Table 2.

Summary of studies analyzing the costs of implant overdentures and other removable prosthodontic treatment options

Study (years)	Setting, currency, follow-up period (months)	Study design	Study description	Outcome reported
van der Wijk et al. (1998)[13]	Netherlands, Dutch guilders and then converted into USD ($1=Dfl1.6); base year 1994,12	RCT	Group 1: (n=89) Each patient received single-bar retained overdenture on 2 permucosal implants (the Branemark system and the IMZ system) Group 2: (n=30) Each patient received transmandibular implants with a superstructure consisted of a triple-bar construction with cantilever extensions Group 3: (n=28) Each patient received conventional CDs after pre-prosthetic surgeries Group 4: (n=89) Each patient received new conventional CDs	Cost and cost analysis
Takanashi et al. (2004)[14]	Canada, Canadian dollar; base year 1999, 12	RCT	IOD group (n=30): In each patient, two root form implants (ITI, Straumann) placed between the mental foramina, followed by retentive anchors and gold matrices in the overdenture along with a maxillary conventional CD CD group (n=30): Each patient received upper and lower CDs	Direct and indirect costs
Stoker et al. (2007)[15]	Netherlands, Euros €; base year 2000, 96	RCT	Subjects (n=110) treated with one-stage ITI dental implants Group 1: (n=32) In each patient, two-implant-retained overdenture retained with ball attachments (2IBA) and Della Bona matrices was placed Group 2: (n=36) In each patient, two-implant-retained overdenture retained with single egg-shaped Dolder bar (2ISB) was placed Group 3: (n=35) In each patient, four-implant-retained overdenture retained with a triple bar (4ITB) was placed	Aftercare and cost analysis
Walton et al. (2009)[16]	Canada, Canadian dollars (1 CAD=1.00 USD, at the time of writing of the article), 12	RCT	Subjects (n=86) were divided into two groups Some (n=42) received single midline implant (ITI, Straumann) with ball attachment for relined conventional dentures Others (n=44) received two implants in mandibular canine regions (ITI, Straumann) with ball attachment for relined conventional dentures	Patient satisfaction, component costs, time and maintenance
Cristache et al. (2014)[17]	Romania, Euro £, 60	RCT	Fully mandibular and fully/partially maxillary edentulous patients (n=69) received two screw-type Straumann implants in the mandibular canine region. They received overdentures with 3 types of attachment systems Group B (ball attachments) (n=23)  Subgroup B1 - Received retentive anchor with gold matrix[14]  Subgroup B2 - Received retentive anchor with titanium matrix)[14] Group M (magnets) (n=23) Group L (locator) (n=23)	Complications, prosthetic success, and costs
Jawad et al. (2017)[21]	England, Pound £, 6	RCT	Group MI (n=22): Two mini-implants (2.1 mm diameter × 10 mm length one-piece implant with a square collar and ball abutment) were placed transmucosally (flapless) in the interforaminal region of the edentulous mandible Group CI (n=22): Two conventional (3 mm diameter × 11 mm length) implants were placed in the interforaminal region of the edentulous mandible. These were placed after raising soft tissue flaps and drilling directly into bone. Ball abutments were placed on the conventional implants in a one-stage surgery approach to mimic the mini-implant attachment system	Function (masticatory efficiency etc.), cost, QoL

RCT: Randomized controlled trial, IOD: Implant overdenture, CDs: Complete dentures, QoL: Quality of life