Root-Analogue Implants compared to Forced Orthodontic Extrusion: A retrospective analysis of clinical, radiological and esthetic outcomes after restoration.

doi:10.21203/rs.3.rs-2572215/v1

Objectives

To assess clinical, radiological and esthetic outcomes of prosthodontic rehabilitations supported by root-analogue implants (RAIs) or roots of severely damaged teeth after forced orthodontic extrusion (FOE).

Materials and Methods

Clinical data regarding RAIs and FOE were recorded and retrospectively evaluated for 40 patients by two independent investigators. Functional and esthetic outcomes were assessed for n = 20 pre-molars and n = 20 anterior teeth via comparison of radiographic and digital images applying the novel Functional Implant Prosthodontic Score (FIPS). Krippendorff’s alpha coefficient was calculated to assess inter-rater reliability. Mann-Whitney-U-Test was used to compare the assessed parameters. Level of significance was set to p < 0.05.

Results

Mean observation period for restorations supported by RAIs was 18.4 ± 5.7 months and 43.9 ± 16.4 months for restorations after FOE. Krippendorff’s alpha coefficients did not reveal unacceptable inter-rater reliabilities regarding the investigators and applicability of FIPS. Significant differences were documented when comparing restorations after FOE or supported by RAIs regarding “bone” (p < 0.01), “interproximal” (p < 0.05) and “mucosa” (p < 0.02) in favor of FOE.

Conclusions

Within the limitations of the present retrospective investigation both concepts seem to provide clinically acceptable results. However, bone- and tissue-preserving characteristics of FOE appear to be more promising.

Clinical Relevance:

Especially bone- and tissue-preserving characteristics regarding the concept of FOE are promising. It could be applicable for socket preservation and subsequent conventional implant placements in an adapted workflow.

prosthodontics

endodontically treated tooth

forced eruption

orthodontic extrusion

dental implants

root-analogue implants

In case of extensively destroyed teeth, dentists must regularly decide between tooth preservation or extraction [1, 2]. Regarding this decision, future prosthodontic treatment options to restore function and esthetics should be considered. For the restoration of single-tooth gaps, conventional treatment options such as fixed dental prostheses (FDPs) [3–5], resin-bonded fixed dental prostheses (RBFDPs) [6–8] and implant-retained restorations [3, 9–13] have been established in daily dental routine. Usually, at this clinical state, teeth have already been removed or are expected to be extracted.

However, it is well known that tooth extraction is accompanied by remodeling processes of the surrounding hard and soft tissues whereby volume is usually lost [14]. This can lead to restorative limitations in general and become a challenge, especially in the esthetic zone. To counteract these resorption processes after extraction, immediate implant placement continues to be controversially discussed [15–21]. Thereby, root-analogue implants (RAIs) represent a highly individual procedure of immediate dental implant installations. Like the Dental Polymer Implant Concept already introduced in 1969 [22], the latest attempt to establish RAIs with the REPLICATE Immediate Tooth Replacement System by NDI Berlin resulted in bankruptcy in January 2020. However, RAIs are still available by other manufacturers. Recently published data revealed stable peri-implant soft tissue conditions and satisfying esthetic outcomes regarding RAIs with a survival rate of 94.4% after a short-time observation period of 18.9 ± 2.4 months [23]. Nevertheless, clinical studies on RAIs are scarce, especially compared to those for screw-shaped implants. Therefore, more data were also requested in a recent review [24].

Furthermore, to eliminate the concerns regarding resorption processes, the possibility of tooth/root preservation and restoration should be discussed as a viable treatment option. Thereby, especially the size of defects and subgingival restoration margins can be problematic by affecting the patient’s periodontal health [25] as they might violate biologic width [26]. Additionally, scientific literature demands a circumferential ferrule design preparation for long-term success of restorations [27, 28]. To re-establish biologic width and to facilitate a circumferential ferrule design preparation, pre-prosthetic treatment protocols such as surgical crown lengthening [29] or forced orthodontic extrusion (FOE) procedures [30, 31] have been suggested in the literature. Surgical crown lengthening is an operative procedure associated with an osseous reduction of the alveolar bone and an inevitable lengthening of the clinical crown [32]. This might lead to esthetic deformities, which poses an esthetic problem in the anterior zone. In contrast, with orthodontic extrusion procedures like FOE, soft and hard tissues can be maintained. Therefore, the procedure is regarded maximally tissue preserving and minimally invasive [33]. Although the treatment procedure of FOE was described as early as in 1973 [30] scientific evidence is currently limited to few studies [31, 34, 35].

The aim of this investigation was to evaluate and compare clinical, radiological and esthetic outcomes of prosthodontic rehabilitations supported by RAIs or natural roots after FOE. The working hypothesis was, that both treatment concepts show comparable results.

2.1 Study design and ethical approval

For the present investigation, available clinical data regarding restorations supported by RAIs or natural roots after FOE were retrospectively evaluated and compared. Ethical approval was given by the local Ethical Committee of Charité – Universitätsmedizin Berlin, Germany (application numbers: EA4/140/18 and EA2/301/20). All RAI-treatments were performed by the author D.H. and respective follow-up examinations by the author M.W.H.B. All FOE-treatments and follow-up examinations were performed by the author M.B. To reduce subjective bias, analyzed outcomes were evaluated independently by both first and last specified authors of this article. All patients have received and signed a written informed consent form and patient information. It was conducted considering the STROBE statement for observational studies (https://www.strobe-statement.org) where applicable.

