University of Groningen Soft tissue grafting and single implant treatment in the aesthetic region Zuiderveld, Elise

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Soft tissue grafting and single implant treatment in the aesthetic region

Zuiderveld, Elise

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Zuiderveld, E. (2018). Soft tissue grafting and single implant treatment in the aesthetic region. Rijksuniversiteit Groningen.

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Soft tissue grafting and

single implant treatment

in the aesthetic region

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This research project was supported by:

Nobel Biocare Services AG (Kloten, Switzerland) with a partial material grant, internal study code 2012- 1135

Geistlich Pharma AG (Wolhusen, Switzerland)

Lay-out & Cover: Evelien Jagtman (www.evelienjagtman.com)

Printing: Gildeprint

ISBN: 978-94-034-0740-1

ISBN e-pub: 978-94-034-0741-8

© Elise Zuiderveld, 2018

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Soft tissue grafting and

single implant treatment

in the aesthetic region

Proefschrift

ter verkrijging van de graad van doctor aan de Rijksuniversiteit Groningen

op gezag van de

rector magnificus prof. dr. E. Sterken en volgens besluit van het College voor Promoties.

De openbare verdediging zal plaatsvinden op woensdag 12 september 2018 om 16.15 uur

door

Elisabeth Gerdine Zuiderveld geboren op 30 september 1987

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Prof. dr. H.J.A. Meijer Prof. dr. A. Vissink Beoordelingscommissie Prof. dr. F. Abbas

Prof. dr. G.A. van der Weijden Prof. dr. F.R. Rozema

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Paranimfen Dr. G.C. Boven ir. N.D.H. Zuiderveld

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CHAPTER 1

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General introduction

Single implant treatment in the maxillofacial aesthetic zone has been shown to be a highly reliable treatment procedure for the rehabilitation of a single failing tooth or a single missing tooth (den Hartog et al. 2008, 2011, Jung et al. 2012, Lang et al. 2012, Slagter et al. 2014, Arora et al. 2017). Meanwhile, in times of an increasing demand for an ideal aesthetic outcome of a failing or missing single tooth in harmony with the neighbouring teeth, the focus in research has shifted from implant survival, which has been proven to be very high, towards how to preserve hard and soft peri-implant tissues (Araújo et al. 2015, Tettamanti et al. 2016, Cosyn et al. 2017). This shift in focus has occurred, because recession of the mid-buccal mucosa and the resulting unpleasing aesthetics of the peri-implant mucosa are still rather frequently observed (Raes et al. 2011, Cosyn et al. 2016, Tonetti et al. 2017, Mangano et al. 2017). To achieve a pleasing aesthetic outcome, it is presumed that the mid-buccal peri-implant mucosa has to be supported by a correctly three-dimensional positioned implant with a suf-ficient buccal bone volume (Merheb et al. 2014, Chappuis et al. 2017a). It is not uncommon that there is not sufficient buccal bone volume, as the bone remodelling process following tooth removal has led to a substantial vertical and horizontal resorption of the alveolar ridge, especially at the buccal aspect (Merheb et al. 2014, Araújo et al. 2015). This resorption, in particular when horizontal resorption is severe, results in a deficient buccal bone wall, thus limiting an optimal soft tissue support. As a result the aesthetics of the peri-implant soft tissue are challenged (Chappuis et al. 2017a).

Immediate implant placement and provisionalisation has been proposed to provide immediate support to peri-implant hard and soft tissues in order to limit recession of the mid-buccal mucosa and thus results in more favourable aesthetics (De Rouck et al. 2009). Several studies have demonstrated, however, that the post-extraction resorption process is not countered by immediate implant placement (Araújo et al. 2006, Vignoletti et al. 2012, Merheb et al. 2014). In fact, immediate implant treatment is often accompanied by inherent presumed potential risk factors influencing ridge resorption and mid-buccal mucosa recession, viz. a thin or pre-existing defect of the buccal bone wall, implant positioning too far to the buccal and a thin gingival biotype (Chen & Buser 2014, Del Fabbro et al. 2015, Morton & Pollini 2017). To reduce the effects of bone resorption after tooth removal on peri-implant soft tissues in immediate single implant cases, it has been recommended to place an implant at least 2 mm palatally from the buccal socket wall of the fresh extraction alveolus in combination with grafting of the implant-socket gap (Merheb et al. 2014, Lin et al. 2014, Cardaropoli et al. 2015). Additionally, according to several case series, thickening of the mid-buccal mucosa by applying a connective tissue graft at implant placement has been suggested to further limit recession of the mid-buccal mucosa, especially in the presence of a thin gingival biotype (Kan et al.

