margin (52,3%) is comparing with larger researches. very close to that of the rounded incisal In Maxillary first molars a margin (47,3%) among the patients we supplemental cusp, called the cusp/tubercle examined. In addition, the frequency of the of Carabelli, found at the mesiolingual line peg lateral in our research was lower than in angle of maxillary first molars, is quite literature (0.4), probably because of the common in European dentitions. This

69 Romanian Journal of Oral Rehabilitation Vol. 9, No. 1, January - March 2017 morphological trait can be found as a well- This cusp (tubercle) usually serves to developed fifth cusp, or it can grade down to identify the , and has a series of grooves, or depressions, on the been used to distinguish populations. mesial portion of the lingual surface (fig. 3).

Fig. 3. Cusp of Carabelli In our group we found only 29 patients gender, performed with Pearson Chi-Square (12,1%) with no Carabelli cusp. The rest of test, showed very closed results and, for 210 patients showed various shapes and both, were not statistically significant sizes of Carabelli‘s cusp (fig. 4), but (Pearson Chi-Square = 7.472, p > 0.05)(fig. statistical analysis of the correlations 5). between these variations and the patient 21.9% v small 24.7% v small 26.9% 30.5% small 31.0% small 31.3% 13.3% no 12.1% no 11.2% medium 12.4% M 10.0% medium 8.2% F indistinct 10.9% 6.7% indistinct 14.2% big 11.3% 15.2% big 8.2% 0.0% 10.0% 20.0% 30.0% 40.0% 0.0% 10.0% 20.0% 30.0% 40.0% Fig. 4. Carabelli‘s cusp variations in size and Fig. 5. Correlations between Carabelli‘s Cusp shape and the patient gender can show two - Heart-shaped type is similar to a third types of occlusal surface: molar, with a very small distolingual cusp. - Rhomboidal - is the most common Sometimes the distolingual cusp is form, and it looks much like the first molar, completely absent, therefore the second except the rhomboid is more pronounced. In molar has only 3 cusps (fig.6b) this case there are always 4 cusps (fig.6a.)

a b Fig.6.Shapes of Maxillary second molar: a. Rhomboidal (4 cusps). b. Heart (3 cusps) In our study we found the 4 cusps variant in 51 patients (21.3%). Regarding the variant in 188 patients (78.7%) and 3 cusps correlations between the number of cusps

70 Romanian Journal of Oral Rehabilitation Vol. 9, No. 1, January - March 2017 and the patient gender, the results were not significant lower number of patients with statistically significant (p > 0.05). The age over 40 years have 3 cusps (5.3%) situation was the opposite regarding the compared with the other age categories, and correlation with the patients age, in our a significant lower number of patients with group the results of statistical analysis age between 19-30 years have 4 cusps performed with Pearson Chi-Square test (69.0%) compared with the other age being statistically significant (Pearson Chi- categories Square = 15.285, p = 0.002) (fig.7). A .

>40 y 31-40 y 19-30 y <18 y M F 94.7% 1.9% 89.8% 4 cusps 4 cusps 69.0% 85.7% 78.1% 3 cusps 5.3% 62.7% 10.2% 3 cusps 20.0% 31.0% 2 cusps 14.3% 37.3%

0.0% 20.0% 40.0% 60.0% 80.0% 100.0% 0.0% 20.0% 40.0% 60.0% 80.0% 100.0% Fig. 7. Correlations between number of cusps Fig. 8. Correlations between number of cusps and the patient age - Maxillary 2nd molar and the gender - Mandibular 2nd Mandibular second premolar can be (one Buccal and one Lingual cusp) (fig.9b). found in two forms: with 3 cusps (one The difference between these two types is Buccal and two Lingual cusps - the most primarily in the occlusal surface‘s shape common form) (fig.9a) and with 2 cusps

. Fig. 9. Mandibular second premolar. a) 3 cusps type; b) 2 cusps type which concerns the teeth with 2 cusps, In our study we found the biggest where the percentage of female is bigger percentage in 3 cusps type, as well (69,5%, (fig. 8). meaning 166 patients) and we were surprised to find two patients with a 4 cusps second premolar. Regarding the correlations between the Mandibular 2nd premolar Type It is the largest tooth in the lower arch (number of cusps) and the patient gender, and the crown is wider mesiodistally than the difference between females and males buccolingually. The occlusal outline is was statistically significant (Pearson Chi- pentagonal normally due to the five cusps: Square = 10.505, p < 0.05)(fig. 8). A mesiobuccal, distobuccal, mesiolingual, significant bigger number of male patients distolingual and distal. All of them are have 3 cusps (78.1%) than the female functional, although the distal cusp (D) is patients, the situation being reversed in much smaller than the others. Despite its

71 Romanian Journal of Oral Rehabilitation Vol. 9, No. 1, January - March 2017 name, some dental schools group the D cusp buccal cusps, and 2 lingual cusps (fig.10a). with the mesiobuccal and distobuccal cusps, The second type has 2 buccal cusps, 2 as one of the three “buccal” cusps [4]. lingual cusps, and one distinct D cusp From this point of view, the mandibular (fig.10b). 1st molar displays two forms. First type has 3

a b Fig.10. The types of mandibular 1st molar: a. With 3 buccal cusps; b. With 1 distinct D cusp The results of our study on the was represented by another type of 1st morphology of the mandibular first molars molar, with only 4 cusps, 2 Buccal and 2 were a little surprising, because we found Lingual (fig.11a), that is actually the more types of first molars that are classically occlusal morphology of the 2nd mandibular described in textbooks. So, we found the 5 molar, and found in a percent equal with the cusps first molar in both types of type considered normal for the 1st molar (5 distribution, having close percentages: 3 cusps, 3B and 2L). Another surprising Buccal cusps type was found in 70 persons finding was represented by the mandibular (29,3%), while 1D distinct cusp type was 1st molar with 6 cusps, in three different found in 96 persons (40,2%). A big surprise patients (Fig.11b, 12).

