Table 6.
Trait prevalence in the lower primary molars
Merkmalsprävalenz der unteren Milchmolaren
| Trait/Grade | First molars | Second molars | χ2 test | |||||
|---|---|---|---|---|---|---|---|---|
| (laterality) | (dimorphism) | |||||||
| lm1 (r) | lm1(l) | lm2 (r) | lm2 (l) | lm1 | lm2 | lm1 | lm2 | |
| GROOVE PATTERN, n (%) | ||||||||
| Y. Cusps 2 and 3 are in contact | 20 (95.2) | 21 (95.5) | 28 (77.8) | 34 (89.5) | 0.973 | 0.290 | 0.701 | 0.039 |
| +. Cusps 1–4 are in contact | – | – | 4 (11.1) | 3 (7.9) | ||||
| X. Cusps 1 and 4 are in contact | 1 (4.8) | 1 (4.5) | 4 (11.1) | 1 (2.6) | ||||
| HYPOCONULID, n (%) | ||||||||
| 0. Absent | 25 (89.3) | 29 (85.3) | – | – | 0.640 | – | 0.549 | – |
| 1. Present | 3 (10.7) | 5 (14.7) | 57 (100.0) | 63(100.0) | ||||
| CUSP 6, n (%) | ||||||||
| 0. Absent | 28 (100.0) | 34 (100.0) | 57 (100.0) | 62 (98.4) | – | 0.339 | – | 0.275 |
| 2. Cusp 6 smaller than cusp 5 | – | – | – | 1 (1.6) | ||||
| CUSP 7, n (%) | ||||||||
| 0. Absent | 29 (100.0) | 35 (100.0) | 48 (84.2) | 53 (82.8) | – | 0.968 | – | 0.422 |
| 1. Weak short groove of cusp 3 * | – | – | 8 (14.0) | 10 (15.6) | ||||
| 2. Small cusp | – | – | 1 (1.7) | 1 (1.6) | ||||
| PROTOSTYLID, n (%) | ||||||||
| 0. Smooth surface | 31 (96.9) | 36 (97.3) | 29 (49.1) | 31 (48.4) | 0.917 | 0.936 | 0.101 | 0.089 |
| 1. Pit present | 1 (3.1) | 1 (2.7) | 30 (50.9) | 33 (51.6) | ||||
| ANTERIOR FOVEA, n (%) | ||||||||
| 0. Absent | 24 (100.0) | 29 (93.6) | 12 (30.0) | 7 (16.7) | 0.447 | 0.396 | 0.603 | 0.136 |
| 1. Trace with a weak ridge | – | 1 (3.2) | 6 (15.0) | 11 (26.2) | ||||
| 2. Essential ridges on trigonid developed | – | 1 (3.2) | 21 (52.5) | 21 (50.0) | ||||
| 3. Essential ridges pronounced | – | – | 1 (2.5) | 2 (4.8) | ||||
| 4. Well-defined fovea | – | – | – | 1 (2.4) | ||||
| CENTRAL RIDGE OF METACONID, n (%) | ||||||||
| 1. Cusp 2 ridge is similar to the other cusps * | 24 (92.3) | 31(91.2) | 40 (88.9) | 46 (92.0) | 0.875 | 0.605 | 0.065 | 0.934 |
| 2. Ridge is well developed and expands to trigonid *** | 2 (7.7) | 3 (8.8) | 5 (11.1) | 4 (8.0) | ||||
| DISTAL TRIGONID CREST, n (%) | ||||||||
| 0. Absent | 27(93.1) | 31 (91.2) | 35 (94.6) | 35 (92.1) | 0.777 | 0.665 | 0.087 | 0.080 |
| 1. Distal borders are connected by a ridge | 2 (6.9) | 3 (8.8) | 2 (5.4) | 3 (7.9) | ||||
l lower, m molar, 1 first, 2 second, (r) right, and (l) left
*Weak short groove on the lingual ridge of cusp 3
**The essential ridge of the cusp 2 is expressed similar in size and prominence as that of the other cusps
***The essential ridge is very well developed in its thickness on cusp 2 and also expands its width in the trigonid basin