For treatments with a RAI, the following criteria regarding the patients had to be fulfilled: 1) Non-smokers; 2) No medication affecting the bone metabolism; 3) Non-inflammatory surrounding soft and hard tissues and 4) Bone compartments surrounding the relevant tooth had to be intact. For FOE following inclusion criteria were defined: 1) Patients in need of a restoration of a deeply destroyed tooth with two adjacent teeth; 2) Probing depths ≤ 2mm and defects violating the biologic width and/or a missing ferrule design preparation; 3) Prospective crown-to-root ratio ≤ 1; 4) Tooth mobility ≤ 1 and prospective single-tooth restorations. Teeth with suspicion of hypercementosis/ankylosis, molars and teeth with vertical root fractures were excluded. Treatments were only performed in patients whose compliance regarding the necessary monitoring was expected.

Due to the retrospective comparative study design, the cases to be evaluated had to be selected based on the available data. Therefore, n = 10 pre-molars restored with single crowns supported by RAIs, n = 10 severely damaged roots of pre-molars restored with single crowns after FOE, n = 10 anterior teeth (canine to canine) restored with single crowns supported by RAIs and n = 10 severely damaged roots of anterior teeth restored with single crowns after FOE were selected. Thus, 40 cases could be included. Available data were anonymized, retrospectively evaluated and statistically analyzed. Post-hoc power-analysis was performed with a free-to use software to calculate statistical power (G* Power 3.1.9.7, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany) with a sample size of n = 20 per group, α = 0.05 and an effect size of 1.17 resulting in a power of 0.97 (97%).

2.2 Root-analogue implants (RAIs)

For rehabilitations with RAIs, these had to be manufactured individually before surgeries. Impressions were taken with customized trays and a polyether material (Impregum, 3M Deutschland GmbH, Neuss, Germany). These were cast with type IV plaster and digitized with a laboratory scanner where after the model data were available as Standard Triangle/Tessellation Language (STL) datasets. Bite records were taken with an injectable elastomeric A-silicone (Futar D, KettenbachGmbH&Co. KG, Eschenburg, Germany) and DICOM data were exported from an x-ray device (PAX i-3D, VATECH, Hwaseong-si, Gyeonggi-do, South Korea). A highly trained specialist of the manufacturer superimposed the DICOM and STL data and designed the Temporary Protective Covers (TPCs), implant and abutment portions of the RAIs and Try-Ins (exact copies of the RAIs made from sterilizable resin). From resulting Computer Aided Design (CAD) data, TPCs and RAI components were milled in a Computer Aided Manufacturing (CAM) process. All ceramic parts (abutment portion, root portion in case of all-ceramic RAIs and TPCs) were made of yttria-stabilized tetragonal polycrystalline zirconia (Y-TZP) and sintered. With hybrid RAIs, root portion was manufactured from pure titanium (medical grade IV) and bonded to the aforementioned abutment portions made from Y-TZP in a special oven process using a biocompatible glass material without any voids. These connections were checked using x-rays within quality control. Afterwards, root portions of both (all-ceramic and hybrid RAIs) were modified with macro- and micro retentions. The Benex Extraction-System (Benex Extraction-System, Helmut Zepf Medizintechnik GmbH, Seitlingen-Oberflacht, Germany) was used to remove teeth minimally invasive in vertical direction. If this was not successful, teeth were carefully removed using conventional extraction techniques. Intact surrounding bone compartments were obligatory. The expected fit of RAIs was tested by using the respective Try-Ins. Before implant insertion, implant surfaces and alveoli were wetted with Plasma Rich Growth Factors (PRGFs; BTI Biotechnology Institute, San Antonio, Spain). RAIs were carefully placed and present voids were filled with PRGFs as well. As load protection TPCs were semi-adhesively attached (RelyX Ultimate, 3M Deutschland GmbH) to one or both adjacent teeth depending on the design. This provided a protective gap of approx. 0.6mm between the abutment portion of RAIs and TPCs it selves. The workflow has already been described and illustrated in detail in a publication in 2020 [23]. Healing was usually checked 3–6 month after surgeries using clinical and radiological parameters. Prosthodontic treatments were performed in the office of the author D.H. and different referring dentists, whereby no constantly defined workflow was followed. In total, 16 hybrid and four all-ceramic RAIs with respective restorations were investigated.

2.3 Forced orthodontic extrusion (FOE)

Prior to orthodontic extrusion, probing depths, tooth mobility, defect size and radiographic images were assessed in order to determine the amount of extrusion and the prospective crown-to-root ratio for each patient individually. Interocclusal available space for orthodontic extrusion was analyzed with the aid of gypsum models. After removal of insufficient restorations a fiber-reinforced composite-based post (Extrusion pin, Komet Dental, Lemgo, Germany) was placed on the root surface of respective teeth with self-adhesive resin (RelyX Unicem 2 Automix, 3M Deutschland GmbH) in central vestibulo-oral direction, at the widest root diameter. A second post serving as anchorage was adhesively bonded to adjacent teeth with flowable composite resin (Tetric EvoFlow, Ivoclar Vivadent AG, Schaan, Liechtenstein). Elastics were placed in the orthodontic appliance to initiate forced orthodontic extrusion with forces > 0.5N. At the same appointment, supra-crestal fibrectomy, scaling and root planning procedures were performed [36]. In some clinical cases two bars had to be bonded to adjacent teeth due to minor occlusal space. In clinical situations requiring crown restorations on neighboring teeth, anchorage was realized with the aid of a provisional FDP and a reduction of the pontic area in order to allow for a sufficient amount of extrusion. Clinical details on the workflow have already been described and published [34]. Elastics were changed by the patients twice on a daily basis due to the loss of tension. Patients were available for control visits once a week. The mean amount of extrusion was 3.50 ± 0.87mm and the mean time of extrusion 17.88 ± 10.98 days. After extrusion, teeth were bonded to adjacent teeth with composite resin (Tetric EvoFlow, Ivoclar Vivadent AG) for a retention period of at least 8 weeks (mean time of retention 130.60 ± 89.12 days) to prevent orthodontic relapse [37]. After revision of endodontic fillings, placements of glass-fiber posts (X-Post, DentsplySirona, Bensheim, Germany) were performed where indicated, teeth were built up with composite resin and restored with single crowns.

