Abstract
Aim
The aim of the present study was to evaluate soft and hard tissue alterations around implants with a modified marginal portion placed in a healed, sloped ridge over 3 years of follow‐up.
Material and Methods
65 patients with a single recipient implant site in an alveolar ridge with a lingual‐buccal sloped configuration were recruited. Implants with a modified geometry in the marginal portion were installed in such a way that the sloped part of the device was located at the buccal and most apical position of the osteotomy preparation. Crowns were placed 21 weeks after implant placement. Radiologic examinations were performed at implant installation and at 1 and 3 years of follow‐up. Bleeding on probing (BoP), probing pocket depth (PPD), and clinical attachment level (CAL; from the crown margin) were recorded at the insertion of the prosthesis and after 1 and 3 years.
Results
57 patients with 57 implant‐supported restorations attended the 3 years follow‐up examination. The radiographic analysis revealed a mean marginal bone loss of 0.57 mm during the 3 years period. While the average bone loss between 1 and 3 years amounted to 0.30 mm, approximately 50% of the implants showed no bone loss during this period. The results from the clinical examinations showed a CAL gain of 0.11 ± 0.85 mm between baseline and 3 years of follow‐up. About 65% of the implants showed no loss of attachment between 1 and 3 years. BoP and PPD ≥5 mm were identified at <10% of implants at the 3 years examination.
Conclusion
Hard and soft tissues formed around dental implants that were designed to match the morphology of an alveolar ridge with a lingual‐buccal sloped configuration remained stable over 3 years.
Keywords: bone, clinical, dental implants, long‐term follow‐up, multicenter study, profile
1. INTRODUCTION
Bone remodeling following tooth extraction frequently results in reduced horizontal dimensions of the alveolar ridge. While data from clinical studies indicated that the bone resorption that occurred following tooth extraction was more pronounced at the buccal than at the lingual part of the ridge (Pietrokovsky & Massler, 1967, Schropp et al., 2003, Huynh‐Ba et al., 2010), the resulting ridge defect often also included a vertical component with a height discrepancy between the buccal and the lingual side of the ridge. The defect morphology in such sites may influence implant installation with the option of reducing the lingual bone component of the defect to achieve a flat contour of the ridge (Carmagnola et al., 1999; Welander et al., 2009). The alternative of preserving the lingual bone component as the crestal bone reference during implant installation, however, will result in an incomplete osseous embracement of the buccal aspect of the marginal portion of the implant. In addition, the lingual part of the ridge may become reduced during healing. The enhanced risk for esthetic complications following such procedures has called for alternative strategies including the use of implants with a modified geometry in the marginal portion, aiming at matching the sloped configuration of the ridge. Data from a preclinical study revealed that healing around such implants placed in a ridge with a sloped lingual‐buccal configuration resulted in the preservation of a vertical discrepancy between the buccal and lingual marginal bone levels (Abrahamsson et al., 2014). In other words, instead of changing the morphology of the recipient site of the alveolar ridge prior to implant installation, the design of the implant may be tailored to match the ridge dimensions. The clinical validity of this concept was evaluated in different prospective multicenter studies over 12–21 months (Noelken et al., 2014; Schiegnitz et al., 2017) and in a study of 13 cases followed for 123 months (Noelken et al., 2021).
The aim of the present clinical study was to evaluate soft and hard tissue alterations around implants with a modified marginal portion placed in a healed, sloped ridge at 3 years of follow‐up.
2. MATERIAL AND METHODS
This prospective multicenter study included 5 centers. The study was registered at ClinicalTrials.gov (NCT00807456) and approved by the 5 local ethics committees. A written informed consent was obtained from all subjects. The study sample comprised 65 subjects between 20 and 74 years of age (mean, 49.1 ± 14.0) with a need for single tooth replacement in a healed ridge with a sloped configuration. Details regarding case selection, surgical and prosthetic procedures were reported previously (Noelken et al., 2014). In brief, patients presenting with a recipient implant site demonstrating a lingual‐buccal bone height discrepancy ranging from 2.0 to 5.0 mm, as assessed by computed tomography (CT) or cone beam computed tomography (CBCT), and with a periodontally healthy adjacent tooth on its mesial aspect were recruited. Implants (OsseoSpeed Profile; Dentsply Sirona Implants, Mölndal, Sweden) with diameters of 4.5 and 5.0 mm and with lengths varying between 9 and 15 mm were installed in such a way that the sloped part of the device was located at the buccal position of the osteotomy preparation. Immediately after implant placement, clinical measurements were performed to evaluate the bone level at the buccal and lingual aspects in relation to the fixed landmark of the implant. The measurements were repeated during a re‐entry surgical procedure after 16 weeks. The prosthetic treatment was completed and the final metal/porcelain prosthetic crown was cemented about 21 weeks after implant placement.