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2005, 2009, Chung et al. 2011, Tsuda et al. 2011, Rungcharassaeng et al. 2012). Two randomized controlled trials (RCTs) assessing the additional effect of connective tissue grafting in immediate implant treatment showed a better preservation of the mid-buccal mucosal level (Yoshino et al. 2014, Migliorati et al. 2015), but both studies showed limitations regarding patient selection and measuring changes of the mid-buccal mucosal level. Additionally, both a retrospective study and a 5-year prospective study reported an increased recession of the mid-buccal mucosa despite connective tissue grafting (Cosyn et al. 2016, Kolerman et al. 2016). Therefore, more insight into the added value of connective tissue grafting needs to be established.

When immediate implant placement and provisionalisation after extraction of a single failing tooth is not possible because of insufficient bone volume to provide implant placement in a correct three-dimensional position with sufficient primary stability, implant placement has to be delayed (Buser et al. 2017). Moreover, to limit the dimensional changes of the extraction socket with a large buccal bone defect as a result of physiological bone remodelling after tooth removal, it has been recommended to graft the extraction socket (alveolar ridge preservation) combined with sealing the socket with a mucosa graft. This combined procedure has been shown to favour aesthetics (Raghoebar et al. 2009, Jung et al. 2013, Barone et al. 2013). Although alveolar ridge preservation with the application of a mucosa graft signifi-cantly reduces the amount of bone remodelling, the obtained degree of reduction is highly variable due to local and systemic factors. Therefore, bone loss as well as soft tissue changes still occur and have to be studied in more detail (Barone et al. 2013, Avila-Ortiz et al. 2014, Natto et al. 2017).

If a tooth has been removed without efforts to perform an alveolar ridge preservation proce-dure, physiological bone resorption may result in a substantial reduction of the alveolar ridge, especially at the buccal aspect of the maxillary anterior region (Merheb et al. 2014, Araújo et al. 2015). This outcome may, at least in part, underlie the insufficient aesthetic outcome that has been reported for implant treatment in the aesthetic region (Chappuis et al. 2017a). Local augmentation of the buccal bone wall at implant placement in naturally healed alveolar ridges with guided bone regeneration (GBR) has been shown to effectively increase the buccal soft tissue contour, resulting in less recession of the mid-buccal mucosa, also on the long term (Benic & Hämmerle 2014, Benic et al. 2017, Chappuis et al. 2017b). On the contrary, pre-implant augmentation of a naturally healed buccal bone wall may be accompanied by a less beneficial aesthetic outcome (den Hartog et al. 2013). The best pre-implant bone aug-mentation procedure, if any, to obtain the best aesthetic result later on needs further study. Replacement of a single failing tooth with an implant placed in a preserved alveolar ridge or replacement of a single missing tooth with an implant and guided bone regeneration still might result in a deficient peri-implant mucosa due to soft tissue changes. Thickening of the

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buccal peri-implant soft tissue by means of a soft tissue grafting procedure might compensate for this deficiency (Thoma et al. 2009, Buser et al. 2017). The application of a connective tissue graft at implant placement has been demonstrated to effectively increase the soft tissue contour, resulting in a better aesthetic outcome (Wiesner et al. 2010, De Bruyckere et al. 2015, Hanser & Khoury 2016, Stefanini et al. 2016). Besides, connective tissue grafting showed to be able to limit recession of the mid-buccal mucosa (Schneider et al. 2011, Stefanini et al. 2016). Soft tissue augmentation with connective tissue is currently considered the golden standard for thickening the mid-buccal peri-implant mucosa (Thoma et al. 2014a, b). To reduce patient morbidity as a consequence of the harvesting procedure of connective tissue, a xenogeneic collagen matrix has been introduced (Sanz et al. 2009, Froum et al. 2015). First results are promising in terms of increasing soft tissue thickness. Thus, a xenogeneic collagen matrix may serve as a proper alternative to connective tissue grafting, but is in need of further evaluation, especially in terms of the ability to limit recession of the mid-buccal mucosa (Lorenzo et al. 2012, Cardaropoli et al. 2012, Jepsen et al. 2013, Thoma et al. 2016, Zeltner et al. 2017, Maiorana et al. 2018). While there are an increasing number of studies assessing the effect of soft tissue grafting, especially of a xenogeneic collagen matrix, in single implant treatment, most studies reported in the literature focus on the effect on soft tissue volume instead of the change in mid-buccal mucosal level (amongst others, Wiesner et al. 2010, Lorenzo et al. 2012, De Bruyckere et al. 2015, Froum et al. 2015, Hanser & Khoury 2016, Thoma et al. 2016, Zeltner et al. 2017, Maiorana et al. 2018). However, in particular the change in mid-buccal mucosal level to a more apical position compared to the contralateral tooth and neighbouring teeth can have a detrimental effect on the aesthetic outcome.