2.4 Study parameters

Within the framework of a feasibility analysis regarding this investigation, existing data sets were reviewed for completeness by the authors M.B. and M.W.H.B. to be able to compare restorations supported by RAIs or natural roots after FOE. The novel Functional Implant Prosthodontic Score (FIPS) was chosen [38] for evaluation and slightly modified with regard to rehabilitations of natural roots after FOE not representing implant-retained restorations (Table, Table 1). It was selected as it is a straightforward, self-explaining, reliable, reproducible and quickly applicable score [38, 39].

Table 1

Definition of the Functional Implant Prosthodontic Score (FIPS) with slight adjustments regarding the evaluation of FOE restorations [33].
Variables	0	1	2
Interproximal Contacts and papillae	Major discrepancy (2x incomplete)	Minor discrepancy (1x complete)	No discrepancy (2x complete)
Occlusion Static and dynamic	Major discrepancy (supra-contact)	Minor discrepancy (infra-occlusion)	No discrepancy
Design Contour and color	Major discrepancy (contour/color deficiencies)	Minor discrepancy (color deficiencies)	No discrepancy
Mucosa Quality and quantity	Non-keratinized Non-attached	Non-keratinized attached	Keratinized attached
Bone X-ray	Radiographic bone loss > 1.5 mm (RAIs) or > 10% (FOE)	Radiographic bone loss < 1.5 mm (RAIs) or < 10% (FOE)	No radiographic bone loss
Maximum score			10

Five variables evaluating interproximal, occlusion, design, mucosa and bone including corresponding sub-categories. Abbreviations: (1) RAIs: Root-analogue implants; (2) FOE: Forced orthodontic extrusion.

FIPS is defined by five variables, allowing to evaluate the interproximal area, the occlusion, the design, the mucosa and the bone. After rating every mentioned parameter with 0, 1 or 2, a maximum score of 10 can be achieved by a single restoration (Table 1). In case of subcategories (i.e. “interproximal” with “contacts” and “papillae”) with different ratings, the lowest has to be selected. Therefore, for evaluation, following data had to be present: 1) Photographs for the visual assessment of papillae, the design/esthetics of the restorations, and the mucosa; 2) Documented information regarding the interproximal contacts (checked with dental floss); 3) Documented information regarding the static and dynamic occlusion (checked with shimstock foil, thickness: 8µm); 4) Available x-rays for the evaluation of marginal bone loss.

For evaluation of interproximal bone changes regarding restorations of severely damaged roots after FOE, radiographic images of teeth before intervention and at recall appointments were superimposed. Therefore, reference lines were drawn on apices and incisal edges of neighboring teeth. The root length of the extruded tooth was divided into ten equal segments. An interproximal bone change of one tenth in a section was defined as interproximal bone loss [40]. A stable interproximal bone level was rated with 2, a change in one tenth of a section was rated with 1 and an interproximal bone loss of more than one tenth of a section was rated with 0 (Figure, Fig. 1).

Due to the availability of the implant lengths of RAIs, the evaluation of bone loss could be carried out in accordance with FIPS score after superimposition of pre- and post-loading x-rays using mathematical rule of three (Fig. 2). Total marginal bone loss without a view to the rough-smooth border between implant and abutment portions were rated. Due to the retrospective study design, no individual bite holders could be used for both investigated concepts.

2.5 Statistical analysis

All statistical tests were performed by an independent examiner using “SciPy” (https://scipy.org/, last accessed 13th of March, 2022), a Python-based open source software environment mainly used for scientific analysis, visualizations and related activities. Krippendorff’s alpha coefficient was calculated to assess inter-rater reliability between the authors M.W.H.B. and M.B. Due to ordinal FIPS data, Mann-Whitney-U-Test was used to compare the assessed parameters regarding restorations of natural roots after FOE or supported by RAIs. Level of significance was set to p < 0.05.

Figure 1 Study participant treated with a single-crown after FOE treatment in regio 24 (FDI).

Illustration based on original publication of FIPS: (a) lateral and (b) occlusal views as well as (c) 2D radiographic image. Abbreviations: (1) FOE: Forced orthodontic extrusion; (2) FDI: Fédération Dentaire Internationale; (3) FIPS: Functional Implant Prosthodontic Score [33].

Figure 2 Study participant treated with a RAI-supported single-crown in regio 24 (FDI).

Illustration based on original publication of FIPS: (a) lateral and (b) occlusal views as well as (c) 2D radiographic image. Abbreviations: (1) RAI: Root-analogue implant; (2) FDI: Fédération Dentaire Internationale; (3) FIPS: Functional Implant Prosthodontic Score [33].

After analysis of available datasets, 40 patient cases could be retrospectively evaluated. Mean age of patients treated with RAIs was 55.9 ± 14.0 years and 47.3 ± 18.5 years for FOE. The gender ratio for RAIs was 70% females and 30% males, for FOE 45% females and 55% males. Evaluation of RAI-supported restorations was based on data raised 18.4 ± 5.7 months after intervention. For restorations of natural roots after FOE, the observation period was calculated to be 43.9 ± 16.4 months. Survival rates for all investigated restorations was 100%. Ceramic chipping was documented for one restoration each (FOE and RAI) within the follow-up period. Additionally orthodontic relapse occurred in three teeth (15%). Detailed information regarding FIPS including means and standard deviations (SD) for both investigators are shown in Table 2. Krippendorff’s alpha coefficients did not reveal unacceptable inter-rater reliabilities regarding the investigators and applicability of FIPS for both concepts, FOE and RAIs (Tables 3 and 4). Due to “occlusion” ratings of FIPS = 2 for all investigated restorations, no statistical evaluation could be carried out in this regard. However, statistical analysis revealed significant differences comparing restorations of natural roots after FOE or supported by RAIs. For both authors (M.W.H.B. and M.B.) significant differences were documented when comparing the concepts of FOE and RAIs regarding “bone” in favor of FOE (p < 0.01, Table 2). For M.B. significant differences were also documented regarding “interproximal” (p < 0.05) and “mucosa” in favor of FOE (p < 0.02, Table 2).

