Clinical Trial Details
— Status: Active, not recruiting
Administrative data
| NCT number |
NCT01229995 |
| Other study ID # |
M17719-104 |
| Secondary ID |
|
| Status |
Active, not recruiting |
| Phase |
N/A
|
| First received |
October 27, 2010 |
| Last updated |
October 27, 2010 |
| Start date |
May 2009 |
Study information
| Verified date |
October 2010 |
| Source |
Harvard School of Dental Medicine |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
United States: Institutional Review Board - Harvard Medical School |
| Study type |
Interventional
|
Clinical Trial Summary
CAD/CAM technology has been introduced to the field of implant dentistry in the beginning of
1990's (Priest 2005). Since their introduction, the use of CAD/CAM technology in the
production of dental implant restorations has been rapidly expanding. However, little
evidence is currently present supporting its clinical viability (Henriksson 2003, Canullo
2007).
Therefore, the suggested prospective randomized study includes bone level placed Straumann
implants restored with transmucosal elements and crowns fabricated using either CAD/CAM
"Etkon" technology (Zirconia abutment and ceramic crown) or a conventional technique
(Crossfit titanium abutment and a ceramometal crown).
The aim of this randomized controlled clinical trial is to examine single-tooth implant
restorations in the esthetic zone. An esthetic area is defined as any area that is visible
in the patient's full smile. [3rd ITI consensus conference 2004] The rehabilitations will be
fabricated using two different techniques. Zirconia CAD/CAM (ZCC) implant restorations
(tests) will be compared to Titanium conventionally-fabricated (TCF) implant restorations
(controls) using, reproducible esthetic (objective/subjective) and biologic parameters.
This in vivo study is a randomized study with two groups of 15 patients with one implant
each for a total of 30 patients and 30 implants. The implants will be examined for
successful tissue integration according to the criteria of success (Buser et al. 1990) at
every recall visit.
In addition, the following parameters will be evaluated for each restoration:
- Esthetic: A. Objective: PES/WES Score (Belser et al. 2009) from 1:1 digital photograph,
study casts, and spectrophotometric measurements, and B. Subjective: VAS questionnaire
for patients and VAS questionnaire from experts.
- Biologic (mPI, mB, simplified GI, microbial sample, periapical radiograph for DIB, and
width of keratinized facial mucosa)
Finally, an evaluation of the mechanical, biologic and technical complications will be
performed at every recall visit. Mechanical complications would be defined as those
complications that involve the prosthesis such as abutment screw loosening, fracture of the
veneer material, fracture of the crown framework, abutment screw fractures, and implant
fractures. The category of biologic complications will include those complications that
involve the soft tissues (e.g., fistula, suppuration, bleeding, gingival inflammation, and
soft tissue dehiscence). Technical complications are defined as those related to restorative
components and crowns (e.g. crown emergence profile, abutment and crown fit, screw
loosening, ceramic fracture).
Description:
Introduction
Long-term prospective studies demonstrate a high success rate of Straumann implants in
partially or fully edentulous patients both with early and conventional loading (Salvi et
al. 2004, Lambrecht et al. 2003, Cochran et al. 2002, Weber et al. 2000, Buser et al. 1997).
Before the introduction of CAD/CAM technology to the field of implant dentistry in the
beginning of 1990's (Priest 2005), the available approach for restoring single dental
implants was either with stock or cast custom abutments and a ceramo-metal crowns. In spite
of the satisfactory results that this conventional treatment approach has achieved, several
disadvantages have been recognized. First, non tooth-colored abutments possess the problem
of bluish appearance of overlying tissue in cases of thin gingival biotype (Barclay et al.
1996, Prestipino and Ingber, 1996). Second, with stock abutments ideal emergence profile can
not be achieved (Daftary 1997), a disadvantage that was reduced with the use of custom
abutments. However, custom abutments present other disadvantages including possible
imprecision of fit due to inaccuracies associated with impression, waxing, investing and
casting procedures and the negative effect of the gold alloy on the peri-implant mucosal
barrier as demonstrated by Abrahamsson in 1998 (Abrahamsson et al 1998 ).