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Aim of the thesis

The general aim of the research described in this thesis was to gain insight into the effect of soft tissue grafting on the condition and aesthetics of the peri-implant tissues in single implant treatment in the aesthetic zone. The specific aims were:

• to assess whether the bucco-palatal implant position, gingival biotype, platform-switching and pre-implant bone augmentation affect the level of the mid-buccal mucosa (Chapter 2); • to assess the effect of connective tissue grafting on the mid-buccal mucosal level of

immediately placed and provisionalised single implants in the maxillary aesthetic zone

(Chapter 3);

• to assess the effect of connective tissue grafting on the preservation of the mid-buccal mucosal level, change in mid-buccal mucosal volume and change in buccal bone thickness in single immediate implants in the aesthetic zone (Chapter 4);

• to describe a surgical approach for removal of primary and impacted secondary canines combined with immediate placement and provisionalisation of an implant (Chapter 5); • to assess whether grafting the buccal peri-implant mucosa at implant placement, either

with connective tissue or a xenogeneic collagen matrix, results in less mid-buccal mucosa recession (Chapter 6);

• to compare the treatment outcome of single implants placed in preserved alveolar ridges versus non-preserved alveolar ridges combined with connective tissue grafting on the mid-buccal mucosal level, bone loss, peri-implant aesthetics and patient satisfaction

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This chapter is an edited version of the manuscript:

Zuiderveld, E.G., den Hartog, L., Vissink, A., Raghoebar, G.M., Meijer, H.J.A. Significance of Buccopalatal Implant Position, Biotype, Platform Switching, and

Pre-im-plant Bone Augmentation on the Level of the Midbuccal Mucosa.

The International Journal of Prosthodontics 2014; 27: 477-479.

CHAPTER 2

Significance of bucco-palatal

implant position, gingival biotype,

platform-switching and pre-implant

bone augmentation on the level of the

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Abstract

Aim:

To assess whether bucco-palatal implant position, gingival biotype, platform-switching and pre-implant bone augmentation affects the level of the mid-buccal mucosa (MBML).

Materials & Methods:

90 patients with a single-tooth implant in the aesthetic zone were included. The MBML was measured on photographs taken one year after crown placement.

Results:

The factors analysed explained 22% of the variance of the MBML. The more an implant was placed to the buccal, the more the MBML was positioned apically. A comparable phenome-non was observed in cases with a thick biotype and cases that underwent pre-implant bone augmentation. Platform-switching did not affect the level of the MBML.

Conclusion:

The factors analysed in this study account for only a small portion of the variance of the MBML.

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Short communication

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Introduction

Hitherto, only few studies have focused on factors influencing the level of the mid-buccal mucosa (MBML). It has been suggested that implants placed too far to the buccal and cases with a thin gingival biotype show more mid-buccal recession (Evans & Chen 2008, Cosyn et al. 2012a). Furthermore, it has been shown that pre-implant bone augmentation is associated with less satisfactory overall soft tissue aesthetics (Cosyn et al. 2012a), but its effect on the posi-tion of the MBML has not been considered yet.The same holds true for the effect of using implants with a non-matching implant abutment diameter (i.e., platform-switching). Although implants with platform-switching show less marginal peri-implant bone loss (Al-Nsour et al. 2012), the effect of platform-switching on the position of the MBML is debatable. Therefore, by means of a multivariate analysis, we assessed the significance of bucco-palatal implant position, gingival biotype, platform-switching, and pre-implant bone augmentation on the mid-buccal mucosal level for single-tooth implants in the aesthetic zone.