Table 2

Summarized mean FIPS scores including standard deviations (SD) for each variable [33].
	FOE		RAIs
M.B. / M.W.H.B.
n = 20 patients each (FOE and RAIs)	Mean	SD	Mean	SD
Interproximal Contacts and papillae	1.7* / 1.6	0.57 / 0.60	1.45* / 1.45	0.51 / 0.51
Occlusion Static and dynamic	2.0 / 2.0	0.0 / 0.0	2.0 / 2.0	0.0 / 0.0
Design Contour and color	1.55 / 1.40	0.61 / 0.68	1.55 / 1.70	0.61 / 0.47
Mucosa Quality and quantity	1.95* / 1.85	0.22 / 0.37	1.65* / 1.60	0.59 / 0.68
Bone X-ray	1.95* / 1.95*	0.22 / 0.22	0.7* / 0.95*	0.73 / 0.83
Total scores	9.2 / 8.8	1.10 / 1.20	7.35 / 7.7	1.27 / 1.49

Abbreviations: (1) M.B. and M.W.H.B.: first and last named authors; (2) RAIs: Root-analogue implants; (3) FOE: Forced orthodontic extrusion. *indicates significant difference between FOE and RAIs (interproximal: p < 0.05; mucosa: p < 0.02; bone: p < 0.01).

Table 3

Krippendorff’s alpha coefficients showing inter-rater reliabilities between authors M.B. and M.W.H.B. [41].
	Interproximal	Occlusion	Design	Mucosa	Bone
RAIs	1.0	N/A	0.59	0.60	0.73
FOE	0.79	N/A	0.82	0.46	1.0
Abbreviations: (1) M.B. and M.W.H.B.: first and last named authors; (2) RAIs: Root-analogue implants; (3) FOE: Forced orthodontic extrusion.

Table 4

Interpretation guideline following McHugh’s strict classification showing inter-rater reliabilities [41].
Value	Level of agreement	% of data that are reliable
Above .90	Almost perfect	0–4%
.80 − .90	Strong	4–15%
.60 − .79	Moderate	15–35%
.40 − .59	Weak	35–63%
.21 − .39	Minimal	64–81%
0 − .20	None	82–100%

To the best knowledge of the authors, the present study is the first that compares restorations supported by RAIs or natural roots preserved by means of FOE. A retrospective data evaluation was performed because both concepts required for comparable basic prerequisites: deeply destroyed teeth that would have been extracted due to their extension of decay in many cases [23,34]. In addition, little scientific data is available for both treatment options, mainly consisting of case reports and case series [42-53]. Therefore, more clinical data is desirable and has already been demanded [23,34,54]. Working hypothesis must be rejected in particular with regard to marginal bone levels in favor of the concept of FOE.

FIPS was chosen for evaluations as it combines functional, esthetic and radiographic parameters, while being a simple, self-explaining, reliable, reproducible and quickly applicable score [38,39]. Although initially developed for comparison of implant-retained restorations it allows the assessment of clinical and functional parameters for both treatment concepts. Moreover, it might document risk factors and might allow for long-term prognosis. In comparison, this is not the case with other assessment measures such as the pink and white esthetic score [55,56] or the United States Public Health Service (USPHS) criteria [57]. FIPS is therefore a simple and reproducible score for (implant-supported) restorations [38,39]. Thereby, it should be mentioned, that FIPS was originally developed for implant-retained restorations. However, four out of five parameters can be applied analogously (Tab. 1). Documented mean scores of 9.2/8.8 ±1.1/1.2 (FOE) and 7.4/7.7 ±1.3/1.5 (RAIs, Tab. 2) represent highly satisfying results regarding investigated cases, especially for restorations of natural roots after FOE. An adapted assessment of bone loss after FOE as described in materials and methods was applicable (Tab. 1).

Taking a separate look at the sub-parameters of FIPS, for both investigators, evaluated bone loss was significantly higher after immediate placement of RAIs compared to the concept of FOE (p < 0.01, Tab. 2). This result is also supported by the documented “moderate” (RAIs) to “almost perfect” (FOE) inter-rater reliabilities (Tab. 3 and 4). For the author M.B. significantly better scores were also achieved regarding “interproximal” (p < 0.05) and “mucosa” (p < 0.02, Tab. 2) after utilizing the concept of FOE. These results are supported by “moderate” (FOE) to “almost perfect” (RAIs) inter-rater reliabilities (Tab. 3 and 4) regarding "interproximal", though no statistically significant differences were documented for the author M.W.H.B. However, for “mucosa” only weak inter-rater reliabilities were documented (Tab. 3 and 4), which should put the interpretation into perspective and may indicate subjective bias.

According to these results, it can be assumed that the concept of FOE seems to prevent marginal bone loss compared to immediate implant installation of RAIs. This tendency in favor of the concept of FOE can also be observed regarding soft tissues, which, however, seems to have a more subjective component than in the assessment of bone. In comparison a mean pink esthetic score of 7.45 ±1.50, representing highly satisfying results as well, was documented in an extensive follow-up study of RAIs in 2020 [23].