2.1. Clinical and radiologic examination
Clinical parameters such as bleeding on probing (BoP), probing pocket depth (PPD) and clinical attachment level (CAL; from the crown margin) were measured at four aspects of each implant (mesial, buccal, distal, and lingual) at baseline (i.e., prosthesis delivery) and at the 1‐ and 3 years follow‐up. Standardized intra‐oral radiographs were obtained using a parallel technique at baseline (i.e., implant installation), 1 year, and 3 years of follow‐up. The radiographs were analyzed by one experienced radiologist. The borderline between the micro‐ and macro‐threaded portions of the implant was used as a reference point to assess interproximal bone levels. Previous assessments from baseline and 1‐year examinations were re‐calculated to be coherent with 3 years measurements using the current reference point. Examinations were performed with the use of a magnifying lens (x7). All measurements were made to the nearest 0.1 mm. The error inherent in the radiographic assessments was determined and the mean intra‐examiner difference between repeated readings was 0.04 ± 0.33 mm.
2.2. Data analysis
The mesial and distal radiologic bone level assessments were averaged for each implant. Mean values, standard deviations, and frequencies were calculated for data description for each variable at the implant level. Primary outcomes were implant loss and marginal bone level change. A p‐value <.05 was considered to represent a statistical significance. Data were presented in cumulative graphs to illustrate the distribution of observations for each implant/patient regarding clinical and radiological assessments.
3. RESULTS
Of the 65 subjects originally enrolled in the study, 64 attended the 1‐year follow‐up examination. Seven subjects, for unknown reasons, did not attend the 3 years follow‐up examination. Hence, 57 subjects with 57 single implant‐born restorations were available for evaluation after 3 years in function (Table 1). During the period between the 1 year and 3 years follow‐up examinations, two crowns and one abutment lost retention. No implants were lost during the course of the study.
TABLE 1.
Number of patients/implants at the various examination intervals
| No. of patients/implants | Reason for loss of implants to follow‐up | ||
|---|---|---|---|
| Explanted | Drop‐out | ||
| Implant placement | 65 | ||
| Crown placement | 65 | ||
| 1 years | 64 | 1 | |
| 2 years | 59 | 5 | |
| 3 years | 57 | 2 | |
3.1. Radiologic bone level change
The results from bone level measurements are presented in Table 2. The mean bone loss from baseline to 1 year and from 1 to 3 years of follow‐up amounted to 0.29 ± 1.10 mm and 0.30 ± 1.28 mm, respectively. The total amount of bone loss from baseline to the 3 years examination was 0.57 ± 1.60 mm. Figure 1 describes the cumulative percentage of implants according to bone level changes from baseline to 1 and 3 years. For both periods about 80% of the implants showed ≤1 mm of bone loss, and almost 35% of the implants showed no bone loss. Three implants (5.2%) experienced bone loss between 4.4 and 4.8 mm during the 3 years period. The cumulative graph in Figure 2 illustrates bone level changes that occurred between 1 and 3 years of follow‐up. Approximately 50% of the implants showed no bone loss after the 1 year follow‐up, while about 80% of the sample showed ≤0.5 mm of bone loss during the same period.
TABLE 2.
Mean bone level changes (SD) at implant level from baseline to 1 and 3 years based on radiographs available at each follow‐up
| n | Bone level change | |
|---|---|---|
| Baseline—1 year | 55 | −0.29 (±1.10) |
| Baseline—3 years | 52 | −0.57 (±1.60) |
| 1–3 years | 53 | −0.30 (±1.28) |
Abbreviations: Baseline, implant placement; Negative value, bone loss.
FIGURE 1.
Cumulative graph illustrating radiographic interproximal bone level changes between implant placement and 1 years follow‐up and 3 years follow‐up
FIGURE 2.
