Table 1.
Cephalometric landmarks and their definitions.
List of the anatomical landmarks that were used in this study and their definition, listed in anterior to posterior order.
Table 2.
List of the cephalometric parameters, their abbreviations and definitions.
Parameters are described by distances between two distinct anatomical landmarks, which are defined in Table 1.
Fig 1.
Lateral view of a 3D rendered mandible of a 17 months-old Göttingen Minipig with landmarks and measured parameters.
Where: Con = condylion, Cor = coronion, Sn = lowest point of the sigmoid notch, pCol = posterior point of the mandibular collum, aCol = anterior point of the mandibular collum, Ga1 = horizontal tangent alongside the inferior border of the mandibular body, Ga2 = near vertical tangent alongside the posterior border of the mandibular ramus, Ac = point on the buccal alveolar crest at the vertical level of the posterior mental foramen, Mf = posterior prominent mental foramen, Ib = most inferior point of the mandibular body at the vertical level of the posterior mental foramen, Go = gonion. The parameters measured were: Con–Go = mandibular ramus height (MRH), Cor–Go = oblique mandibular ramus height (oMRH), Dia = diastemal length (DL), Ld = premolar and molar dental arch length (DAL), Mf–Ib = mental foramen to inferior border (MIB), Mf–Ac = mental foramen to alveolar crest (MAC), Mf–Go = mental foramen to gonion (MGO), Ga1-Ga2 = gonial angle (GA), aCol–pCol = mandibular ramus length (MRL), Cor–Con = superior ramus length (SRL), Cpv = coronoid process volume (CPV), Mcv = mandibular condyle volume (MCV).
Fig 2.
Inferior view of a 3D rendered mandible of a 17 months-old Göttingen Minipig with landmarks and measured parameters.
Where: Go = gonion, Me = menton, Id = infradentale. The parameters measured were: Go–Go = intergonial breadth (IGB), Go–Me = inferior mandibular body length (iMBL), Go–Id = mandibular body length (MBL), Me–Id = anterior mentum height (AMH).
Fig 3.
Superior view of a 3D rendered mandible of a 17 months-old Göttingen Minipig with landmarks and measured parameters.
Where: Con = condylion, Cor = coronion, Sn = lowest point of the sigmoid notch, Mf = posterior prominent mental foramen, mDia = midpoint of the diastema, Ac = point on the buccal alveolar crest at the vertical level of the posterior mental foramen. The parameters measured were: mDia–mDia = interdiastemal breadth (IB), Ac–Ac = lingual intercrestal breadth (LIB), Mf–Mf = interforaminal breadth (IFB), Cor–Cor = intercoronoidal breadth (ICOB), Sn–Sn = breadth between sigmoid notches (SNB) and Con–Con = intercondylar breadth (ICB).
Table 3.
Mean values, standard deviations and p-values of all measured parameters.
The data of left and right hemimandibles were statistically similar and were therefore pooled. The p-values presented are the results of the statistical hypothesis tests conducted to determine if the parameter data of the three minipig age groups differ significantly from each other.
Table 4.
Overview of significant changes, lowest and highest individual values and correlations.
Significant correlations are pictured in green, negative correlation in yellow and non-significant values in red. Correlations were considered moderate (0.45 to 0.59), strong (0.60 to 0.79) and very strong (0.80 to 1.0). Significance levels are reported as *p<0.05, **p<0.01, ***p<0.001.
Fig 4.
Box plots of measured parameters.
(A) Box plots of the mandibular ramus height (blue) and oblique mandibular ramus height (red); (B) Box plots of the inferior mandibular body length (blue) and mandibular body length (red); (C) Box plots of the diastemal length (blue) and the premolar and molar dental arch length (red); (D) Box plots of the interdiastemal breadth (blue) and lingual intercrestal breadth (red). Squares associated with the box plots are individual outliers. Outliers marked with asterisks are values that exceed the triple interquartile range.
Fig 5.
Box plots of measured parameters.
(A) Box plots of mental foramen to inferior mandible border height (blue), and mental foramen to mandibular alveolar crest height (red); (B) mental foramen to gonion length (blue) and interforaminal breadth (red). (C) Box plots of the gonial angle measurements (blue); (D) Box plots of the mandibular ramus length (blue) and superior ramus length (red). Squares associated with the box plots are individual outliers. Outliers that are marked with asterisks are values that exceed the triple interquartile range.
Fig 6.
Box plots of measured parameters.
(A) Box plots of the coronoid process volume; (B) Box plots of the mandibular condyle volume; (C) Box plots of the anterior mentum height; (D) Box plots of the intercoronoidal breadth (blue); intercondylar breadth (green); intergonial breadth (orange) and breath between sigmoid notches (red). Squares associated with the box plots are individual outliers.