The introduction of CAD/CAM technology to implant dentistry was meant to provide higher
quality restorations. Since its introduction, the use of this technology in the production
of implant ceramic frameworks and crowns especially in esthetic regions has been rapidly
expanding because of the promising esthetic, biologic, and mechanical properties. Alumina as
well as Zirconia abutments are characterized by good tissue compatibility (Abrahamsson et
al. 1998). In a study by Barclay et al in 1996 it was found that plaque accumulation scores
for ceramic-coated transmucosal elements were significantly lower than those recorded in
titanium transmucosal elements (Barclay et al. 1996). These results suggest that the further
development of a ceramic implant transmucosal collar may assist plaque control at the soft
tissue-implant interface and may favorably influence the tissues in this region (Barclay et
al. 1996). Other studies documented no significant differences in plaque accumulation and
microbial colonization between titanium and ceramic abutment samples (Andersson et al. 2003,
Rasperini et al. 1998). The bacterial colonization of Zirconia ceramic surfaces was recently
studied in vitro and in vivo (Rimondini et al. 2002). The authors found that, overall,
Zirconia ceramic surfaces developed for implant abutments accumulate fewer bacteria than
commercially pure titanium, and may therefore be considered as a promising material for
abutment manufacturing (Rimondini et al. 2002). A comparison of the recorded superficial
soft tissue responses to titanium and ceramic surfaces of transmucosal elements of implants
revealed no significant differences between both groups (Barclay et al. 1996, Andersson et
al. 2001). Almost no marginal bone loss was recorded, indicating a stable bone situation
both at ceramic and titatium abutments on single-tooth implants (Andersson et al. 2001).
However, it seems to be that the peri-implant soft tissues adjacent to titanium and ceramic
surfaces may differ in features that are not apparent when routine clinical parameters are
used (Barclay et al. 1996).
Because of their specific mechanical properties, all-ceramic restorations demonstrate a
lower fracture resistance than ceramic restorations supported by metal substructures. The
ceramic abutments on implants are more sensitive to fracture and to handling procedures than
the titanium abutments (Andersson et al. 2001). However, advances have been made in the
fabrication of high-strength all-ceramic abutments for anterior implants (Yildirim et al.
2003). The hardness of the Zirconium ceramic also allows it to undergo conventional
prophylaxis with ultrasonic scalers without alteration of its surface quality of abutment
(Marzouk, 1996). Moreover, Zirconia has a flexural strength and fracture toughness almost
twice as high as alumina (Glauser et al. 2004, Yildirim et al. 2003).
Currently very limited number of clinical studies is present supporting the clinical
viability of CAD/CAM ceramic restorations (Henriksson 2003, Canullo 2007) and no reports
were found on the performance of CAD/CAM ceramic implant restorations in comparison to
conventional implant restorations.
Objective:
The aim of this randomized controlled clinical trial is to examine single-tooth implant
abutments and restorations in the esthetic zone. Restorations will be fabricated using two
different techniques. Zirconia CAD/CAM (ZCC) implant abutments and restorations will be
compared to conventional, prefabricated Titanium (TCF) implant abutments and
porcelain-fused-to-metal restorations using reproducible aesthetic (objective/subjective)
and biologic parameters.
Hypothesis:
The hypothesis of this investigation is that ZCC implant abutments/restorations (test group)
will achieve better biologic and esthetic outcomes when compared with TCF types (control
group). The null hypothesis is defined as follows: ZCC implant abutments/restorations and
TCF implant restorations are indistinguishable when biologic and esthetic outcomes are
compared.
Clinical Significance:
CAD/CAM technology has been involved in the fabrication of dental abutments and restoration
for the purpose of improving the biologic and esthetic results. This assumption has been
formulated primarily from subjective interpretations as objective assessments from
randomized controlled trials are sparse at best. This study will be significant for clinical
dentistry in that it will create evidence on the clinical long-term performance of Zirconium
CAD/CAM abutments and ceramic crowns compared to stock titanium abutments and
porcelain-fused-to-metal restorations using subjective and objective evaluation parameters
that will be statistically compared.
