Early loading of implants with fixeddental prostheses in edentulousmandibles: 4.5-year clinical resultsfrom a prospective study

Stefanie SchwarzOlaf GabbertAlexander J. HasselMarc SchmitterChristiane SechePeter Rammelsberg

Authors’ affiliations:Stefanie Schwarz, Olaf Gabbert, Alexander J.Hassel, Marc Schmitter, Christiane Seche, PeterRammelsberg, Department of Prosthodontics,University of Heidelberg, Heidelberg, Germany

Correspondence to:Stefanie SchwarzDepartment of ProsthodonticsUniversity of HeidelbergIm Neuenheimer Feld 40069120 HeidelbergGermanyTel.: þ 49 6221/566 052Fax: þ 49 6221/565 371e-mail: stefanie.schwarz@med.uni-heidelberg.de

Key words: early loading, edentulous mandible, fixed dental prosthesis, implants, survival

Abstract

Aim: The purpose of this study was to evaluate the survival and success of early-loaded

implants placed in the intraforaminal area of the edentulous mandible, and the survival of

the implant-supported fixed dental prostheses (FDP).

Material and methods: Thirty-seven patients (18.9% male, mean age 64.5 years) with

edentulous lower jaws were treated with implant-supported FDPs in the mandible. One

hundred and eighty-five screw-type implants were placed in the intraforaminal area of the

symphysis (five implants per patient). Immediately after implant placement, a framework

was fabricated and the FDP was manufactured on the framework. Within 2 weeks, the

implants were rigidly connected and loaded with the implant-retained FDP.

Results: During the 1–8-year observation period (mean 4.5 years), a total of 32 implant-

retained complications occurred. Nineteen implants were lost in 10 patients, resulting in a

cumulative survival of 89.7%. Nine implants in five patients did not osseointegrate.

Although these implants were not removed, because stability within the connective tissue

was acceptable and inflammation was absent, they were recorded as unsuccessful.

Consequently, the cumulative success declined to 84.9%. Four implants in three patients

had clinical signs of periimplantitis (2.2% of all implants). Denture-related complications

included one complete failure, when one FDP had to be removed after the last of five

implants had been replaced. Furthermore, 10 fractures of the framework occurred in six

patients, three FDPs had to be adapted or modified, and the facing of the FDP had to be

repaired 16 times in 11 patients.

Conclusion: Although one-stage early-loaded implants functioned well for most patients

with edentulous mandibles, immediate loading is associated with a larger number of

implant-related complications than in other studies investigating delayed loading. Because

of the substantial prosthetic complications and aftercare, this procedure cannot be

generally recommended.

Patients edentulous in the mandible fre-

quently experience problems with their

dentures. These problems can encompass

lack of stability and lack of retention,

which are associated with reduced chewing

ability (van Waas 1990). Insertion of im-

plants may improve the situation, leading

to better chewing ability and better

oral-health-related quality of life (Meijer

et al. 1999). The implant-based rehabilita-

tion procedure has been well documented

and reviewed, and is a successful treatment

option for edentulous jaws (Gomez-Roman

et al. 1997). The intraforaminal area of the

mandible, in particular, is described as a

preferred region for implant insertion. This

Date:Accepted 6 August 2009

To cite this article:Schwarz S, Gabbert O, Hassel A J, Schmitter M, Seche C,Rammelsberg P. Early loading of implants with fixeddental prostheses in edentulous mandibles: 4.5-yearclinical results from a prospective study.Clin. Oral Impl. Res. 21, 2010; 284–289.doi: 10.1111/j.1600-0501.2009.01843.x

284 c� 2010 John Wiley & Sons A/S

is especially true in cases of long-term

edentulous jaws associated with distinct

atrophy.

In addition to current literature discus-

sions about aspects of the osseointegration,

design, and surface of implants, there is

still much controversy about whether

immediate or early implant loading is

associated with higher failure than con-

ventional loading. Traditional implant

procedures for the lower jaw recommend

a two-stage surgical procedure, total pros-

theses abstention for 2 weeks after surgery,

and a rest period of at least 3 months before

applying load from masticatory forces to

the implants and surrounding bone via the

prostheses (Branemark et al. 1977).