Table 5.
The total mean values of all parameters measured in each of the three minipig age groups and the corresponding data of humans from the scientific literature. The three different colors identify the differences between the age-group values of the minipigs and the mean values of human data, presented as a minipig/human ratio (MP:H). Ratios lower than 0.85 and higher than 1.15 were defined as substantial anatomical deviations (in red) between the two species where no comparability is present. Parameters with ratios within the range of 0.85 and 1.15 were considered to have a moderate (>0.85 and <1.15 in yellow) or a high (>0.9 and <1.1 in green) comparability.
Fig 7.
Lateral view of the same segmented mandible showing growth changes.
The segmentations show the mandibular volume at 17 (blue) and 21 (green) months of age, merged and presented at the same scale.
Fig 8.
Growth changes of the mandibular condyle and superior ramus.
(A) Posterior view of a mandibular condyle of the same individual animal at 17 (blue) and 21 months (green) of age scaled to same size, showing changes in mandibular condyle volume (MCV) over time. Here: L = lateral aspect of the mandibular condyle and M = medial aspect of the mandibular condyle. (B) Lateral view of the superior area of the mandibular ramus, showing growth changes of the mandibular ramus. Here: Cor = coronion, Con = condylion, aCol = anterior point of the mandibular collum, pCol = posterior point of the mandibular collum. Parameters were: SRL = Cor-Con, MRL = aCol-pCol. Segmentations are presented at the same scale.
Fig 9.
The different morphology of the minipig and human mandible.
3D renderings of an adult human mandible (green) and a mandible of a 21-months old Göttingen Minipig. Both segmentations are presented at the same scale. Where: Con = condylion, Cor = coronion, Sn = lowest point of the sigmoid notch, Go = gonion, Mf = posterior prominent mental foramen, Me = menton, Id = infradentale.
Fig 10.
A 3D-rendered skull of a 12 months-old Göttingen Minipig showing the segmented masticatory muscles.
Where (A) is a lateral, (B) a posterior and (C) a medial view. Pictured are the masseter (green), temporal (blue), medial pterygoid (red) and lateral pterygoid (pink) muscles.
Fig 11.
Vascular architecture medial to the mandibular ramus.
Image (A) is a lateral view of a semitransparent segmentation of a 21 months-old minipig head with associated major blood vessels of the neck and the mandibular region. Arteries are pictured in red and veins in blue. Here: (1) external jugular vein, (2) internal jugular vein, (3) common carotid artery, (4) linguofacial vein, (5) maxillary vein, (6) deep facial vein with maxillary artery, (7) deep facial vein traversing from medial to lateral, (8) lingual artery, (9) buccal artery. Image (B) shows a coronal view with the prominent deep facial vein (6) (in blue), adjacent to the medial aspect of the mandibular ramus (a). The vein has a diameter of approximately 6 mm and traverses from medial to lateral across the anterior aspect of the mandible (7). Here; (a) mandibular ramus, (b) masseter muscle, (c) temporal muscle insertion, (d) lateral pterygoid muscle, (6) deep facial vein, (7) deep facial vein traversing from medial to lateral. Image (C) is a lateral view of a 21 months-old minipig skull with associated large blood vessels of the neck and the mandibular region. Arteries are pictured in red and veins in blue. The green dashed line indicates the most common sectional plane used in experimental mandibular distraction osteogenesis procedures, the black-striped red rectangle indicates a common site for fixation plate placement in some experimental surgery (Fig 12B and 12C).
Fig 12.
Illustration of theoretical space available for mono- and bicortical screw insertion.
Here (A) is an illustration of the human mandibular body (after the AO Foundation, Switzerland), showing the potential space for positioning both mono- and bicortical screws. The pink area indicates a zone, which extends from the tooth roots to the inferior aspect of the mandibular canal that conveys the inferior alveolar nerve and its associated blood vessels. The yellow oval indicates the inferior alveolar nerve. Image (B) is a transverse plane CT image of a 21 months-old minipig head at the level of the first premolar tooth. The area coloured in orange indicates the dimensions of the mandibular canal. Illustration (C) depicts the right mandibular body of the minipig seen in (B), showing one extreme of the highly variable mandibular canal dimensions and the potential space for positioning both mono- and bicortical screws. The pink area indicates a zone where the inferior alveolar nerves and blood vessels are located. Portrayed is the inferior alveolar neurovascular bundle consisting of the inferior alveolar vein (1), the inferior alveolar nerve (2) and the inferior alveolar artery (3).