Cumulative graph illustrating radiographic interproximal bone level changes between 1 years follow‐up and 3 years follow‐up
3.2. Clinical assessments
The results from the clinical measurements are reported in Table 3. The mean changes in the clinical attachment level (CAL) from baseline to 1 year and from 1 to 3 years of follow‐up amounted to 0.02 ± 0.54 mm and 0.08 ± 0.69 mm, respectively. Thus, a CAL gain of 0.11 ± 0.85 mm was observed between baseline and 3 years of follow‐up. Table 4 describes the CAL changes grouped according to the four implant aspects (i.e., mesial, buccal, distal, and lingual). Small changes occurred during the two periods (baseline/1‐year and 1‐year/3‐year). Figure 3 describes the cumulative percentage of implants with CAL gain or loss from baseline to 1 and 3 years. About 65% of the implants showed no loss of attachment during the 3 years of follow‐up. Figure 4 illustrates the cumulative frequency of the CAL change that occurred between 1 year and 3 years of follow‐up. About 30% of the cases demonstrated <1 mm CAL loss while 2 cases (3.5%) presented 2 mm CAL loss. Clinical conditions of the peri‐implant mucosa observed at the 3 years follow‐up examination are reported in Table 5. The peri‐implant mucosa at the majority of the implants at 3 years showed an absence of bleeding on probing (BoP) and had a probing pocket depth (PPD) of ≤4 mm. Five implants (8.8%) exhibited BoP and PPD ≥5 mm. Figure 5 and Figure 6
TABLE 3.
Mean clinical attachment level changes (SD) of all implants evaluated from baseline (i.e., prosthesis delivery) to 1‐ and 3 years and between 1‐ and 3 years follow‐up
| n | Clinical attachment level | |
|---|---|---|
| Baseline—1 year | 63 | 0.02 ± 0.54 (0.0) |
| Baseline—3 years | 57 | 0.11 ± 0.85 (0.0) |
| 1–3‐year | 56 | 0.08 ± 0.69 (0.0) |
Note: Mean ± SD, median.
TABLE 4.
Mean clinical attachment level changes calculated for each implant aspect (i.e., mesial, buccal, distal, and lingual) from baseline (i.e., prosthesis delivery) to 1 year and from 1‐ to 3 years follow‐up
| Mesial | Buccal | Distal | Lingual | |
|---|---|---|---|---|
| Baseline—1 year (n = 63) | 0.0 ± 0.9 (0.0) | −0.1 ± 0.8 (0.0) | 0.1 ± 0.7 (0.0) | 0.1 ± 0.5 (0.0) |
| 1 year to 3 years (n = 56) | 0.0 ± 0.9 (0.0) | 0.1 ± 0.7 (0.0) | 0.0 ± 0.9 (0.0) | 0.3 ± 1.0 (0.0) |
Note: Mean values ± standard deviation (median).
Negative values are loss of attachment.
FIGURE 3.
Cumulative graph illustrating the average clinical attachment level changes between prosthesis delivery and 1 years follow‐up and 3 years follow‐up
FIGURE 4.
Cumulative graph illustrating the average clinical attachment level changes between 1 year follow‐up and 3 years follow‐up
TABLE 5.
Clinical conditions of the peri‐implant mucosa of the implants at 1 and 3 years (implant level); number (frequency %) distribution
| n | BoP+ | PPD ≥5 mm* | BoP‐positive + PPD ≥5 mm | |
|---|---|---|---|---|
| 1 year | 63 | 20 (31.7%) | 4 (6.3%) | 4 (6.3%) |
| 3 years | 57 | 21 (36.8%) | 6 (10.5%) | 5 (8.8%) |
Note: The number indicates that at least 1 side had a PPD ≥5 mm.
PPD values measured as 4.5 mm were round off to 5 mm.
PPD was measured on 4 sides: mesial, distal, buccal, and lingual.
FIGURE 5.
Clinical illustration of case n. 0410 at 1 year follow‐up
FIGURE 6.
Clinical illustration of case n. 0410 at 3 years follow‐up
4. DISCUSSION
In the present multicenter prospective observational study soft and hard tissue alterations around implants placed in a healed, sloped ridge was evaluated over 3 years. It was demonstrated that a mean marginal bone loss of 0.57 mm occurred during the 3 years period. While the average bone loss between 1 and 3 years amounted to 0.30 mm, about 50% of the implants showed no bone loss during this period. The results from the clinical examinations showed a CAL gain of 0.11 ± 0.85 mm between baseline and 3 years of follow‐up. About 65% of the implants showed no loss of attachment between 1 and 3 years. BoP and PPD ≥5 mm were identified at <10% of implants at the 3 years examination.
Few studies have reported data on implants designed to match a sloped contour of the alveolar ridge. Schiegnitz et al. (2017) in a study on 238 implants placed in the posterior mandible of 184 patients, reported that bone loss of 0.30 mm occurred during a follow‐up period of about 21 months. This finding is partly in accordance with data reported in the present study. Although a similar type of implant was used in the study by Schiegnitz et al. (2017) as in the present study, the follow‐up time in the study referred to was shorter. Furthermore, in about 30% of the cases in the study by Schiegnitz et al. (2017) a grafting procedure was performed concomitant with implant installation. No grafting procedures were carried out in the present investigation. Noelken et al. (2016), who also used similar types of implants as in the present investigation, evaluated the healing following immediate installation and immediate restorative procedures in 16 patients. Autogenous bone grafts were used to fill the gap between the implants and the inner walls of the sockets. It was reported that the mean marginal bone loss after 1 and 3 years of function was 0.1 mm and 0.2 mm, respectively. Similar results were reported in a 2 years observational study by Lee and Siu (2016).