Materials & Methods

Ninety patients (53.3% male; mean age: 36.5 years; range: 18-71 years) with a single-tooth implant replacing a central (75.6%) or lateral incisor (24.4%) were included. Patients partici- pated in clinical trials of different implant types and received an implant depending on the study they were enrolled: NobelReplace Groovy and NobelReplace Select (Nobel Biocare AB, Gothenburg) without platform-switching (45 patients) or Straumann Bone Level (Wolhusen, Switzerland) with platform-switching (45 patients). Implants were inserted in healed sites (45.6% with pre-implant bone augmentation) and restored after three months.

Implant position, i.e., its distance from the buccal contour of the alveolar crest, was measured on the definitive crown casts with a digital caliper (Fig. 1). The vertical position of the MBML was measured on photographs taken one year after placement of the implant crown, using the GNU Image Manipulation Program (http://www.gimp.org/; Fig. 2). Negative values, which indicated a more coronally positioned mucosal level compared to the contralateral tooth, were considered as no difference in mucosa position. Measurements were done to the nearest 0.1 mm. Gingival biotype was rated visually on the same photographs based on specific features

according to De Rouck et al. (2009)by two examiners independently. Data were analysed

using IBM SPSS Statistics (version 20.0, SPSS Inc, Chicago, IL, USA). Univariate analyses were performed for each predictor variable. Predictors with a p-value ≤0.2 were entered into a multivariate linear regression model using a stepwise entry procedure. A significance level of 0.05 was chosen.

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Fig. 1 – Measurement of the bucco-palatal implant position

A reference line was drawn between the cervical edges of the neighbouring teeth. The distance of the buccal aspect of the implant to this line was measured with a digital caliper.

Fig. 2 – Measurement of the position of the MBML

After calibration with a periodontal probe, the length of the clinical implant crown along the vertical axis (i.e., distance between incisal edge and mucosal margin) was measured and subtracted from the length of the crown of the contralateral tooth.

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Results

On average, the MBML was located 0.55±0.72 mm more apically compared to the gingival level of the contralateral tooth. Of the total number of implants, 94.4% of the implants were placed at least 1.0 mm palatal to the reference line. 53.3% of the cases were screened as a thin gingival biotype. Multivariate linear regression analysis showed that the factors implant position, gingival biotype, and pre-implant bone augmentation together explained 22% of the variance of the level of the mid-buccal mucosa. Platform-switching provided no contribution to this variance. The more the implant was positioned to the buccal, the more the MBML was situated apically. The same was found for a thick gingival biotype and pre-implant bone augmentation. Results of the analysis are shown in Table 1.

Table 1 – Results of the multiple linear regression analysis.

Variable β p-value R Square

Pre-implant bone augmentation Thick gingival biotype

Implant position .29 .28 -.24 0.005 0.005 0.015 0.086 0.166 0.222

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Discussion

The factors analysed in this study only explained 22% of the variance of the MBML, mean-ing that there are more factors influencmean-ing this position. It might be that the soft and hard tissue levels before implant placement play a dominant role for the final position of the MBML. According to the literature, an intact buccal bone wall is associated with little risk of recession for immediate implant cases (Cosyn et al. 2012b). Although implants in our study were conventionally placed, we hypothesize that a favourable pre-operative situation with little resorption of the buccal bone wall, will lead to a more favourable final position of the MBML, also in conventional cases. This hypothesis might be supported by the finding that in our study a pre-implant bone augmentation contributed most to the variance of the vertical position of the MBML. The fact that a pre-implant bone augmentation is needed implies that the pre-existing architecture is already compromised. Of course, the augmentation procedure itself might also lead to a more apically located MBML.

We found a more apically situated MBML in cases with a thick gingival biotype. This is in contrast with the study by Evans and Chen (2008), showing more mid-buccal recession in cases with a thin gingival biotype. It should be noted, however, that this study only included immediate implant cases. Furthermore, as stated in a recent systematic review (Cosyn et al. 2012b), evidence to support increased risk for mid-buccal recession in patients with a thin gingival biotype is limited. To what extent gingival biotype is of significance, also in conven-tional cases, needs further investigation.