Materials and Methods:
Patients with an indication for an implant supported single tooth restoration in the
esthetic zone will be included in the study according to the following criteria:
Inclusion Criteria:
General:
1. Age > 21 years
2. Absence of relevant medical conditions
3. Absence of periodontal diseases
4. The opposing dentition must be natural teeth or fixed (not removable) restorations on
teeth or implants.
5. Availability for 5-year follow-up
Local:
1. One missing tooth in the esthetic zone. An esthetic area is defined as any area that is
visible in the patient's full smile. [3rd ITI consensus conference 2004]
2. Presence of two intact adjacent teeth which are either non-restored or with minor
restorations (small composite restorations)
3. Adequate native bone to achieve primary stability
4. Adequate band of keratinized mucosa (at least 2mm)
5. Full Mouth Plaque Scores (FMPS) and Full Mouth Bleeding Scores (FMBS) < 25 %
Exclusion criteria
General:
1. Heavy smokers (more than 10 cigarettes/day)
2. Presence of conditions requiring chronic prophylactic use of antibiotics
3. Medical conditions requiring prolonged use of steroids.
4. History of radiation therapy to the head or neck or history of chemotherapy.
5. Physical handicaps that would interfere with the ability to perform adequate oral
hygiene.
6. Patients with inadequate oral hygiene.
Local:
1. Adjacent implant
2. Presence of periapical radiolucencies at the adjacent teeth
3. Missing adjacent teeth
4. Local inflammation, including untreated periodontitis.
5. Persistent intraoral infections.
6. Untreated mucosal diseases.
Subject population Patients will be recruited from the patient pool of the Teaching and
Faculty Practice at the Harvard School of Dental Medicine. A 12-month period will be allowed
to enroll the patients in this study. The mean treatment outcome will be compared between
the two randomized patient groups, allowing for detection of the smallest clinically
important differences between these means (TheSealedEnvelope™-
http://www.thesealedenvelope.com/ power.php).
Patient entry (informed consent, patient registration, randomization and blinding) An
informed consent approved by the Harvard Medical School/Harvard School of Dental Medicine
Committee on Human Studies will be obtained for all subjects to be entered in this study.
Its conduct will adhere to the principles outlined by the Office for Research Subject
Protection of the Harvard Medical School / Harvard School of Dental Medicine. Each subject
will be randomly assigned to one of the two treatment options. A random permuted block
approach will be used to allocate patients into one of the treatment groups. A sealed
envelope containing the treatment group (control or test group) will be assigned to each
patient. Subsequently and according to the assigned treatment, a ZCC restoration (test
group) or a TCF ceramo-metal (control group) will be fabricated and delivered to the
clinician.
For subjective evaluation the trial design will be on a double blinding level, which means
that neither patients nor expert clinicians will know which treatment the patients are
randomized to. This can be achieved by concealing allocation information from patients and
by using expert clinicians, who are otherwise not involved in the patients' care, to assess
treatment difficulties and outcomes without knowing their treatment group.
Treatment groups
30 patients will be randomly allocated to control or test group presented in Table (1)
Group (n= 30 patients) Implant Abutment Crown Loading Test group (n=15) ZCC BL Straumann
Etkon Zirconia Cement-retained Etkon Zirconia 6-8 weeks control group (n=15) TCF BL
Straumann Crossfit titanium Cement-retained PFM 6-8 weeks
Evaluation Parameters and time schedule:
Patients will be evaluated for esthetic (objective and subjective parameters) and biologic
parameters as well as the success criteria through out the study period. The baseline
measurements are defined as the measurements taken during the healing period after insertion
of bone level implant.
During the healing period, after insertion of a Straumann Bone Level implant following
standard surgical procedures, patients will use removable provisional prostheses.
The implants will be examined for successful tissue integration according to the criteria of
success (Buser et al. 1990) at every recall.