Clinical studies focusing on immediate

loading of mandibular implants document

the high success of this treatment proce-

dure, however (Schnitman et al. 1997;

Tarnow et al. 1997; Chiapasco & Gatti

2003). The first results were published as

early as 1979 by Ledermann, who inserted

four TPS screws into the intraforaminal

region of an edentulous mandible and

placed a functionally loaded, bar-supported

overdenture on the same day as the surgery

(Ledermann 1979). After 12 years of use,

no implant failed and bone–implant con-

tact was approximately 70–80% at the

interface. The author confirmed the valid-

ity of this treatment concept if a minimum

of four implants was inserted into the

interforaminal area of the symphysis and

if these implants were rigidly splinted with

a bar (Ledermann et al. 1998). Uribe et al.

(2005) reported comparable results for im-

mediate loading in a review of articles from

1997 to 2002. The authors concluded that

the outcome of immediate loading is pre-

dictable if preconditions such as initial

stability (�32 N/cm), micro movement

of the implant (o150 mm), and adequate

implant length (410 mm) are fulfilled

(Uribe et al. 2005).

Besides the treatment option of immedi-

ate implant loading, other authors have

examined the early loading mode, which

was defined at the consensus meeting of

the Implants World Congress in Barcelona

in 2002. According to this definition, early

loading describes insertion of dentures

within a few days after surgery, whereas

immediate loading means inserting the

denture on the day of surgery (Aparicio

et al. 2003).

As a result, Raghoebar et al. (2003) con-

ducted a 3-year multicentre study on one-

stage implant surgery and early loading in

the edentulous mandible. A total of 170

implants were placed in 40 patients with

mandibular edentulism and were function-

ally loaded within 6 weeks with overden-

tures (n¼ 30) or fixed prostheses (n¼ 10).

Over the observation period of 3 years, no

implants were lost after the first year of

loading and implant survival was 93% for

both implants and prostheses (fixed or

removable). In 2007, Kawai and Taylor

reviewed the effect of loading time on the

success of mandibular implant overden-

tures and concluded that conventional

loading after a 3-month healing period

had not been proved to be the only accep-

table procedure (Kawai & Taylor 2007).

Sennerby and Gottlow (2008) also re-

viewed the literature on the clinical out-

come of immediate/early loading of dental

implants based on studies published up to

2005. They found six comparative studies

and reported that none of these revealed

any difference in survival or marginal bone

loss after 1–5 years (Sennerby & Gottlow

2008).

Time-saving implantology seems to be

preferred by dental surgeons, not at least to

accommodate patients’ needs – immediate

and early loading eliminate surgery for im-

plant exposure, and the time for prosthetic

rehabilitation is also minimized, and so

physical and financial strains on the pa-

tients are markedly reduced. Clinical trials

have already been conducted to study this

issue, but there are few studies showing

long-term results, especially for edentulous

mandibles restored with fixed dentures.

The objective of this study was, there-

fore, to evaluate the 4.5-year survival and

success of early-loaded implants placed in

the intraforaminal area of the edentulous

mandible. Special focus was placed on im-

plant survival and on prosthetic complica-

tions within a prospective study design.

Material and methods

Participants

The study included patients seeking treat-

ment at the Dental School of the Univer-

sity of Heidelberg. The 37 patients

recruited were long-term edentulous in

the mandible who had experienced

problems with their dentures, for example

lack of retention associated with reduced

chewing ability. Inclusion criteria for the

study were an edentulous mandible, ade-

quate dimensions of the intermentonian

region (vertically and horizontally at least

1 mm of bone around the implant), and

informed consent to the immediate loading

procedure (265/99, Heidelberg). Exclusion

criteria included drug and alcohol abuse,

uncontrolled diabetes, haemophilia, meta-

bolic disorders, and general contraindica-

tions, for example pregnancy at the time of

the planned implant insertion. Occasion-

ally, however, the study clinicians sus-

pected that, for example, alcohol abuse

might have occurred during the study.