Both treatment options are strongly limited by their inclusion criteria as described in the material and methods section. Functional aspects and available occlusal space are particularly important. Regarding RAIs, preservation of surrounding bones during surgery is mandatory. Additionally, its fit can only be checked intraoperatively, after the root has already been removed. Thus, complications can lead to short-term discontinuation of treatment. For the concept of FOE main limitations are patient’s compliance as they are expected to change the orthodontic elastics and losses of the applied fiber-reinforced posts on root surfaces or neighboring teeth. However, no severe complications can be induced, but quite the opposite: FOE can be an alternative in case of absolute contraindications regarding implant therapy [58,59], limitation of treatment costs [60] and for growing, young patients [61,62].

Despite possible limitations and complications, it should be noted that conventional restorations with FDPs, RBFDPs or conventional screw-shaped implants are still possible even if RAI-supported restorations or restorations of natural roots after FOE fail. However, with regard to the results of marginal bone loss, possible compromised bone volume after RAI loss should be critically kept in mind. No data in this context is available in the literature.

Though bone loss based on two-dimensional x-rays was applied in numerous publications [63,64], findings should be interpreted with care. Additionally, the retrospective design and no use of standardized radiographs with customized x-ray holders are limiting the meaningfulness of the results. Furthermore, it has to be mentioned, that the mean clinical service differed between 18.4 ±5.7 months (RAIs) and 43.9 ±16.4 months (FOE). Marginal bone loss in the RAI group might even be higher as reported after the mean service time of restorations utilizing the concept of FOE. Presumably clinical, radiological and esthetic outcomes of restorations after FOE recorded after approx. 1.5 years wouldn’t effect FIPS values negatively compared to after approx. 3.5 years as specified. In order to minimize subjective bias, all patient cases were assessed by two practitioners independently. Additionally, inter-rater reliabilities were calculated with Krippendorff’s alpha and McHugh’s strict interpretation model was applied [41]. Compared to other interpretations, inter-rater reliability of 0.40 – 0.59 is thereby already described as “weak”, whereas it is described as “fair”, “good” or “moderate” in other interpretation scales. However, it demonstrated, that the “own" procedure tends to be rated as better than the "other" one, respectively. Thus, these results confirm, but also put into perspective, the objectivity of FIPS. This may also highlight the influence of subjective bias especially with regard to studies with a single examiner/practitioner. In this regard, it should be noted in conclusion that all RAI-treatments were performed by the author D.H. and respective follow-up examinations by the author M.W.H.B. Furthermore, all FOE-treatments and follow-up examinations were performed by the author M.B. It would have been more desirable if the assessment by means of FIPS had been carried out by at least a single or multiple completely independent practitioners. However, regarding the additional effort and the specialty of treatment procedures, this was not implemented. In conclusion, this should be kept in mind as source of bias despite calculations and discussion of inter-rater reliabilities.

It can be concluded that both concepts are equal opportunities in restoring deeply destroyed, i.e. “unrestorable”, teeth showing clinically acceptable results. Nevertheless, they primarily play a role alongside conventional prosthetic treatment options as FDP, rbFDP or an implant-retained single crown. However, especially bone- and tissue-preserving characteristics regarding the concept of FOE are promising. It might also be applicable regarding scheduled socket preservation and subsequent conventional dental implant placement in an adapted workflow [65]. Further long-term data on success, survival, functional and esthetic outcomes are still desirable for both concepts.

Author Contribution

M.W.H.B.: Conception and design, acquisition, analysis and interpretation of data, drafting the manuscript, giving final approval; F.B.: Conception and design, interpretation of data, revising the manuscript, giving final approval; M.N.: Conception and design, interpretation of data, revising the manuscript, giving final approval; B.C.S.: Conception and design, interpretation of data, revising the manuscript, giving final approval; S.N.: analysis and interpretation of data, revising the manuscript, giving final approval; D.H.: acquisition and analysis of data, revising the manuscript, giving final approval; M.B.: Conception and design, acquisition, analysis and interpretation of data, drafting the manuscript, giving final approval.

Ethics Approval and Consent to Participate

Ethical approval was given by the local Ethical Committee of Charité – Universitätsmedizin Berlin, Germany (application numbers: EA4/140/18 and EA2/301/20). All patients have received and signed a written informed consent form and patient information.

Funding

Not applicable.

Conflict of Interest

The authors declare no conflicts of interest.

Acknowledgements

This investigation was supported by clinical data from the private dental office of Dr. Detlef Hildebrand in Berlin, Germany and product specific data provided by former company NDI Berlin in Berlin, Germany.

