Attritio dentis

[NewToLatin]

As a dental student I’ve started to take interest to our latin diagnoses. Before I deep dive and learn the proper grammar, I have a few questions I’ve been thinking about:

First diagnosis: ‘Attritio dentis’. My understanding is that ‘attritio’ should be in nominative as it is the subject. Then ‘dens’ in genitive ‘dentis’ as it’s attrition in relation to a tooth. But why is it this way around and not ‘dens attritionis’?

Second diagnosis: ‘Caries dentalis’. Again, Caries in nominative, however, then I don’t understand why ‘dens’ suddenly has to be used as an adjective and becomes ‘dentalis’. Why is it not ‘caries dentis’?

Bonus - third: we diagnose three degrees of caries: caries superficialis/media/profunda. ‘Media’ f nominative of ‘medius’, but when will you opt to use ‘medialis’ instead? I see media/medialis used in different cases in medicine, just not sure when to use what. So basically why ‘caries media’ and not ‘caries medialis’?

Thanks in advance.

 

[Dantius]

But why is it this way around and not ‘dens attritionis’?

For the same reason that we say "attrition of the tooth" and not "tooth of the attrition." The genitive is essentially translated "of [x]."

Why is it not ‘caries dentis’?

Seems pretty arbitrary to me. 'Attritio dentalis' and 'caries dentis' would both be syntactically fine.

'medialis' is not a standard word in Classical Latin, so I don't think there's any particular reason why one would use it over media. Probably just a weird medical convention.

 

[Iacobinus]

mediālis, -e (a medius), is an adjective (and a neutral substantive) given in the Thesaurus Linguæ Latinæ (VIII, p. 524, 2nd col., l. 52), which covers the vocabulary from the sixth century B.C. to around A.D. 600 :
1. mediālis, -e. [a medius. J.B.H.] 1 partitive (cf. s. v. medius p. 584, 24) de media parte totius rei : neutr. sg. pro subst. : SOL. 20, 9 arbor ... cuius -e ... suicino lacrimat. adi. : PS. SOL. add. p. 221, 23 lignum ebeni omne atque -e (medicale A) eadem ferme ... facie eqs. 2 non partitive (cf. s. v. medius p. 582, 11) de tota re in medio aliarum sita : EPIST. praef. praet. ad Orcist. (CIL III 7000) 23 ita ... oppido locus opportunus ... ut ex quattuor partibus eo totidem in sese congruant viae, quibos omnibus publicis mansio ea -is adque accommoda esse dicatur. MART. CAP. 2 ; 114 diadema..., quod maxime -is gemmae lumine praenitebat. 8, 849 diversa spatia sunt caelestis ambitus circulique -is (cf. l. 81). cf. medalia.

Medialis can be the nominative, vocative common singular, the accusative common plural or the genitive singular of all grammatical genders.

The neutral substantive is also given in Gaffiot's Dictionary.

 

[scrabulista]

So why caries media rather than caries medialis?

The instances of medialis I see are the muscles:
rectus medialis
vastus medialis
both of these have a lateralis counterpart.

OP has
caries media contrasted with caries superficialis and caries profunda - the middle in terms of severity of decay rather than the middle of the body. That may not be relevant .
Cinefactus??.