These cases remained in the sample so

that the study results would not be over-

estimated. In case of loss of more than two

implants and subsequent reoperation

within the study, the respective patients

were excluded from further participation.

The initial clinical examination included

orienting assessment of alveolar crest mor-

phology by digital palpation, assessment of

mucosal conditions from pathological find-

ings, and assessment of maxillary dental

status. In the maxilla, 26 patients had

complete dentures, five had fixed dentures,

and six had removable partial dentures. All

available re-evaluations of the patients

within 8 years of service (mean 4.5 years)

were analysed (18.9% male, mean age 64.5

years, standard deviation 7.9). During the

first 16 months of observation, eight pa-

tients (21.6%) were lost to follow-up: one

patient had died, four patients were ex-

cluded from further participation in the

study because of reoperation after loss of

two or more implants, and three patients

did not attend the follow-up examination.

After the follow-up period of 3 years, 28

patients (75.7%) still participated and after

5 years 67.6% (25 patients) were still under

evaluation. The four patients were lost to

follow-up because of serious illness or

death (one each) and return of two patients

to their previous dentist.

Surgical procedure

Before surgery, a panoramic X-ray study,

Orthophos Plus, Sirona GmbH, Bensheim,

Germany of the initial situation and a

panoramic X-ray study (Orthophos Plus,

Sirona GmbH) with the drilling template,

to plan the ideal implant positions, were

Schwarz et al �Early-loaded implants

c� 2010 John Wiley & Sons A/S 285 | Clin. Oral Impl. Res. 21, 2010 / 284–289

performed in all cases (Fig. 1). Surgery

started with a triangular incision with a

trajectory over the alveolar crest and inci-

sions in the region of the first bicuspids.

Raising of the mucoperiostal layer was

followed by creation of notches in the

predetermined zones using rounded drills.

The sequence required for preparation of

the bone bed was completed using the

appropriate drills. Placement of five FRIA-

LOC-System implants (transgingival screw

implants, Friadent GmbH, Mannheim,

Germany) using a mechanical threading

drill followed. The torque of each implant

was controlled manually (demand:

50 N cm). The flap was sutured for open

healing of the implants. The choice of

inserted implants depended on bone di-

mensions; three lengths (10, 13, and

15 mm) and two diameters (3.5 and

4 mm) were used in the study.

Prosthetic procedure

All patients participating in this study were

treated with a fixed dental prosthesis

(FDP). Immediately after implant inser-

tion, the imprint posts of the system were

inserted. The open-impression technique

with polyether material (Impregum; 3M

ESPE, Seefeld, Germany) was used. After

removal of the posts, the healing caps were

positioned and a bite recording was taken.

The patients were reminded to abstain

from use of a prosthesis in the mandible

until insertion of the definitive FDP.

Within 24 h the dental technician made

the titanium metal framework of the

FDP. Clinical fitting of the framework

with monitoring of the passive fit was

then performed. Centric relation recording

was performed and middle line measure-

ments were taken. The next clinical step

was fitting of the waxing on the frame-

work. The FDP was inserted within

2 weeks. The FDP had artificial teeth

including the second bicuspid or the first

molars (shortened dental arch), depending

on the position of the most distal implant.

The limit for the cantilever was no more

than 1 cm distal to the most distal implant.

Subsequent to the passive fitting, the oc-

clusal concepts of the canine guidance

(upper jaw with fixed dentures or partial

removable denture) or the bilateral ba-

lanced occlusion (upper jaw with complete

denture) were ground away. The FDP were

rigidly screwed into the implants using a

torque of 14 N cm. An X-ray study was

performed to monitor the fit.

Re-evaluation

All re-evaluations were performed by den-

tists who had not fabricated the FDP, to

avoid the bias of overestimation of the

quality of their own work. The first clinical

procedure to eliminate possible pressure

sores was conducted 1–4 days after inser-

tion of the FDP. At this stage, the occlu-

sion was monitored again and strict

instructions were given on hygiene of the

implants and the FDP. Subsequent recalls

were performed after 3 months, 6 months,

and then at 1-year intervals. All follow-up

examinations included complete unscrew-

ing and clinical inspection of the implants

and the FDP. Loss of implants, implant

mobility, and signs of periimplantitis were

recorded, as also were fractures of the

framework and the facing. The torque

used to screw the FDP into the implants

was increased to 25 N cm. In addition to

the recall intervals, the patients were re-

quested to consult the clinic immediately

after recognition of any complication.