a b Fig.11. a. 1st Mandibular molar with 4 cusps, b. 1st Mandibular molar with 6 cusps >40 y 31-40 y 19-30 y <18 y 6 cusps 1.3% 5.3% 6 cusps 1.6% 57.9% 4 cusps 29.3% 30.5% 4 cusps 27.0% 20.0% 15.8% 3B cusps 29.3% 25.4% 3B cusps 34.1% 25.7% 21.1% 44.1% 1 Distal distinct cusp 40.2% 1 Distal distinct cusp 37.3% 54.3% 0.0%10.0%20.0%30.0%40.0%50.0% 0.0% 20.0% 40.0% 60.0% 80.0% Fig. 12. Mandibular 1st molar – Number and Fig. 13. Correlations between the Mandibular distribution of cusps 1st molar Type and AGE Regarding the correlations between the gender, the difference between females and Mandibular 1st molar Type (number of males was not statistically significant (p cusps and their distribution) and the patient >0.05). The situation was different regarding

72 Romanian Journal of Oral Rehabilitation Vol. 9, No. 1, January - March 2017 the correlation with the patients age, in our important study subject with a big role in group the results of statistical analysis anthropological and forensic dentistry performed with Pearson Chi-Square test studies. Considerably less frequent than on being statistically significant (Pearson Chi- the maxillary first molars, literature Square = 16.909, p = 0.050 – fig. 13). The mentions that this cusp can also be found on young patients, under 18 years old, have the the permanent second molar and even in biggest percentage of cases with 1 distal primary second molars [8-11]. In our group distinct cusp (54.3%), significant bigger than we found only 29 patients (12,1%) with no the other age groups, while the patients with Carabelli cusp and only one patient with age over 40 years have the biggest Carabelli‘s Cusp in both maxillary molars. percentage of first molar with 4 cusps Regarding the correlations between the (57.9%). presence, shape and dimensions of the Carabelli‘s Cusp and the patient gender, and DISCUSSIONS age, in our group the results were quite Our study had results sometimes close, and not statistically significant. expected, and sometimes surprising, Regarding the number of cusps in the different from the information we've Maxillary second molars, our study found gathered from dental morphology textbooks. the 4 cusps type in 188 patients (78.7%) and Regarding the shape of the Maxillary 3 cusps type in 51 patients (21.3%). Lateral Incisor incisal ridge, in our study we Analyzing the correlations between the found that the frequency of the straight number of cusps and the patient gender, the margin (52,3%) is very close to that of the results were not statistically significant. The rounded margin (47,3%) among the situation was the opposite regarding the patients we examined. In addition, the correlation with the patients age, in our group frequency of the peg-shaped lateral in our the results of statistical analysis performed research was lower than in literature with Pearson Chi-Square test being (0.4%), probably because of the smaller statistically significant. number of patients in our group. In a meta- The three cusps type is the most analysis published by Hua F in 2013, the common form of Mandibular 2nd prevalence of peg laterals was 1.8%, the premolar. In our study we found the biggest occurrence rates being higher in percentage in this type, as well (69,5%), but Mongoloid (3.1%) than in black (1.5%) and there are authors reporting smaller percentage white (1.3%) patients, in orthodontic (40%)[4]. We were surprised to found two patients (2.7%) than in the general patients with a 4 cusps second premolar. population (1.6%), and in women than men Regarding the correlations between the (1.35 times more), concluding that the Mandibular 2nd premolar Type (number of prevalence of peg-shaped maxillary cusps) and the patient gender, the difference permanent lateral incisors varies by race, between females and males was statistically population type, and sex [5]. In our group significant (p < 0.05) the results were quite close for men and The results of our study regarding the women, the statistical analysis performed morphology of the Mandibular 1st molar with Pearson Chi-Square test showing no were a little surprising, because we found statistically significance. more types of this molar that are classically The Cusp of Carabelli is a landmark described in textbooks. So, we found the 5 found mainly in the permanent maxillary 1st cusps type first molar in both types of molars and it varies from tooth to tooth, but distribution, having close percentages: 3 most specimens show at least a trace of it. Buccal cusps type was found in 70 persons Carabelli's trait is considered a heritable (29,3%) while 1Distal distinct cusp type was feature and development of this trait is found in 96 persons (40,2%). A big surprise affected by multiple genes [6,7]. The wide was represented by a 1st molar with only 4 morphological variations make it an cusps, 2 Buccal and 2 Lingual (which is

73 Romanian Journal of Oral Rehabilitation Vol. 9, No. 1, January - March 2017 actually the typical morphology of the 2nd statistical analysis performed with Pearson mandibular molar), found in our group in a Chi-Square test being statistically percentage equal with the type considered significant. normal for the 1st molar (5 cusps, 3B and 2L). Another surprising finding was CONCLUSIONS represented by the mandibular 1st molar The study of dental anatomy provides with 6 cusps, in three different patients, but the basic component of the skills needed to we found similar data mentioned in the practice dentistry, but it must be understood literature [12]. Regarding the correlations that description in anatomy can never follow between the Mandibular 1st molar type a set in stone rule. Variations frequently (number of cusps and their distribution) and occur, and are of great interest to the dentist the patient gender, the difference between from a practical and scientific point of view. females and males was not statistically Studies on the dental morphology significant (p >0.05). The situation was variations are important in anthropology, different regarding the correlation with the clinical dentistry and Forensic dentistry, as patient age, in our group the results of well.

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