Torabinejad, M.; Anderson, P.; Bader, J.; Brown, L.J.; Chen, L.H.; Goodacre, C.J.; Kattadiyil, M.T.; Kutsenko, D.; Lozada, J.; Patel, R.; et al. Outcomes of root canal treatment and restoration, implant-supported single crowns, fixed partial dentures, and extraction without replacement: a systematic review. J Prosthet Dent 2007, 98, 285-311, doi:10.1016/S0022-3913(07)60102-4.
Pjetursson, B.E.; Heimisdottir, K. Dental implants - are they better than natural teeth? Eur J Oral Sci 2018, 126 Suppl 1, 81-87, doi:10.1111/eos.12543.
Pjetursson, B.E.; Bragger, U.; Lang, N.P.; Zwahlen, M. Comparison of survival and complication rates of tooth-supported fixed dental prostheses (FDPs) and implant-supported FDPs and single crowns (SCs). Clin Oral Implants Res 2007, 18 Suppl 3, 97-113, doi:10.1111/j.1600-0501.2007.01439.x.
Sailer, I.; Pjetursson, B.E.; Zwahlen, M.; Hammerle, C.H. A systematic review of the survival and complication rates of all-ceramic and metal-ceramic reconstructions after an observation period of at least 3 years. Part II: Fixed dental prostheses. Clin Oral Implants Res 2007, 18 Suppl 3, 86-96, doi:10.1111/j.1600-0501.2007.01468.x.
Lulic, M.; Bragger, U.; Lang, N.P.; Zwahlen, M.; Salvi, G.E. Ante's (1926) law revisited: a systematic review on survival rates and complications of fixed dental prostheses (FDPs) on severely reduced periodontal tissue support. Clin Oral Implants Res 2007, 18 Suppl 3, 63-72, doi:10.1111/j.1600-0501.2007.01438.x.
Pjetursson, B.E.; Tan, W.C.; Tan, K.; Bragger, U.; Zwahlen, M.; Lang, N.P. A systematic review of the survival and complication rates of resin-bonded bridges after an observation period of at least 5 years. Clin Oral Implants Res 2008, 19, 131-141, doi:10.1111/j.1600-0501.2007.01527.x.
Kern, M. Clinical long-term survival of two-retainer and single-retainer all-ceramic resin-bonded fixed partial dentures. Quintessence Int 2005, 36, 141-147.
Kern, M. Fifteen-year survival of anterior all-ceramic cantilever resin-bonded fixed dental prostheses. J Dent 2017, 56, 133-135, doi:10.1016/j.jdent.2016.11.003.
Pjetursson, B.E.; Thoma, D.; Jung, R.; Zwahlen, M.; Zembic, A. A systematic review of the survival and complication rates of implant-supported fixed dental prostheses (FDPs) after a mean observation period of at least 5 years. Clin Oral Implants Res 2012, 23 Suppl 6, 22-38, doi:10.1111/j.1600-0501.2012.02546.x.
Jung, R.E.; Pjetursson, B.E.; Glauser, R.; Zembic, A.; Zwahlen, M.; Lang, N.P. A systematic review of the 5-year survival and complication rates of implant-supported single crowns. Clin Oral Implants Res 2008, 19, 119-130, doi:10.1111/j.1600-0501.2007.01453.x.
Roccuzzo, A.; Imber, J.C.; Marruganti, C.; Salvi, G.E.; Ramieri, G.; Roccuzzo, M. Clinical outcomes of dental implants in patients with and without history of periodontitis: A 20-year prospective study. J Clin Periodontol 2022, 49, 1346-1356, doi:10.1111/jcpe.13716.
Schmid, E.; Morandini, M.; Roccuzzo, A.; Ramseier, C.A.; Sculean, A.; Salvi, G.E. Clinical and radiographic outcomes of implant-supported fixed dental prostheses with cantilever extension. A retrospective cohort study with a follow-up of at least 10 years. Clin Oral Implants Res 2020, 31, 1243-1252, doi:10.1111/clr.13672.
Schmid, E.; Roccuzzo, A.; Morandini, M.; Ramseier, C.A.; Sculean, A.; Salvi, G.E. Clinical and radiographic evaluation of implant-supported single-unit crowns with cantilever extension in posterior areas: A retrospective study with a follow-up of at least 10 years. Clin Implant Dent Relat Res 2021, 23, 189-196, doi:10.1111/cid.12973.
Tan, W.L.; Wong, T.L.; Wong, M.C.; Lang, N.P. A systematic review of post-extractional alveolar hard and soft tissue dimensional changes in humans. Clin Oral Implants Res 2012, 23 Suppl 5, 1-21, doi:10.1111/j.1600-0501.2011.02375.x.
Arora, H.; Khzam, N.; Roberts, D.; Bruce, W.L.; Ivanovski, S. Immediate implant placement and restoration in the anterior maxilla: Tissue dimensional changes after 2-5 year follow up. Clin Implant Dent Relat Res 2017, 19, 694-702, doi:10.1111/cid.12487.
Bhola, M.; Neely, A.L.; Kolhatkar, S. Immediate implant placement: clinical decisions, advantages, and disadvantages. J Prosthodont 2008, 17, 576-581, doi:10.1111/j.1532-849X.2008.00359.x.
Clementini, M.; Tiravia, L.; De Risi, V.; Vittorini Orgeas, G.; Mannocci, A.; de Sanctis, M. Dimensional changes after immediate implant placement with or without simultaneous regenerative procedures: a systematic review and meta-analysis. J Clin Periodontol 2015, 42, 666-677, doi:10.1111/jcpe.12423.
Esposito, M.; Grusovin, M.G.; Polyzos, I.P.; Felice, P.; Worthington, H.V. Timing of implant placement after tooth extraction: immediate, immediate-delayed or delayed implants? A Cochrane systematic review. Eur J Oral Implantol 2010, 3, 189-205.
Esposito, M.; Grusovin, M.G.; Polyzos, I.P.; Felice, P.; Worthington, H.V. Interventions for replacing missing teeth: dental implants in fresh extraction sockets (immediate, immediate-delayed and delayed implants). Cochrane Database Syst Rev 2010, CD005968, doi:10.1002/14651858.CD005968.pub3.
