POSTGRESQL - unnested ARRAY values not behaving as expected

Question

I need to unnest this array so I can join it with a list of IDs(integer)

CREATE TABLE studies  
( 
 study_id INTEGER,
 specialties TEXT[]
)
 WITH (
  OIDS=FALSE
);


CREATE TABLE specialties
(
specialty_id INTEGER,
specialty_text TEXT[]
)
 WITH (
  OIDS=FALSE
);

STUDIES DATA

study_id    specialties 
2333    {}
2332    {}
2329    {'1635','1646'}     
2328    {}
2327    {'1643','1695','1696'}  

SPECIALTIES DATA

specialty_id    specialty_text
1635        Nephrology
1643        General Surgery
1646        Nephrology
1692        Internal Medicine
1695        Neurology

Unnesting the array works fine using this query

select study_id, unnest(specialties) as spec_id
from studies
where study_id in (2333,2332,2330,2329)

Results

study_id        spec_id
2329        '1635'
2329        '1646'
2327        '1643'
2327        '1695'
2327        '1696'

I want to then join the below specialties table, to bring in the corresponding specialty text. However I seem to be having issue with the unnested values having single quotes ' wrapped around them.

I tried trim and ltrim

select study_id, trim(both '''' from unnest(specialties)) as spec_id
from studies
where study_id in (2333,2332,2330,2329,2328,2327,2318,2317)

But the results still appear exactly the same, single quotes not removed - any ideas to remove these so i can cast as integer or join with a numeric field?

study_id        spec_id
2329        '1635'
2329        '1646'
2329        '850761'
2329        '877725'
2329        '1664'

UPDATE

added table definitions and @CraigRinger I tried casting the array to integer, no luck

CAST ATTEMPT:

select study_id, unnest(specialties::integer) as spec_id
from studies
where study_id in (2333,2332,2330,2329,2328,2327,2318,2317)

RESULT:

ERROR: cannot cast type text[] to integer
SQL state: 42846

Answer 1

This worked - thanks @pozs for pointing out my trim was incorrect and fixing that allowed me to cast as integer properly

select study_id, trim(both '''' from unnest(specialties))::integer as spec_id
from studies
where study_id in (2333,2332,2330,2329,2328,2327,2318,2317)

results

    study_id       spec_id  
   (integer)      (integer)  
    2329           1635
    2329           1646
    2327           1696
    2327           1643
    2327           1695