Author Year Country Gender age Aetiology Side and area involved Imaging examinationsa Imaging featuresb
Kang et al. [33] 2015 Korea Case 1: female 80;
Case 2: female 25;
Case 3: female 49;
Case 4: female 19 		Case 1: trauma;
Cases 2,3 and 4: not determined 		Case 1: left, lateral pterygoid muscle;
Case 2,3 and 4: bilateral, pterygoid muscle 		PR, CT, MRI Case 1 PR: no alterations; CT: swelling and loss of fat plane;
Case 2, 3 and 4: PR: no alterations (no CT performed);
MRI: hyperintense T2 signal
Mashiko et al. [34] 2015 Japan Male 36 Trauma Bilateral, masseter CT CT: calcified mass
Torres et al. [35] 2015 Brazil Female 36 Inflammation/
infection (post-exodontia) 		Right, medial pterygoid muscle PR, CT, MRI PR (panoramic radiograph): calcification in mandibular ramus and pterygoid process;
CT: fusion of medial pterygoid muscle to the pterygoid plates;
MRI: calcified mass
Ahmad et al. [36] 2014 Nepal Male 30 Trauma Left, masseter muscle CT Irregularly outlined hyperdense lesion with dense corticated rim
Almeida et al. [37] 2014 USA/
Brazil 		Female 20 Not determined Left, lateral pterygoid muscle CT Calcification of the pterygoid muscle
Boffano et al. [38] 2014 Italy Female 37 Not determined Left, medial pterygoid muscle PR, CT PR (panoramic radiograph): radiopaque calcified region;
CT: irregular heterotopic calcification
Kamalapur et al. [39] 2014 India Female 20 Not determined Left, temporal, lateral and medial pterygoid muscles CT, MRI CT: High attenuation mass (1200 - 1400 HU);
MRI: Hypointense mass on T1
Spinzia et al. [40] 2014 Italy Male 30 Trauma (multiple fractures) Left, lateral pterygoid muscle CT CT: significant calcification of the muscle.
Piombino et al. [41] 2013 Italy Female 62 Not determined Right, masseter muscle PR, CT PR (orthopantomography): radiopaque area in the maxilla;
CT: grossly round mass with heterogeneous density
Choudhary et al. [42] 2012 India Male 31 Trauma Left, medial pterygoid muscle PR, CT PR (mandible lateral oblique): radiopaque mass;
CT: calcification of the muscle
Thangavelu et al. [43] 2011 India Female 36 Trauma (traumatic extraction) Left, medial pterygoid muscle PR, CT PR (panoramic radiograph): elongated left coronoid and radiopaque structures;
CT: irregular ossified mass with multiple foci of central noncalcified regions of low attenuation, surrounded by a peripheral ring of high density, consistent with mature bone
Ramieri et al. [44] 2010 Italy Male 64 Not determined Right, medial pterygoid muscle CT, MRI CT: bone formation within the muscle;
MRI: complete lock of the temporomandibular joint
Trautmann et al. [45] 2010 Brazil Male 33 Inflammation (after mandibular block anaesthesia) Left, medial pterygoid muscle CT Complete calcification of the muscle
Bansal et al. [46] 2009 India Female 20 Trauma (dento-alveolar trauma followed by extractions of all teeth) Right, buccinator and medial pterygoid muscles PR, CT PR (ortopantomography) and CT: calcified mass
Kruse et al. [47] 2009 Switzerland Female 35 After intubation and
chemotheraphy 		Bilateral, masseter muscle PR, CT PR (panoramic radiograph): amorphous calcification within the soft tissue;
CT: bilateral diffuse calcification
Rattan et al. [48] 2008 India Male 45 Injection of absolute alcohol for trigeminal neuralgia Left, medial pterygoid muscles PR, CT PR (orthopantomography): diffuse opacity;
CT: irregular ossified mass
Aoki et al. [49] 2002 Japan Male 44 Trauma (blow on the face) Left, masseter and lateral pterygoid muscles CT, MRI, PET CT: muscle calcification;
MRI: calcified lesions;
PET: spot centered around the masseter muscle
Kim et al. [50] 2002 USA Female 30 Trauma (anaesthesia) Bilateral, lateral pterygoid muscle PR, CT, MRI PR (panoramic radiograph): calcified region;
CT: high attenuation within the lateral pterygoid plate;
MRI: no temporomandibular joint abnormalities
Takahashi and Sato [51] 1999 Japan Female 71 Idiophatic (incidental found) Left, medial pterygoid muscle PR, CT PR (panoramic radiograph): heterotopic calcification;
CT: round masses
Geist et al. [52] 1998 USA Male 44 Trauma (fracture) Left, masseter muscle PR, CT PR (panoramic radiograph and Reverse Towne’s): bone mass in the region of the muscle;
CT: radiopacity
Steiner et al. [53] 1997 USA Male 40/
female 15 		Trauma (fracture)/
trauma (shotgun) 		Left, masseter/
left, masseter muscle 		PR, CT/CT PR (panoramic radiograph): radiopaque mass;
CT: calcified periosteal hematoma within the muscle/CT: calcified mass
Naumann et al. [54] 1993 Germany Male 19 Not determined Right, temporal muscle MRI T2-weighted images showed increased signal intensity within the muscle;
T1-weighted images showed muscle enlarged
Parkash et al. [55] 1992 India Male 28 Not determined Left, medial pterygoid muscle PR, CT PR (panoramic radiograph): obliteration of the temporomandibular joint space and fan-shaped calcified mass;
CT: ossifying lesion, fusion between lateral pterygoid plate and medial surface of mandibular ramus
Fujiwara et al. [56] 1987 Japan Male 63 Not determined Right, buccinator muscle PR, CT PR: no changes;
CT: soft tissue mass without bone destruction
Arima et al. [57] 1984 Japan Male 25 Trauma in the chest which resulted in cheek swelling Left, masseter muscle PR PR: irregular radiopaque mass

aConsidering only preoperative imaging examinations, according to the author's description.
bConsidering exclusively authors description.
PR = plain radiograph; CTBC = cone-beam computed tomography; CT = computed tomography; MRI = magnetic resonance imaging; USG = ultrasound examination; PET = positron emission tomographic scan; HU = Hounsfield unit.