In conclusion, the factors analysed in this study account for only a small portion of the vari-ance of the MBML. The more an implant was placed to the buccal, the more the MBML was positioned apically. A comparable phenomenon was observed in cases with a thick gingival biotype and in cases in which pre-implant bone augmentation was performed, whereas plat-form-switching did not affect the level of the mid-buccal mucosa.

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References

Al-Nsour, M.M., Chan, H.-L. & Wang, H.-L. (2012) Effect of the platform-switching technique on preservation of peri-implant marginal bone: a systematic review. The International journal of oral & maxillofacial implants 27, 138–145.

Cosyn, J., Sabzevar, M.M. & De Bruyn, H. (2012a) Predictors of inter-proximal and midfacial recession following single implant treatment in the anterior maxilla: a multivariate analysis. Journal of clinical periodontology 39, 895–903. Cosyn, J., Hooghe, N. & De Bruyn, H. (2012b) A systematic review on the frequency of advanced recession following

single immediate implant treatment. Journal of clinical periodontology 39, 582–589.

Evans, C.D. & Chen, S.T. (2008) Esthetic outcomes of immediate implant placements. Clinical oral implants research 19, 73–80.

De Rouck, T., Eghbali, R., Collys, K., De Bruyn, H. & Cosyn, J. (2009) The gingival biotype revisited: transparency of the periodontal probe through the gingival margin as a method to discriminate thin from thick gingiva.

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This chapter is an edited version of the manuscript:

Zuiderveld, E.G., Meijer, H.J.A., den Hartog, L., Vissink, A., Raghoebar, G.M. Effect of connective tissue grafting on peri-implant tissue in

single immediate implant sites: A RCT.

Journal of Clinical Periodontology 2018; 45: 253-264.

CHAPTER 3

Effect of connective tissue grafting

on peri-implant tissue in single

immediate implant sites:

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Abstract

Aim:

To assess the effect of connective tissue grafting on the mid-buccal mucosal level (MBML) of immediately placed and provisionalised single implants in the maxillofacial aesthetic zone. Materials & Methods:

Sixty patients with a failing tooth were provided with an immediately placed and provision-alised implant. During implant placement, patients randomly received either a connective tissue graft from the maxillary tuberosity (n=30, test group) or no graft (n=30, control group). Follow-up visits were at one (T1) and twelve months (T12) after final crown placement. The primary outcome measure was any change in MBML compared to the pre-operative situation. In addition, gingival biotype, aesthetics (using the Pink Esthetic Score-White Esthetic Score), marginal bone level, soft tissue peri-implant parameters and patient satisfaction were assessed. Results:

The mean MBML change at T12 was 0.1±0.8 mm in the test group and -0.5±1.1 mm in the control group (p=0.03). No significant differences regarding the other outcome variables were observed, neither was gingival biotype associated with a gain or loss in MBML.

Conclusion:

This one-year study shows that connective tissue grafting in single, immediately placed and provisionalised implants leads to less recession of the peri-implant soft tissue at the mid-buc-cal aspect, irrespective of the gingival biotype.

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Connective tissue grafting in single immediate implants

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Introduction

Immediate single implant placement and provisionalisation (IIPP) in the aesthetic zone is a viable treatment option for replacing failing teeth (Slagter et al. 2014, Del Fabbro et al. 2015). Advantages and benefits for patients are reduced treatment time and employment of only one surgical intervention.

Recession and less favourable pink aesthetics of the mid-buccal mucosa when applying imme-diate implant placement are not uncommon (Chen & Buser 2014, Cosyn et al. 2016, Tonetti et al. 2017). As demonstrated in animal studies, tooth extraction results in loss of bone and soft tissue, especially at the buccal side. This resorption process is not countered by immediate implant placement (Araújo et al. 2006, Vignoletti et al. 2012, Merheb et al. 2014). Presumed potential risk factors influencing ridge resorption and mid-buccal mucosa recession are a thin or pre-existing defect of the buccal bone wall, buccal implant position and a thin gin-gival biotype (Chen & Buser 2014, Zuiderveld et al. 2014, Del Fabbro et al. 2015, Morton & Pollini 2017). To limit the effects of bone remodelling on the mid-buccal mucosa, it was proposed to place implants at least 2 mm from the internal buccal socket wall and to fill the implant-socket gap with a bone graft (Merheb et al. 2014, Lin et al. 2014, Cardaropoli et al. 2015). Additionally, it was suggested to place a connective tissue graft (CTG) during implant placement to thicken the soft tissue (Lin et al. 2014, Lee et al. 2016).

