Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT06250114 |
| Other study ID # |
ENDOIMPLUNIBO |
| Secondary ID |
|
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
January 12, 2008 |
| Est. completion date |
July 12, 2023 |
Study information
| Verified date |
January 2024 |
| Source |
University of Bologna |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
Introduction: To evaluate the survival and success rate of premolars with a previous root
canal treatment which underwent to non-surgical retreatment or to extraction and implant
replacement.
Materials and methods: Patients visiting in the Clinical Endodontic Section of the School of
Dentistry (University of Bologna) were eligible for the study. Out of these patients, those
with previously root canal treated premolars fulfilled the inclusion criteria. Teeth were
considered retreatable and restorable (Endo group) or not retreatable and not restorable
(Implant group) on the basis of clinical and radiographical examination. Each patient was
included in an annual recall programme and final evaluation was performed after 8 years.
Clinical parameters were recorded. Differences in baseline characteristics between the two
treatment groups were assessed using logistic regression analysis with clustered standard
errors. Results were expressed for each variable as odds ratios (ORs) of implant
rehabilitation to root canal retreatment with 95% confidence intervals (CIs). Survival and
treatment success for the two study groups were estimated using the Kaplan-Meier method. The
association of treatment group with time to event was assessed using Cox proportional hazard
regression analysis with clustered standard errors to allow for intragroup correlation within
teeth belonging to the same patient. Results were expressed as hazard ratios (HRs) of
experiencing the study event among implants as compared to root canal retreatments with 95%
CIs.
Description:
This historical cohort study evaluated the survival and success rate of first and second
premolars with a previous root canal treatment which underwent secondary root canal treatment
vs. extraction and implant replacement.
The study was planned as a historical cohort of patients followed for 8 years. This work was
written according to Consolidated Standards of Reporting trials guidelines for reporting
clinical trials, and was conducted in full accordance with ethical principles, including the
Declaration of Helsinki. At the time of treatment, an informed consent was signed by each
participant.
Patients treated at our university department from January 2007 to December 2015 were
eligible to be included in the study.
The final evaluation was performed between January 2019 and March 2023 in the University
Department.
The primary consideration for inclusion in the study was that both approaches had a sound
clinical and biological rationale and were acceptable in terms of cost for the patient.
Nevertheless, the final decision was always made by a pool of operators based on their
experience and adherence to evidence-based dentistry and best clinical practices.
The following parameters were considered for the decision-making process of each treatment:
- Structural parameters: residual coronal structure (3 or 4 walls, 1 or 2 walls, 0 walls,
full prosthetic reconstruction); presence of deep carious lesions (yes, no).
- Periodontal parameters: distance between cervical enamel junction and first bone contact
(CEJ-MBL) (≤3 mm, > 3 to < 6 mm, ≥6 mm) (Endodontic parameters: initial PAI (1 or 2, 3
to 5); preoperative post (yes, no).
Non-surgical root canal retreatment was performed in accordance to previously-published
clinical protocols. Detailed information is reported elsewhere. All procedures were made by a
pool of tutors of the endodontic master programme.
In all cases, local anaesthesia and dental dam isolation were performed. A straight-line
access was prepared using a diamond burs mounted on high-speed water-cooled handpieces (W&H,
Burmoos Austria). Gutta-percha solvents were used to soften the obturation core and then an
initial pathway was created with Gates-Glidden burs #3 - #4 (Dentsply Maillefer, Ballaigues,
Swiss) to approximately 5-6 mm depth in the gutta-percha. After the complete removal of the
obturation materials, a manual k file crown-down instrumentation technique was performed.
Working length was established with the aid of an electronic apex locator (Root ZX, Morita,
Tokyo, Japan) and radiographically confirmed.
The irrigation protocol included a total amount of 3.0 mL of 5% NaOCl. In case of root
calcification, each canal was subjected to further irrigation with 3 min of 1.0 mL 17% EDTA
solution.