Therefore, it was possible to record the

real failure time.

(a) (b)

(c) (d)

(e) (f)

(g)

Fig. 1. Surgical and prosthetic treatment sequence. (a) Panoramic X-ray for planning. (b) After implant

insertion. (c) Preliminary clinical fitting of the framework. (d) Panoramic X-ray monitoring of the framework.

(e) Framework on the cast. (f) Finished FDP. (g) Intraoral situation.

Schwarz et al �Early-loaded implants

286 | Clin. Oral Impl. Res. 21, 2010 / 284–289 c� 2010 John Wiley & Sons A/S

Statistical procedures

All data were analysed using SPSS 16.0

(SPSS Inc., Chicago, IL, USA). The prob-

ability of survival was estimated using

Kaplan–Meier survival curves. The effects

of age, gender, the dental status of the

maxilla, and the localization of the im-

plants on the survival of the implants

were evaluated by General Estimation

Equation Model (binary logistic). The de-

pendent variable was implant success yes/

no, and the ID of the subjects was intro-

duced as a subject variable to take into

account that one patient had five implants.

Complications of the FDP were also eval-

uated graphically. The probability level for

statistical significance was set at a¼ 0.05.

Results

Implant-related complications

During the observation period of 1–8 years,

95 implants in 19 patients resulted in no

complication. In 18 patients (90 implants)

32 clinically relevant complications were

recorded. Nineteen implants were lost in

10 patients, resulting in a cumulative sur-

vival of 89.7% after 4.5 years. One patient

lost all five implants, two patients lost

three, one patient lost two, and six patients

lost one. Eleven of the lost implants were

removed within the first 3 months and

seven further implants within 10 months.

Nine implants in five patients, five im-

plants in one patient, and one implant in

four patients did not osseointegrate.

Although these implants were not re-

moved, because stability within the con-

nective tissue was acceptable and

inflammation was absent, they were re-

corded as unsuccessful. Consequently, the

cumulative success declined to 84.9% after

4.5 years. Implants inserted into the most

posterior position were lost more fre-

quently than anterior implants [P¼0.028;

odds ratio (OR) 0.42]. Four implants in

three patients showed clinical signs of peri-

implantitis (2.2% of all implants). Implant

loss and implants without osseointegration

were evaluated as no success whereas signs

of periimplantitis were interpreted as com-

plications. Maxillary dental status had a

significant effect on the occurrence of com-

plications (P¼0.014; OR 4.927). The age

and gender of the patients had no statisti-

cally significant effect (Table 1; Fig. 2).

Denture-related complications

During follow-up, a total of 19 patients had

no complications with regard to mandibular

FDP. Except for the FDP that had to be

removed after the last of five implants was

explanted, no FDP was lost, resulting in

FDP survival of 97.3% after 4.5 years. Three

FDP had to be adapted or substantially

modified after loss of two or more implants

and repetition of the surgery. Consequently,

the survival rate of the original FDP declined

to 89.2%. Additionally, 10 fractures of the

titanium metal framework were documen-

ted in six patients (in four patients the

framework broke twice). Sixteen times in

11 patients (three repairs for two patients,

two repairs for one patient), the facing of the

FDP had to be repaired, and once the poster-

ior teeth had to be replaced after 5 years

because of massive abrasion (Table 2).

Discussion

Study weaknesses and strengths

All surgery was performed by one experi-

enced dental surgeon only; this led to high

homogeneity of implant insertion. The

FDP, however, were fabricated by different

dentists. Nevertheless, important working

steps, for example fitting of the framework

or monitoring of vertical and horizontal

relationship measurements, were performed

by one experienced prosthetist. Again, to

achieve homogeneity, only two dental tech-

nicians were involved. The strength of the

study could, furthermore, be seen in the

prospective study design. The number of

patients who fulfilled the inclusion criteria

and yet declined to participate in the study

was not recorded, however. Therefore, no

information is available about the response.

