Christensen 1981.

Methods	Quasi‐randomised controlled trial comparing 1 intervention group (a combination of articulation and oral myofunctional (tongue thrust) therapy) and 1 control group (articulation therapy only). (The date of the study was not reported.)
Participants	10 children (6 boys and 4 girls) aged 5 years 8 months to 6 years 9 months. All participants had "normal hearing as measured by puretone screening tests, normal development as reported by parents, no other known physical or psychological abnormalities, no previous speech or tongue thrust services, willingness of the parents to cooperate and carry out daily home practice sessions, and white middle‐class home environment" (p 161). In addition, "all children...were observed by the investigator to have visually and acoustically distorted /s/ and /z/, 2 or more other dentally or interdentally produced tongue‐tip sounds (although acoustically correct) and interdental tongue positioning on swallows of all 3 swallowing media (liquid, solids and saliva)" (p 162)
Interventions	The 10 participants were randomly assigned to 1 of 2 groups Intervention group (n = 5) A total of 22 × 30‐minute therapy sessions conducted weekly in the first 6 weeks and twice a week in the following 8 weeks Oral myofunctional therapy was administered in the first 6 weeks and in the following 8 weeks; alternating sessions of oral myofunctional therapy and articulation therapy were conducted. The "Hanson's 1977 approach" (Barrett 1978), which employs neuromuscular facilitation techniques, was used for oral myofunctional therapy for treating /s/ and /z/ Control group (n = 5) A total of 22 × 30‐minute therapy sessions conducted weekly in the first 6 weeks and twice a week in the following 8 weeks Articulation therapy was conducted according to the following steps: "(1) auditory identification of correct and incorrect /s/ and /z/; (2) isolated production of both sounds; (3) production of syllables in initial, medial, and final positions; (4) production in words in all positions and in blends; (5) use in short carrier‐phrase sentences (e.g., I see a ___); (6) use in describing pictures; and finally, (7) normal usage in telling stories and in conversation. Each subject was allowed to progress as fast as he or she was able to master correct production at each step in the sequence" (p 162) At the start of the intervention, about 1.5 to 2.5 therapy sessions were devoted to articulation therapy targeting the placement of speech sounds /t/, /d/, /l/ and /n/ for all participants. As stated above, the frequency of therapy sessions was the same for both intervention and control groups. Total therapy time was 11 hours for each participant. All participants "were given weekly home assignments to be completed with the mother's help in brief, daily home practices" (p 162). "Articulation home assignments" and home assignments for oral myofunctional therapy were mentioned, but it was not clear whether the intervention group was given both home assignments and the control group was given only articulation home assignments (p 162)
Outcomes	The following tests were used for pretreatment and post‐treatment assessments of articulation A word repetition test for evaluating tongue‐tip placement during production of /t/, /d/, /l/, /n/, /s/ and /z/ A "clinician‐designed picture articulation test that elicited spontaneous production of 24 s‐words and 8 z‐words with the target phonemes occurring in all positions and of 7 initial s‐blends" (p 162) Goldman‐Fristoe Test of Articulation (first edition) Additional items were used for post‐treatment assessments of articulation "(1) a sentence repetition series, including a sentence loaded with each of the tongue‐tip sounds and devoid of /ð/ and /Ɵ/ phonemes; (2) counting from 50 to 70 and describing zoo and playground pictures to elicit numerous /s/ and /z/ phonemes in conversation" (p 163)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The method used to generate the random sequence was not described
Allocation concealment (selection bias)	Unclear risk	The method used to conceal allocation was not described
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of participants and personnel was not possible
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinding of the outcome assessor was ensured ‐ "pre‐ and post‐treatment test responses were evaluated by two independent observers... Neither judge knew which children were receiving tongue‐thrust services" (p 162)
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants completed the 22 therapy sessions
Selective reporting (reporting bias)	Low risk	The study appears to be free of selective reporting bias
Other bias	Low risk	The study appears to be free of other bias