A warm carrier-based technique (Thermafill, Dentsply DeTrey, Konstanz, Germany) with AH Plus
sealer (AH Plus, Dentsply Dental Trey, Konstanz, Germany) was used to complete the root canal
filling. Filling was repeated immediately when short fillings (<2 mm from the radiological
apex) or presence of voids/unfilled canals was identified on periapical X-rays.
All teeth were restored within 2 to 3 weeks following root obturation. An adhesive 2-mm thick
build-up was applied using a light-cured glass-ionomer cement (Vitrebond, 3M, St.Paul, MN,
USA) followed by the application of phosphoric acid etchant solution for 20-30 s and a
bonding system (Clearfil New Bond or Clearfil Photo Bond, Kuraray Co., Ltd, Osaka, Japan)
applied according to manufacturer's directions and total-etch technique. Photo-curable
composite materials (Clearfil Photo Posterior, Kuraray Co., Ltd, Kyoto, Japan; Z100, 3M) were
applied and photo-cured using a multilayering technique to complete the restoration.
Prosthetic rehabilitations, usually performed 3 to 6 months after root canal retreatment were
performed in a high percentage of cases (46 out of 68 [68%]). All teeth were occlusally
loaded and were not used as abutments for multiple fixed restorations.
Extraction and implant insertion procedures were made according to previously published
clinical protocols.
Different implant insertion timings were performed according to the tooth periapical
pathology and presence of periapical infection. Immediate implant placement was made when no
periapical infection was present at the moment of extraction.
For immediate placement, a 1.2 mm drill was used to prepare the alveolar socket, following
the palatal bony walls as a guide. A series of calibrated drills at 225 rpm were used under
copious irrigation with sterile saline solution. Primary implant stability was obtained by
anchoring the implant in the remaining apical portion of the socket at least 3 mm beyond the
root apex area. Titanium implants were placed to keep the blasted surface at cortical bone
level smooth portion of the neck at soft tissue level. A 1.0 mm cover screw was then
positioned and maintained for all the healing phases.
For early placement, a period of approximately 3 or 6 months was waited. A flapless or a
flapped technique was performed. A 1.2 mm drill was used to mark the position, angle and
depth. The drill passed through the mucosa (transmucosal), cortical bone and cancellous bone
under copious saline irrigation. A series of twist and calibrated drill at 225 rpm was used
and a site of the adequate depth and diameter was created whilst irrigating with sterile
saline solution. A cover screw of 1 mm was then positioned and maintained for all the healing
phases.
Loading procedures were performed 3 months after implant insertion. Briefly, impressions were
taken in customised resin trays with polyether materials (Permadyne and Garant, 3M ESPE, St
Paul, MN, USA). Customised abutments were delivered after 7-15 days and provisional crowns
cemented in the same session. After one month, definitive metal-ceramic rehabilitations were
positioned and fixed with a polycarboxylate powder/liquid cement (Heraeus Kulzer GmbH, Hanau,
Germany).
The periapical radiographs and clinical data were used to classify the final outcome in both
treatments. Each patient was checked during the routine recall visit and inspected by one of
two examiners for coronal/crown integrity, periapical radiographic status (Endo group) and
radiographic bone level stability (Impla group). Radiographs were taken using the paralleling
technique and dental intraoral films (Kodak, Rochester, NY, USA). Exposure time of each
filling was standardised and a film holder was used (Rinn Corp., Elgin, IL, USA).
Radiographic evaluation was performed pre- and post-operatively, every 1-2 years, when the
clinical symptoms or coronal status required a further radiographic inspection, and at the
end-point by one additional examiner blinded to the study. The following periapical X-rays
were analysed by two independent examiners: before the treatment, at the moment of the
treatment (root canal filling or implant insertion), at 4-year and at 8-year follow-up.