Criteria of success:
1. Absence of persistent subjective complaints, such as pain, foreign body sensation
and/or dysaesthesia
2. Absence of a recurrent peri-implant infection with suppuration
3. Absence of mobility
4. Absence of a continuous radiolucency around the implant
Esthetic parameters :
Objective parameters
- Standardized intra-oral digital photograph (1:1 magnification) An intra-oral photograph
will be taken, positioning the plane of the camera body parallel to the vestibular face
of the teeth adjacent to the single edentulous gap. (Figure 1)
- Papilla Height: Distance between the mesial and distal papilla and the zenith of the
mid-facial gingival margin of the adjacent teeth The distance from the most coronal
part of the mesial and distal papillae to the zenith of adjacent teeth, will be
measured from study casts and digital photographs. (Figure 2)
- Buccal gingival margin measurement: Distance between the mid-facial gingival margin and
the incisal edge of adjacent teeth The distance from the zenith of adjacent teeth to
the most coronal part of the incisal edge, will be measured from study casts and
digital photographs. This measurement will serve to determine the buccal gingival
recession/growth when compared with further measurements. It will be recorded as "0" at
baseline. (Figure 3)
- Study cast
- Spectrophotometer recording at adjacent teeth. A spectrophotometer (Crystaleye,
Olympus, Japan) will be used to select and digitally record the shade for each adjacent
tooth. The sterilizable adapter of the spectrophotometer's intra-oral camera will be
positioned on the alveolar process over the respective adjacent tooth. Once the
resulting video image of the tooth is centered in an orthoradial way in the measuring
square depicted on the computer screen, the spectrophotometric data will be recorded
three consecutive times for each tooth. This data will be later compared with records
obtained from final crowns by repeating the spectrophotometer measurement over the
control and test group restorations. (Figure 4)
- Buccal periimplant mucosa margin: Distance between mid-facial gingival margin and
incisal edge of the implant restoration At implant crown insertion, the distance from
the zenith of the implant restoration to the most coronal part of the incisal edge will
be measured from study casts and digital photographs. This measurement will serve to
determine the buccal gingival recession/growth when compared with further measurements.
It will be recorded as "0" at the implant crown insertion. (Figure 5)
Subjective parameters:
1. Visual Analogue Scale (VAS) of patient's judgment on:
- At baseline: detriment of his/her esthetic appearance and respective expectations
- At crown insertion:
- Overall treatment satisfaction
- Accomplishment of initial expectations
- At 1, 6 months, 1, 3 and 5 year follow up:
- • Overall treatment satisfaction
- • Impact on self-esteem
- • Functionality
2. Visual Analogue Scale (VAS) of 3 expert clinicians' judgments on the case difficulty
Parameters Follow-up time schedule Baseline At insertion 1 month 6 months 1 year 3 years 5
years
Esthetic:
Objective:
1. 1:1 digital photograph
2. Papilla height
3. Buccal gingival margin
4. Study cast
5. Spectrophotometer
6. Buccal periimplant mucosa margin
Subjective:
1. (VAS) questionnaire for patients
2. (VAS)questionnaire from experts
Biologic parameters
1. mPI Modified plaque index (Mombelli et al. 1987) for evaluation of oral hygiene
standard: 0: No detection of plaque; 1: Plaque only recognized by running a probe
across the smooth marginal surface of the implant; 2: Plaque can be seen by the naked
eye; 3: Abundance of soft material.
2. mBI Modified sulcus bleeding index (mBI) (Mombelli et al. 1987): 0: No bleeding when a
periodontal probe is passed a long the gingival margin adjacent to the implant; 1:
Isolated bleeding spots visible; 2: Blood forms a confluent red line on margin; 3:
Heavy or profuse bleeding.
3. simplified GI Simplified Gingival Index (Apse et al. 1991): 0: Normal mucosa; 1:
Minimal inflammation with color change and minor edema; 2: Moderate inflammation with
redness, edema and glazing; 3: Severe inflammation wit redness, edema, ulceration and
spontaneous bleeding without probing.