The limited scientific evidence on the long‐term follow‐up of implants designed to match a sloped contour of the alveolar ridge justifies comparisons with results from evaluations of regular implants with a flat marginal portion. Thus, in a prospective study on implants used for single tooth replacement, an average bone loss of 0.30 mm after 1 year of follow‐up was reported (Donati et al., 2015). In addition, between 1 and 5 years of follow‐up, 90% of the implants demonstrated no or bone loss ≤0.5 mm bone loss. This observation is in line with data reported in the present investigation. Thus, in the period between 1 and 3 years of follow‐up, 80% of the implants showed no bone loss or ≤0.5 mm bone loss. High proportions of cases showing bone loss <1 mm around implants used in single tooth replacement after 3–5 years of follow‐up were also reported in observational studies by De Bruyn et al. (2013) and Cooper et al. (2021).
In addition to marginal bone level changes, alterations in the clinical attachment level (CAL) were reported in the present study. While an average gain of 0.11 mm was observed for the entire follow‐up period between baseline and 3 years, the largest portion of CAL gain occurred between 1 and 3 years. Indeed, 65% of the cases showed no loss of attachment and 30% of the cases presented with CAL gain in the period between 1 and 3 years of follow‐up. These observations indicate the presence of a stable soft tissue seal around implants that were designed to match a buccal‐lingual sloped configuration of the alveolar ridge. Although no data on CAL changes were reported in studies on similar types of implants (Lee & Siu, 2016; Noelken et al., 2021; Schiegnitz et al., 2017), an increase in the width of the keratinized peri‐implant mucosa was observed during follow‐up. The observations on stable soft tissue conditions over time are in agreement with results reported in long‐term studies on implants with a regular geometry (Cooper et al., 2010; De Bruyn et al., 2013; Donati et al., 2015). The present study also demonstrated that healthy peri‐implant tissues were preserved around >90% of the implants over the 3 years period. The prerequisites for the successful outcome in disease prevention are attributed to appropriately designed single crowns on the implants that allowed access to oral hygiene procedures in combination with a sufficient compliance level by the patient.
In the interpretation of results from the present study, some limitations need to be considered. The study was designed as a multicenter prospective observational study without a well‐defined control group. As indicated above, however, a control group may be considered difficult due to ethical reasons. Thus, placing implants with a regular geometry in a ridge with a lingual‐buccal sloped configuration would require decisions on additional procedures, including ridge augmentation, resection of bony walls, and an apically positioned implant, as shown in preclinical studies (Carmagnola et al., 1999; Welander et al., 2009).
5. CONCLUSION
The present multicenter prospective observational study demonstrated that hard and soft tissues formed around dental implants designed to match the morphology of an alveolar ridge with a lingual‐buccal sloped configuration remained stable over 3 years.
AUTHOR CONTRIBUTIONS
Mauro Donati: Writing – original draft (lead). Robert Noelken: Investigation (equal). Joseph Fiorellini: Investigation (equal). Nils Cladius Gellrich: Investigation (equal). William Parker: Investigation (equal). Tord Berglundh: Supervision (lead); writing – review and editing (lead).
CONFLICT OF INTEREST
Dr. Berglundh reports speaker honoraria from Osteology Foundation and Dentsply Sirona Implants and research grants from Dentsply Sirona Implants and Osteology Foundation. Dr. Gellrich reports grants from KLS Martin Group. Drs. Donati, Noelken, Fiorellini, and Parker report no conflict of interest.
ACKNOWLEDGMENT
This study was supported by grants from Dentsply Sirona Implants/Astra Tech AB, Mölndal, Sweden.
Donati, M. , Noelken, R. , Fiorellini, J. , Gellrich, N.‐C. , Parker, W. , & Berglundh, T. (2023). Implants placed in an alveolar ridge with a sloped configuration. A 3‐year prospective multicenter study. Clinical Oral Implants Research, 34, 13–19. 10.1111/clr.14012
DATA AVAILABILITY STATEMENT
Data sharing not applicable to this article as no datasets were generated or analysed during the current study
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
Data sharing not applicable to this article as no datasets were generated or analysed during the current study