Most studies assessing the use of a CTG in combination with IIPP are case series. They concluded that a connective tissue grafting procedure, with proper 3D-implant positioning and bone grafting of the implant-socket gap, can minimize mid-buccal mucosa recession (Kan et al. 2005, 2009, Chung et al. 2011, Tsuda et al. 2011, Rungcharassaeng et al. 2012). The yet performed RCTs showed that a CTG resulted in fewer MBML changes (Yoshino et al. 2014, Migliorati et al. 2015). Migliorati et al. (2015) also showed a better PES when apply-ing a CTG. However, both RCTs have their limitations. Yoshino et al. (2014) included two small groups of 10 patients and only assessed the change in MBML to the nearest 0.5 mm, without measuring the outcome with aesthetic indices. Migliorati et al. (2015) only included patients with an aesthetically beneficial starting point, thereby reducing the external validity. Yet, a recent systematic review could not find any significant advantages of combining a CTG and a bone graft in relation to implant placement (Khzam et al. 2015). A retrospective study revealed that, despite achieving favourable peri-implant soft tissue results through IIPP combined with soft tissue grafting, the buccal mucosa still recessed by ≥1 mm in 50% of the patients (Kolerman et al. 2016). This is in line with 5-year results showing increased recession despite connective tissue grafting (Cosyn et al. 2016). Thus, well-designed RCTs are needed to establish the added value of a CTG. Therefore, we tested whether applying a CTG results in less mid-buccal mucosa recession in immediate implant cases.

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Materials & Methods

Study design

Consecutive patients (aged ≥18 years) referred for implant treatment between December 2012 and July 2015 due to a single failing tooth in the maxillary aesthetic zone (incisor, canine, first premolar), were considered for inclusion. Patients were eligible if they (i) showed adequate oral hygiene (i.e., modified plaque and sulcus bleeding index ≤1; Mombelli et al. 1987); (ii) had a diastema width of ≥6 mm and sufficient interocclusal space for a non-occluding provisional restoration; (iii) had no medical and general contraindications for the surgical procedure (i.e., ASA score ≥III; Smeets et al. 1998); (iv) had no active and uncontrolled periodontal disease (probing pocket depths ≥4 mm and bleeding on probing (index score >1)); (v) did not smoke; (vi) had not received head and neck radiation, and (vii) were not pregnant (Fig. 1). Informed consent was obtained before enrollment. The study was approved by our Medical Ethical Committee (NL43085.042.13) and registered in a trial register (www.trialregister.nl: NTR3815). Patients were only included if the buccal socket wall had a bony defect of <5 mm in a vertical direction. The height of the bone defect was measured after the failing tooth was extracted, using a periodontal probe at the mid-buccal, mesial and distal aspect of the failing tooth and the adjacent teeth (Slagter et al. 2015). Random allocation was done by sealed envelopes opened by a research-nurse not involved in the study. All patients were treated with tapered implants (NobelActive, Nobel Biocare AB, Gothenburg, Sweden) placed in the extraction socket and immediately restored in combination with

•

a connective tissue graft harvested from the maxillary tuberosity region (test group);

•

no soft tissue graft (control group).

Intervention procedure

Patients started taking antibiotics (amoxicillin 500mg, t.i.d. for 7 days or clindamycin 300mg, q.i.d. for 7 days) a day before the operation. A 0.2% chlorhexidine mouthwash was used twice daily for 7 days.