Table 1. General estimation equation (GEE)-Model for the dependent variable occurrenceof implant failure

Parameter Exp (B)

95% Wald-Confidence interval

SignificanceMinimum Maximum

Age 0.968 0.905 1.034 0.335Gender

Men 2.116 0.583 7.68 0.255Women 1 – – –

MaxillaComplete Denture 4.927 1.385 17.533 0.014Fixed/partial denture 1 – – –

LocalizationAnterior 0.42 0.194 0.909 0.028Most distal position 1 – – –

Fig. 2. Effect of denture type in the maxilla on Kaplan–Meier success curves for mandibular implants (no

success was defined as implant loss or no osseointegration).

Table 2. Frequency and type of prostheticcomplications

Variable

Frequency perprosthesis

TotalOnce TwiceThreetimes

Loss 1 – – 1Fracture 2 4 – 10Remake 3 – – 3Chipping 8 1 2 16

Schwarz et al �Early-loaded implants

c� 2010 John Wiley & Sons A/S 287 | Clin. Oral Impl. Res. 21, 2010 / 284–289

Results and comparison with other studies

Extended integration periods and multiple

surgery are a challenge to patient accep-

tance of implant therapy in the treatment

of edentulous jaws. Early loading of oral

implants could potentially overcome these

problems. It is widely accepted that early

loading is a desirable procedure if outcomes

in terms of implant survival and success are

comparable with those of conventional

loading. In recent years, several reviews

have been published on early loading. The

conclusions were that early-loaded im-

plants resulted in no difference in survival

or marginal bone loss after 1–5 years com-

pared with the original two-stage concept

(Sennerby & Gottlow 2008) and that con-

ventional loading after a 3-month healing

period has not been proved to be the only

acceptable procedure (Kawai & Taylor

2007).

Randow and colleagues compared the

one-stage surgical procedure with the ori-

ginal two-stage concept and therefore

inserted 88 Branemark implants in

16 patients (experimental group) and 30

implants of the same kind in 11 patients

(control group). In the first group, the fixed

appliances were connected to the implants

within 20 days of implant installation

whereas the fixed appliances in the control

group were connected approximately

4 months after fixture installation. During

the 18-month observation period, no fix-

ture was lost in either of the two groups.

The implants under study and those in the

reference material were, at all observation

intervals, found to be clinically stable, and

so the authors concluded that it is, at least

on the basis of an 18-month observation

period, possible to successfully load tita-

nium dental implants early after installa-

tion via a permanent fixed rigid cross-arch

supraconstruction in the interforaminal

area of the edentulous mandible (Randow

et al. 1999). These results were substan-

tiated again in 2000 by the presentation of

stable long-term results from the same

study, based on a 5-year observation period

(Ericsson et al. 2000).

With a cumulative survival of 89.7%

and a cumulative success of 84.9% after

4.5 years of follow–up, the results of this

study are inferior to those described above.

The results are more comparable to

Friberg and colleagues, who evaluated the

5-year implant success of smooth-surface

Branemark-System implants when using a

1-stage surgical procedure with early load-

ing in edentulous mandible. One hundred

and seventy implants were placed in be-

tween the mental foramina, of which 120

implants in 30 patients were associated

with overdenture treatment and 50 im-

plants in 10 patients with fixed complete

dentures. Twelve implants failed in six

patients. The cumulative implant survival

rate was 92.9% after both 1 and 5 years of

follow-up. Another three implants were

recorded as mobile but still in function

when individually checked at the 5-year

visit, which resulted in a cumulative suc-

cess rate of 91% (Friberg et al. 2008). In

this study, implants without osseointegra-

tion were also evaluated as unsuccessful.

Nevertheless, they were not explanted be-

cause, although the patients were informed

of the need for explanting, they did not

agree to further surgery, arguing that the

implants were painless and not causing any

problems. Counting implants without os-

seointegration among the absolute compli-

cations might explain the lower success in

the present study.

