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. 2014 Aug 19;2014(8):CD005098. doi: 10.1002/14651858.CD005098.pub3

Liu 2009.

Methods

  • Trial design: single‐centre RCT (parallel group)

  • Location: Department of Orthodontics, School of Stomatology, Tongii University, Shanghai, China

  • Recruitment period: not stated

  • Funding source: not stated

  • Source of participants: patients attending clinic

  • Study duration: not stated

  • Time points at which follow‐up are reported: before and after active orthodontic treatment
Participants

  • 34 participants in total (28 female, 6 male), mean age 20.68 years

  • 17 in mini‐screw implant group: mean age 21.65 years ± 4.49; 3 males, 14 females

  • 17 in the transpalatal arch group: mean age 19.71 years ± 3.06; 3 males, 14 females

  • Inclusion criteria:

  1. bi‐alveolar dental protrusion presenting as Class I or Class II division I malocclusion

  2. no patients less than 18 years old

  3. no previous orthodontic treatment

  4. all 4 first premolars extracted

  5. maximum anchorage required

  6. agree to have mini‐screw implant and transpalatal arch placed

  7. no congenitally missing teeth except for the third molars
Interventions

  • Comparison 1: Mini‐screw implants (Cibei, Ningbo, China)

  1. Self tapping titanium mini‐screw implants

  2. 1.2 mm diameter, 8 mm length

  3. Placed between roots of the maxillary second premolar and first molar

  • Comparison 2: Transpalatal arch
Outcomes

  • Mesial movement of maxillary first molar on superimposed radiographs measured from the start of space closure until the end of space closure

  • Total duration of treatment
Notes  
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Quote: "they were randomly assigned to two groups with the aid of a table of random numbers"
Allocation concealment (selection bias) Unclear risk The method of allocation concealment was not mentioned
Blinding of outcome assessment (detection bias) 
 All outcomes Unclear risk Not addressed
Incomplete outcome data (attrition bias) 
 mesial movement of upper first maxillary molar Low risk All randomised patients were included in the analysis
Selective reporting (reporting bias) Unclear risk

  • Selective reporting of outcomes: insufficient information to permit judgement

  • Selective reporting of data: no suggestion of selective reporting
Other bias Low risk Study appears to be free of other sources of bias