Prior to radiographic evaluation, the examiners were calibrated using well-defined
instructions and reference radiographs with various types of periapical lesions. At the
end-point, periapical tissues were classified on the basis of the Periapical Index score
(PAI) as follows:
- Healthy: absence of radiographic signs of periapical lesions (PAI ≤2), and absence of
clinical signs and symptoms including no tenderness to percussion. Healthy teeth
determined the success rate of the study.
- Endodontic lesion: radiological signs of endodontic disease (PAI ≥3) during follow-up.
- Survival rate: number of healthy and endodontic lesion still functional at the end line
of the study.
Complications were assessed and divided as:
- Minor: complications that did not affect the endodontic retreatment outcome and survival
(e.g. prosthetic complications).
- Major: complications that affected the endodontic outcome/healing and required a
reintervention (e.g. persistent periapical lesion).
- Fatal: complications that affected the survival rate of the tooth (e.g. fractures).
The crestal marginal bone and the bone-implant contact were examined to evaluate the marginal
bone level (MBL). MBL was assessed at the mesial and distal implant surfaces by measuring the
distance between the reference point of the implant platform to the most coronal
bone-to-implant contact level using a scale divided into 0.1 mm steps and corrected according
to the known height and width of each implant. Radiographic evaluation was performed in
single-blind by two additional examiners. Before evaluating the radiographs, the examiners
were calibrated by using well-defined instructions and reference radiographs with different
marginal bone level measures.
Survival rate was calculated as the number of implants still functional at the end line of
the study. Success rate was calculated according to traditionally accepted criteria and
included lack of mobility, lack of infection or suppuration, MBL <2.0 mm in the first year,
and <0.2 mm at subsequent years .
Complications were assessed and divided as:
- Minor: complications that did not affect the implant outcome and survival (e.g.
prosthetic complications);
- Major: complications that affected the implant success and required a reintervention
(e.g. severe MBL losses);
- Fatal: complications that affected the survival rate implant (e.g. peri-implantitis).
Numerical variables were summarised as mean ± standard deviation; categorical variables were
summarised as frequencies and percentages. Crude differences in baseline characteristics
between the two treatment groups were assessed by means of simple logistic regression
analysis with clustered standard errors to allow for intragroup correlation within teeth
belonging to the same patient. Results were expressed for each variable as odds ratios (ORs)
of implant rehabilitation to root canal retreatment with 95% confidence intervals (CIs). A
similar approach was used to compare mean decision-making scores, but a linear model was used
in place of a logistic model.
Survival and treatment success for the two study groups were estimated using the Kaplan-Meier
method using the date of surgery as the time origin and treating losses to follow-up as
right-censored data. The association of treatment group with time to event was assessed using
Cox proportional hazard regression analysis with clustered standard errors to allow for
intragroup correlation within teeth belonging to the same patient. Results were expressed as
hazard ratios (HRs) of experiencing the study event among implants as compared to root canal
retreatments with 95% CIs. The proportional-hazards assumption was confirmed after checking
for nonzero slope of scaled Schoenfeld residuals on time.
In a sensitivity analysis, Cox regression was rerun using weights based on
propensity-for-treatment scores in order to fully balance baseline demographic and anatomical
characteristics in the two study groups. Multiple Additive Regression Trees (MART) gradient
boosting was used to estimate the propensity to get one treatment or the other with a set of
explanatory variables including sex, age, tooth location, and tooth type. As a rule of thumb,
the following settings were adopted for regularisation: maximum tree depth of 5 interactions;
maximum of 20,000 iterations; 50% bagging; 0.01 shrinkage factor. Each observation was
weighted by the reciprocal of the probability of receiving the treatment that was actually
received, which is known as inverse probability treatment weighting (IPTW). Weights were
truncated at the 99th percentile.
Mean differences in PAI (for Endo group) and MBL (for Implant group) were estimated with
linear regression analysis with clustered standard errors.
All analyses were carried out using Stata software, version 17. The significance level was
set at 5%, and all tests were two-sided.
