Table 5 Follow-up studies providing data on implant therapy after more than 15 years

Dierens et al. (2011)

Retrospective

18.4

- Treated between 1987 and 1993

- Availability of peri-apical radiographs

- Availability of original patient file

Branemark

Single crown (SC)

134/166

84/104 (62.7%/62.7%)

- Deceased (4)

- No contact information (9)

- Moved away (11)

- Did not answer phone (2)

- Loss of all original implants (7)

- Unwilling to attend clinical examination (51)

42.4

91.5% (cumulative, contact group)

Frisch et al. (2020)

Retrospective

25.4

- Treated between 1991 and 1996

- Availability of radiographs after ≥ 20 years

Ankylos, Branemark, IMZ, ITI Bonefit

SC, FDP, RDP

62/?

36/? (58.1%/?)

- Deceased or serious disease (24)

- No participation in supportive implant therapy program (SIT) (7)

- No radiographs (1)

- Reason not known (4)

74.6

94.7% (percentage implants lost)

Astrand et al. (2008)

Prospective

20

- Original study cohort

- Edentulous patients in one or two jaws

Branemark

RDP

48/?

27/146 (56.3%/?)

- Deceased (19)

- Age/sickness (8)

61–94 (range)

99.2% (percentage implants lost)

Lekholm et al. (2006)

Retrospective

20

- Treated between 1983 and 1985

- Treated and followed by one surgeon

- Availability of baseline radiographs

Branemark

SC, FDP

27/112

10/43 (37%/38.4%)

- Deceased (6)

- Moved away (3)

- Unwilling to attend follow-up (1)

68

91% (cumulative, including drop out)

Jokstad et al. (2017)

Retrospective

17.5

- Implant treatment before 2002

Branemark

SC, FDP

298/?

177/? (59.4%/?)

- Could not be located (92)

- Deceased (23)

- Moved away (21)

- Age/illness (14)

- Unwilling to attend follow-up (23)

- Loss of original implant(s) (4)

62

94% (percentage implants lost)

Chappuis et al. (2013)

Prospective

20

- Original study cohort

- Partially edentulous patients

Bonefit

FDP

98/145

31/50 (31.6%/34.5%)

- Deceased (11)

- Moved away, age, illness (20)

66.3

89.5% (percentage implants lost)

Bakker et al. (2019)

Prospective

20

- Original study cohorts (Batenburg et al., 1998; Heydenrijk et al., 2002)

- Edentulous patients

- Patient’s age > 60 years at the time of implant placement

Branemark, IMZ, ITI

RDP

53/106

38/76 (71.7%)

- Deceased (33)

- Moved away (5)

85.5

92.5% (percentage implants lost, including drop out)

Deporter et al. (2014)

Prospective

20

-Original study cohort (Deporter et al. 1992)

-Edentulous patients with advanced mandibular resorption

SPS

RDP

52/156

30/103 (57.7%/66%)

-All implants lost within the first 2 years (2)

- Deceased (11)

-Age, Illness (17)

Not specified

73.4% (cumulative, including drop out except the 2 patients with early loss of all implants)

Jacobs et al. (2010)

Prospective

16

-Original study cohort (van Steenberghe et al. 2000)

-Patients with bilateral tooth loss (Kennedy Class 1)

-Treated between 1993 and 1994

Astra, Branemark

FDP

18/95

6/48 (33.3%/50.5%)

-Deceased (1)

-Moved away (3)

-Age (2)

Not specified

97.7%-100% (cumulative success rate, including drop out, range between subgroups)

Jung et al. (2021)

Prospective, comparative

22–24 (mean value not described)

-Original study cohort (Zitzmann et al. 2001)

-Treated from 1994–1996

Branemark, Biomed 3i, IMZ

Fixed, removable

72/265

33/118

(45.8%/44.5%)

-Deceased (23)

-Moved away, illness (10)

75.8

89.3–93.8% (cumulative, range between subgroups)

Donati et al. (2018)

Prospective, comparative

20

-Original study cohort (Wennström et al. 2004)

Astra

FDP

51/148

26/84 (51%/56.8%)

-Deceased (19)

-Moved away, illness (7)

Not specified

87.8% (percentage implants lost)

Our findings

Retrospective

28.3

- Treated between 1981–1995

- Availability of baseline radiographs

IMZ

FDP, RDP

94/199

79/167 (84%/83.9%)

- Deceased (29)

- Unavailable (26)

- Loss of all original implants (13)

- Age/illness (5)

- Moved away (4)

- No up-to-date radiographs (2)

75.3

79.5% (contact group)