All surgical procedures were performed under local anaesthesia by one oral and maxillofacial surgeon (G.M.R.). The failing tooth was removed as atraumatically as possible by detaching the periodontal ligament from the failing tooth without raising a flap. The implant site was prepared on the palatal side of the alveolus according to the manufacturer’s manual by using a surgical template representing the ideal position of the prospective implant crown. The last used implant drill was placed as a space maintainer to augment the gap between the drill and peri-implant bone with a 1:1 mixture of autogenous and anorganic bovine bone (Geistlich Bio-Oss®_{, Geistlich Pharma AG, Wolhusen, Switzerland; Slagter et al. 2015). The autogenous}

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bone was harvested from the maxillary tuberosity region. After careful removal of the implant drill, the implant was placed 3 mm apical to the most apical aspect of the prospective clinical crown (Figs. 2a, b).

Fig. 1 – Cohort flow diagram

Assessed for eligibility (n=60)

Enrollment

Excluded (n=0)

‐ Not meeting inclusion criteria - Declined to participate - Other reasons Randomized (n=60)

Lost to follow-up (n=0)

Discontinued intervention (n=1, implant was lost)

Analysed (n=29)

‐ Excluded from analysis (n=0) Allocated to intervention: test group (n=30) ‐ Received allocated intervention (n=30) ‐ Did not receive allocated intervention (n=0)

Lost to follow-up (n=0)

Discontinued intervention (n=1, implant was lost) Allocated to intervention: control group (n=30) ‐ Received allocated intervention (n=30) ‐ Did not receive allocated intervention (n=0)

Analysed (n=29)

‐ Excluded from analysis (n=0)

Allocation

Follow-up

Analysis

An implant-level impression was taken to fabricate a screw-retained lab-made provisional crown using engaging temporary abutment and composite. Then, a corresponding healing abutment was connected to the implant. Next, a split-thickness CTG was harvested from the test group’s maxillary tuberosity region where the bone graft had been taken. The CTG was placed in a supraperiosteal envelope flap prepared at the buccal aspect without using vertical incisions. The CTG was secured with vertical and horizontal mattresses (4-0 vicryl, Johnson & Johnson Gateway, Piscatatway, USA; Fig. 2c). The wounds were closed with Ethilon 5-0 nylon sutures (Johnson & Johnson) in both groups.

The same day as implant placement, the healing abutment was removed and the screw-retained provisional crown was fitted directly onto the implant with 20Ncm and adjusted to free it from centric contacts with antagonist teeth. Patients were instructed to follow a soft diet and to avoid exerting force on the provisional restoration.

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Fig. 2a – Extraction socket with grafted buccal implant-socket gap.

Fig. 2b – Implant is placed in the grafted extraction socket without flap elevation and covered with a temporary abutment.

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Fig. 2c – In addition, in the test group, a connective tissue graft is placed supraperiostealy in an envelope flap buccally from and on top of the grafted extraction socket. The flap and connective tissue graft are secured with sutures.

After a three-month provisional phase, a final open-tray impression was taken at implant level using polyether impression material (Impregum Penta, 3M ESPE, Seefeld, Germany). Next, an individualized zirconia abutment (NobelProcera, Nobel Biocare AB) was made. Abutment screws were torqued with 35Ncm. Depending on the location of the screw access hole, the final crown was screw-retained or cement-retained with glass ionomer cement (Fuji Plus cement, GC Europe, Leuven, Belgium; Slagter et al. 2015).

All prosthetic procedures were accomplished by two prosthodontists (H.J.A.M. and C.S.). Photographic assessment

The primary outcome, MBML change, was assessed one (T1) and 12 months (T12) after

placement of the final implant crown and compared to baseline mucosal levels of the failing

tooth (Tpre) as measured on standardized intra-oral photographs (Canon EOS 650D with

ring flash; Meijndert et al. 2004). Any changes in inter-proximal mucosal levels (IML) were assessed using the same method. For calibration, photographs were taken with a periodontal probe (Williams Color-Coded probe; Hu-Friedy Chicago, IL, USA) held in close contact and parallel to the long axis of the tooth adjacent to the implant and analysed (Adobe Photoshop CS5.1, Adobe Systems Inc., San Jose, USA). At Tpre, a horizontal line was drawn through the

incisal edges of the natural neighbouring teeth (reference line). Next, the distance between the reference line and the mucosal margin of the failing tooth was measured. The measurements

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were repeated at T1. For mid-buccal mucosal level changes between T1 and T12, the incisal

edge of the implant crown was used as a reference (Figs. 3a, b).