Esposito, M.; Zucchelli, G.; Cannizzaro, G.; Checchi, L.; Barausse, C.; Trullenque-Eriksson, A.; Felice, P. Immediate, immediate-delayed (6 weeks) and delayed (4 months) post-extractive single implants: 1-year post-loading data from a randomised controlled trial. Eur J Oral Implantol 2017, 10, 11-26.
Monje, A.; Roccuzzo, A.; Buser, D.; Wang, H.L. Influence of buccal bone wall thickness on the peri-implant hard and soft tissue dimensional changes: A systematic review. Clin Oral Implants Res 2023, doi:10.1111/clr.14029.
Hodosh, M.; Povar, M.; Shklar, G. The dental polymer implant concept. J Prosthet Dent 1969, 22, 371-380, doi:10.1016/0022-3913(69)90200-5.
Böse, M.W.H.; Hildebrand, D.; Beuer, F.; Wesemann, C.; Schwerdtner, P.; Pieralli, S.; Spies, B.C. Clinical Outcomes of Root-Analogue Implants Restored with Single Crowns or Fixed Dental Prostheses: A Retrospective Case Series. J Clin Med 2020, 9, doi:10.3390/jcm9082346.
Dantas, T.; Madeira, S.; Gasik, M.; Vaz, P.; Silva, F. Customized Root-Analogue Implants: A Review on Outcomes from Clinical Trials and Case Reports. Materials (Basel) 2021, 14, doi:10.3390/ma14092296.
Schatzle, M.; Land, N.P.; Anerud, A.; Boysen, H.; Burgin, W.; Loe, H. The influence of margins of restorations of the periodontal tissues over 26 years. J Clin Periodontol 2001, 28, 57-64, doi:10.1034/j.1600-051x.2001.280109.x.
Ingber, J.S.; Rose, L.F.; Coslet, J.G. The "biologic width"--a concept in periodontics and restorative dentistry. Alpha Omegan 1977, 70, 62-65.
Juloski, J.; Radovic, I.; Goracci, C.; Vulicevic, Z.R.; Ferrari, M. Ferrule effect: a literature review. J Endod 2012, 38, 11-19, doi:10.1016/j.joen.2011.09.024.
Naumann, M.; Schmitter, M.; Frankenberger, R.; Krastl, G. "Ferrule Comes First. Post Is Second!" Fake News and Alternative Facts? A Systematic Review. J Endod 2018, 44, 212-219, doi:10.1016/j.joen.2017.09.020.
Baima, R.F. Extension of clinical crown length. J Prosthet Dent 1986, 55, 547-551, doi:10.1016/0022-3913(86)90029-6.
Heithersay, G.S. Combined endodontic-orthodontic treatment of transverse root fractures in the region of the alveolar crest. Oral Surg Oral Med Oral Pathol 1973, 36, 404-415, doi:10.1016/0030-4220(73)90220-x.
Bruhnke, M.; Beuer, F.; Bose, M.W.H.; Naumann, M. Forced orthodontic extrusion to restore extensively damaged anterior and premolar teeth as abutments for single-crown restorations: Up to 5-year results from a pilot clinical study. J Prosthet Dent 2022, doi:10.1016/j.prosdent.2022.08.033.
Krastl, G.; Filippi, A.; Zitzmann, N.U.; Walter, C.; Weiger, R. Current aspects of restoring traumatically fractured teeth. Eur J Esthet Dent 2011, 6, 124-141.
Bach, N.; Baylard, J.F.; Voyer, R. Orthodontic extrusion: periodontal considerations and applications. J Can Dent Assoc 2004, 70, 775-780.
Bruhnke, M.; Bitter, K.; Beuer, F.; Bose, M.W.H.; Neumeyer, S.; Naumann, M. Tooth preservation of deeply destroyed teeth by forced orthodontic extrusion: A case series. Quintessence Int 2022, 0, 2-11, doi:10.3290/j.qi.b2644901.
Malmgren, O.; Malmgren, B.; Frykholm, A. Rapid orthodontic extrusion of crown root and cervical root fractured teeth. Endod Dent Traumatol 1991, 7, 49-54, doi:10.1111/j.1600-9657.1991.tb00183.x.
Carvalho, C.V.; Bauer, F.P.; Romito, G.A.; Pannuti, C.M.; De Micheli, G. Orthodontic extrusion with or without circumferential supracrestal fiberotomy and root planing. Int J Periodontics Restorative Dent 2006, 26, 87-93.
Simon, J.H. Root extrusion. Rationale and techniques. Dent Clin North Am 1984, 28, 909-921.
Joda, T.; Ferrari, M.; Bragger, U. A prospective clinical cohort study analyzing single-unit implant crowns after three years of loading: introduction of a novel Functional Implant Prosthodontic Score (FIPS). Clin Oral Implants Res 2017, 28, 1291-1295, doi:10.1111/clr.12955.
Joda, T.; Zarone, F.; Zitzmann, N.U.; Ferrari, M. The Functional Implant Prosthodontic Score (FIPS): assessment of reproducibility and observer variability. Clin Oral Investig 2018, 22, 2319-2324, doi:10.1007/s00784-017-2332-7.
Krug, R.; Connert, T.; Soliman, S.; Syfrig, B.; Dietrich, T.; Krastl, G. Surgical extrusion with an atraumatic extraction system: A clinical study. J Prosthet Dent 2018, 120, 879-885, doi:10.1016/j.prosdent.2018.02.006.
McHugh, M.L. Interrater reliability: the kappa statistic. Biochem Med (Zagreb) 2012, 22, 276-282.
Chaushu, S.; Zahavi, T.; Becker, A. Forced eruption of maxillary incisor teeth from the lingual side. Quintessence Int 2004, 35, 431-436.
Felippe, L.A.; Monteiro Junior, S.; Vieira, L.C.; Araujo, E. Reestablishing biologic width with forced eruption. Quintessence Int 2003, 34, 733-738.
Kim, S.H.; Tramontina, V.A.; Papalexiou, V.; Luczyszyn, S.M.; Grassi, M.B.; de Fatima Scarpim, M.; Tanaka, O.M. Rapid orthodontic extrusion using an interocclusal appliance for the reestablishment of biologic width: a case report. Quintessence Int 2011, 42, 201-204.
Mangano, F.G.; Cirotti, B.; Sammons, R.L.; Mangano, C. Custom-made, root-analogue direct laser metal forming implant: a case report. Lasers Med Sci 2012, 27, 1241-1245, doi:10.1007/s10103-012-1134-z.
