There isnt a tremendous amount a research in this area  Ive found about a dozen references for facial reconstruction and partial glossectomy tongue reduction that seem relevant  I havent found anything about facial reconstruction since   The results are definitely mixed  For facial reconstruction although most parents reported improvement in their childs speech and appearance independent raters could not readily discern improvement  For partial glossectomy surgeons and parents have noted improvement in speech  Independent raters have demonstrated a mixed bag  when shown videos or in facetoface encounters they indicate improvement but not when hearing a tape of speech  The most recent study  stated The partial glossectomy had obviously a positive impact on both place of articulation and manner of articulation  The analyses revealed a tendency towards vowel speech before surgery along with glottal realizations  After surgery the vowel speech and the compensatory articulation patterns had disappeared