4. Microbiological sample Microbial samples from a tooth in the same sextant as the
implant and from the implant healing cap prior to its initial removal at the start of
the restorative procedures will be obtained. Additional samples will be taken at
1month, 6, 12, 36 and 60 months after the insertion of the restoration. The samples
will be analysed for P. gingivalis, T. forsythia (B. forsythus) T..denticola, .F.
nucleatum, P. micra (P. micros) P. nigrescens, P. intermedia, C. rectus, C. gracilis,
E. nodatum and S. constellatus. (Quirynen et al. 2002, Keller et al. 1998, Conrad et
al. 1996). Sample analysis will be performed at the Forsyth Institute, Boston, MA, on a
contractual basis. Samples will be identified only by their number for this purpose. No
patient identifying data will be revealed. The correlation between the periimplant
microflora before and after loading within the same subject as well as potential
differences in quantity and composition of the microflora of ZCC and TCF implant
abutments and restorations will be analysed.
5. Standardized periapical radiograph to assess DIB values. Standardized peri-apical long
cone parallel radiographs of the implant (Harris et al. 2002) will be taken. For
standardization of radiographs, a film holder will be attached to a custom-made bite
splint. This same device will be used during the whole study for radiographic records.
From these radiographs, bone resorption will be measured as distance from the implant
shoulder to first bone-to-implant contact (DIB). (Figure 6)
6. Width of keratinized facial mucosa
Parameters Follow-up Time schedule Baseline Crown Insertion 1 mos 6 mos 1 year 3 years 5
years
Biologic:
1. mPI (modified Plaque Index)
2. mBI (modified sulcus Bleeding Index)
3. simplified GI (Gingival Index)
4. microbiological sample
5. PA (Periapical X-ray for DIB)
6. Width of keratinized facial mucosa
D. Mechanical, Biologic and Technical complications An evaluation of the mechanical,
biologic and technical complications will be performed at every recall visit. Mechanical
complications would be defined as all those complications that involve the prosthesis such
as abutment screw loosening, fracture of the veneer material, fracture of the crown
framework, abutment screw fractures, and implant fractures. The category of biologic
complications will include the complications that involve the soft tissues ex. fistulas,
suppuration, bleeding, gingival inflammation, and soft tissue dehiscence. Technical
complications would be defined as those complications that are related to lab procedures and
fabricating techniques ex. abutment and crown emergence profile, abutment and crown fit.
Complications Follow-up Time Schedule Baseline At insertion 1 mo 6 mos 1 year 3 years 5
years
Mechanical:
1. Abutment screw loosening
2. Fracture of a veneer material
3. Fracture of the crown framework
4. Fractures of abutment screws
5. Fractures implants
Biologic:
1. Fistulas
2. Suppuration
3. Bleeding
4. Gingival inflammation
5. Soft tissue dehiscence
Technical:
1. Abutment emergence profile
2. Crown emergence profile
3. Abutment fit
4. Crown fit
Statistical Analysis: After data collection and completion of the investigation, a one-way
analysis of variance (ANOVA) will be used to compare the mean values of all objective and
subjective parameters. Their variance will be broken down into two components: (a) "between
groups" component (control group vs. test group) at baseline, crown insertion, and each
follow-up period and (b) "within group" component at baseline, crown insertion, and each
follow-up period. A multiple LSD range test (confidence level 95%) will be applied to
determine which means differ statistically from each other.
Timetable June 2009 beginning of the study May 2010 deadline for patients' entry and
allocation August 2010 deadline for data collection of baseline and crown insertion
measurements September 2010 deadline for data collection of 1-month follow up measurements
February 2011 deadline for data collection of 6-month follow up measurements August 2011
deadline for data collection of 12-month follow up measurements August 2012 deadline for
data collection of 24-month follow up measurements August 2013 deadline for data collection
of 36-month follow up measurements August 2014 deadline for data collection of 48th month
follow up measurements August 2015 deadline for data collection of 60th month follow up
measurements February 2016 deadline for final publication of data
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