Pirker, W.; Kocher, A. Immediate, non-submerged, root-analogue zirconia implant in single tooth replacement. Int J Oral Maxillofac Surg 2008, 37, 293-295, doi:10.1016/j.ijom.2007.11.008.
Pirker, W.; Kocher, A. Immediate, non-submerged, root-analogue zirconia implants placed into single-rooted extraction sockets: 2-year follow-up of a clinical study. Int J Oral Maxillofac Surg 2009, 38, 1127-1132, doi:10.1016/j.ijom.2009.07.008.
Pirker, W.; Kocher, A. Root analog zirconia implants: true anatomical design for molar replacement--a case report. Int J Periodontics Restorative Dent 2011, 31, 663-668.
Pirker, W.; Wiedemann, D.; Lidauer, A.; Kocher, A.A. Immediate, single stage, truly anatomic zirconia implant in lower molar replacement: a case report with 2.5 years follow-up. Int J Oral Maxillofac Surg 2011, 40, 212-216, doi:10.1016/j.ijom.2010.08.003.
Pontoriero, R.; Celenza, F., Jr.; Ricci, G.; Carnevale, G. Rapid extrusion with fiber resection: a combined orthodontic-periodontic treatment modality. Int J Periodontics Restorative Dent 1987, 7, 30-43.
Saeidi Pour, R.; Randelzhofer, P.; Edelhoff, D.; Prandtner, O.; Rafael, C.F.; Liebermann, A. Innovative Single-Tooth Replacement with an Individual Root-Analog Hybrid Implant in the Esthetic Zone: Case Report. Int J Oral Maxillofac Implants 2017, 32, e153-e160, doi:10.11607/jomi.5562.
Schubert, O.; Beuer, F.; Guth, J.F.; Nold, E.; Edelhoff, D.; Metz, I. Two digital strategies in modern implantology - root-analogue implants and the digital one-abutment/one-time concept. Int J Comput Dent 2018, 21, 115-131.
Zyskind, K.; Zyskind, D.; Soskolne, W.A.; Harary, D. Orthodontic forced eruption: case report of an alternative treatment for subgingivally fractured young permanent incisors. Quintessence Int 1992, 23, 393-399.
Figliuzzi, M.M.; Aiello, D.; Rengo, C.; Parentela, L.; Mangano, C. 10-Year Evaluation of the First Root Analogue Implant on Humans, Made Using a CT Scan, CAD/CAM and DMLS. Biomimetics (Basel) 2022, 7, doi:10.3390/biomimetics7010032.
Belser, U.C.; Grutter, L.; Vailati, F.; Bornstein, M.M.; Weber, H.P.; Buser, D. Outcome evaluation of early placed maxillary anterior single-tooth implants using objective esthetic criteria: a cross-sectional, retrospective study in 45 patients with a 2- to 4-year follow-up using pink and white esthetic scores. J Periodontol 2009, 80, 140-151, doi:10.1902/jop.2009.080435.
Furhauser, R.; Florescu, D.; Benesch, T.; Haas, R.; Mailath, G.; Watzek, G. Evaluation of soft tissue around single-tooth implant crowns: the pink esthetic score. Clin Oral Implants Res 2005, 16, 639-644, doi:10.1111/j.1600-0501.2005.01193.x.
Cvar, J.F.; Ryge, G. Reprint of criteria for the clinical evaluation of dental restorative materials. 1971. Clin Oral Investig 2005, 9, 215-232, doi:10.1007/s00784-005-0018-z.
Chappuis, V.; Avila-Ortiz, G.; Araujo, M.G.; Monje, A. Medication-related dental implant failure: Systematic review and meta-analysis. Clin Oral Implants Res 2018, 29 Suppl 16, 55-68, doi:10.1111/clr.13137.
Chen, H.; Liu, N.; Xu, X.; Qu, X.; Lu, E. Smoking, radiotherapy, diabetes and osteoporosis as risk factors for dental implant failure: a meta-analysis. PLoS One 2013, 8, e71955, doi:10.1371/journal.pone.0071955.
Beikler, T.; Flemmig, T.F. EAO consensus conference: economic evaluation of implant-supported prostheses. Clin Oral Implants Res 2015, 26 Suppl 11, 57-63, doi:10.1111/clr.12630.
Jemt, T.; Ahlberg, G.; Henriksson, K.; Bondevik, O. Changes of anterior clinical crown height in patients provided with single-implant restorations after more than 15 years of follow-up. Int J Prosthodont 2006, 19, 455-461.
Thilander, B.; Odman, J.; Lekholm, U. Orthodontic aspects of the use of oral implants in adolescents: a 10-year follow-up study. Eur J Orthod 2001, 23, 715-731, doi:10.1093/ejo/23.6.715.
Malloy, K.A.; Wadhwani, C.; McAllister, B.; Wang, M.; Katancik, J.A. Accuracy and Reproducibility of Radiographic Images for Assessing Crestal Bone Height of Implants Using the Precision Implant X-ray Locator (PIXRL) Device. Int J Oral Maxillofac Implants 2017, 32, 830-836, doi:10.11607/jomi.5683.
Walton, T.R.; Layton, D.M. Intra- and inter-examiner agreement when assessing radiographic implant bone levels: Differences related to brightness, accuracy, participant demographics and implant characteristics. Clin Oral Implants Res 2018, 29, 756-771, doi:10.1111/clr.13290.
Alsahhaf, A.; Att, W. Orthodontic extrusion for pre-implant site enhancement: Principles and clinical guidelines. J Prosthodont Res 2016, 60, 145-155, doi:10.1016/j.jpor.2016.02.004.

No competing interests reported.

Root-Analogue Implants compared to Forced Orthodontic Extrusion: A retrospective analysis of clinical, radiological and esthetic outcomes after restoration.

Status:

Journal Publication

Version 1

Abstract

Objectives

Materials and Methods

Results

Conclusions

Clinical Relevance:

Figures

1 Introduction

2 Materials And Methods

2.1 Study design and ethical approval

2.2 Root-analogue implants (RAIs)

2.3 Forced orthodontic extrusion (FOE)

2.4 Study parameters

2.5 Statistical analysis

3 Results

Discussion

Conclusion

Declarations

References

Additional Declarations

Status:

Journal Publication

Version 1