In 2009, Eliasson et al. evaluated clinical

outcome and patient satisfaction with early

or delayed loading in patients treated with

fixed prostheses, using three different im-

plant systems. One hundred and nine con-

secutively treated patients received 490

implants supporting fixed prostheses. The

prostheses were placed within 2–3 weeks

in 55 patients; 54 patients underwent a

two-stage procedure. All patients had fixed

prostheses at follow-up with a mean ob-

servation time of 3.5 years. Cumulative

survival rates were 92.5% of prostheses

and 94.4% of implants for early loading,

and 98% and 97.9% for delayed loading.

With early loading, significantly more

prostheses (Po0.05) needed adjustment

or replacement (Eliasson et al. 2009).

Although factors affecting the success of

implants could be of a different origin, the

predominant factor affecting the survival of

early-loaded implants is believed to be im-

plant movement during the healing period.

When osseointegration was successful,

long-term results for early-loaded implants

were comparable with those for implants

inserted using the classical two-stage pro-

cedure (Petersson et al. 2001). This could

be interpreted as agreement with our re-

sults. Eleven of the lost implants were

explanted within the first 3 months, and

seven further implants within 10 months.

With the exception of one implant that

had to be removed after nearly 2 years,

no implant was lost in subsequent years.

In this case, however, the patient had

not attended the previous follow-up

examinations.

It was also shown that edentulous max-

illas with complete dentures had a signifi-

cant effect on implant success in this

study. Wearing complete dentures in the

maxilla was associated with greater failure

of implants in the mandible. This result is

supported by the findings of Falk and

colleagues and Lundgren and colleagues,

who observed increasing local closing and

chewing forces bilaterally in the distal

direction for mandibular implant-sup-

ported cross-arch prostheses occluding

with complete dentures. This was ex-

plained by the behaviour of the maxillary

complete denture during function. The

larger anterior resilience of the oral max-

illary mucosa probably causes hinging of

the denture base, thereby transferring more

load to the posterior area (Lundgren et al.

1989; Falk et al. 1990). Duyck et al. (2000)

also assumed that masticatory forces are

better distributed when the prosthesis is

antagonizing natural dentition or a fixed

restoration instead of a removable denture.

They registered maximum axial forces on

distal implants when the upper jaw was

provided with a removable denture,

although with lack of statistical signifi-

cance (Duyck et al. 2000).

With regard to survival of the FDP, it

was found that no FDP was lost for pros-

thetic-related reasons. One FDP was re-

moved after all implants had been

explanted, however, and three FDPs had

to be modified after reoperation, and so the

survival of the original FDP was 89.2%

only. During the 1–8-year observation per-

iod in this study, 19 patients had no com-

plication with regard to the FDP. The most

common complications were veneer or

resin fractures; the facing of the FDP had

to be repaired 16 times in 11 patients.

Fractures of the titanium metal frame

were observed in 16.2% of the patients,

and the framework broke twice in four

patients. The results of this study can be

seen to be in accordance with results from

studies reported in the literature. Ortorp

and Jemt compared 15-year retrospective

Schwarz et al �Early-loaded implants

288 | Clin. Oral Impl. Res. 21, 2010 / 284–289 c� 2010 John Wiley & Sons A/S

data for 72 of 155 implant-supported fixed

prostheses in the edentulous mandible pro-

vided with laser-welded titanium frame-

works (test) with data for gold-alloy

frameworks (control). The cumulative 15-

year survival of the original fixed pros-

theses was 89.2%. The most common

complications for titanium frameworks

within the follow-up of 15 years were resin

or veneer fractures. Fractures of the tita-

nium metal frame were observed in 15.5%

of the patients (Ortorp & Jemt 2008).

Conclusion

The results of this study showed that

one-stage early-loaded implants functioned

well for most patients with edentulous

mandibles. Early loading is, nevertheless,

associated with more implant-related

complications than in studies investigating

delayed loading, resulting in a greater need

for adaptation and modification of the

FDPs. Because of the substantial prosthetic

complications and aftercare, this procedure

cannot be generally recommended.

Acknowledgements: We thank Ian

Davies, copy editor, for language

revision. We also thank FRIADENT

GmbH, Mannheim, Germany, for

financial support.

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