The aesthetics of the peri-implant mucosa and implant crown were assessed from photo-graphs taken at T12 using the Pink Esthetic Score-White Esthetic Score (PES/WES; Belser et

al. 2009). When possible, the implant crown was captured in one picture with the neighbouring dentition and contralateral tooth.

Radiographic assessment

A change in marginal bone level was measured from standardized digital intra-oral radiographs taken with an individualized lab-made acrylic splint using the cast model of the dentition (Meijndert et al. 2004), at T1 and T12. Specifically designed software was applied for full-screen

analysis of the radiographs (Slagter et al. 2015). Bone exceeding the implant platform was scored as no bone loss.

Clinical assessments

Clinical data were collected at Tpre, T1 and T12, viz.: (i) gingival biotype, as measured by means of

transparency of a periodontal probe through the gingival margin (only at Tpre; Kan et al. 2010);

(ii) probing pocket depth using a manual periodontal probe at the mesio-buccal, mid-buccal, and disto-buccal and mid-palatal aspect; (iii) amount of plaque (modified plaque index; Mom-belli et al. 1987); (iv) bleeding after probing (modified sulcus bleeding index; MomMom-belli et al. 1987); (v) gingival condition (gingival-index; Loe 1967); (vi) width of the keratinized mucosa: no keratinized mucosa, <1 mm of keratinized mucosa, 1-2 mm of keratinized mucosa, ≥2 mm of keratinized mucosa; (vii) volume of the interproximal papilla, using the papilla index (Jemt 1997); (viii) implant survival; (ix) implant success, defined as ≤1 mm marginal bone loss one-year post-loading and ≤0.2 mm thereafter and the absence of pain, infection, mobility, peri-implant radiolucency and alteration in sensitivity (Albrektsson et al. 1986).

All the measurements were done by a single examiner (E.G.Z.) who was blinded regarding the group allocation.

Patient satisfaction

Patient satisfaction was assessed at Tpre, T1 and T12 using the OHIP-14 questionnaire (van

der Meulen et al. 2012) complemented with questions about overall satisfaction with the current dentition compared to the pre-operative situation (Visual Analogue Scale: VAS). A questionnaire with items regarding aesthetics and satisfaction with the treatment procedure was also completed using VAS-scales. All questionnaires were completed just before clinical data collection and in absence of the examiner.

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Fig. 3a – Measurement of change in MBML between T_pre and T₁.

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Statistical analysis

G*power version 3.1 was used to determine the sample size (Faul et al. 2009).

0.5 mm recession of the mid-buccal mucosa from implant placement to 12 months after placement of the final implant crown was considered as a clinically relevant difference between groups. A minimum of 25 patients per group (one-sided significance level of 5%, power of 80%) was needed to cover the expected standard deviation of 0.7 mm, as derived from the literature (Slagter et al. 2015). Five additional patients were added to each group to compen-sate for withdrawals.

The inter- and intra-observer reliability of the photographic, radiographic and aesthetic assess-ment, according to twelve randomly selected photographs and radiographs (i.e., 15%) judged by two observers (E.G.Z. and L.d.H.) and again repeated by one observer (E.G.Z.) with a two-week interval, was calculated by using the intraclass correlation coefficient (ICC). 95% limits of agreement were depicted.

Normality of the continuous variables was assessed with the Shapiro-Wilk test. Normal Q-Q-plots were depicted. Inter-group differences of normal distributed variables were evaluated with independent t-tests. Non-normal distributed variables were evaluated with Mann-Whitney tests. Categorical data were explored using Chi-square tests or Fisher’s exact tests. Wilcoxon tests were used for within-group statistical analyses.

A regression analysis was done to check the possible confounding influence of gingival biotype and height of the bone defect. First, a crude analysis of the influence of soft tissue grafting on the change in MBML was performed for the time interval Tpre -T12. Next, two

possible confounders were added to the crude analysis to assess their effect on the association. All analyses used p <0.05 to indicate statistical significance (SPSS Statistics 23.0, SPSS Inc.; IBM Corporation, Chicago, IL, USA).

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Results

The characteristics of the 60 included patients and treatment specifications are depicted in Table 1, Figures 4a-c and Figures 5a-c.

No signs of soft tissue complications at the donor site, or extensive bleeding or perforation through the maxillary sinuses were observed. During follow-up, there were no objective signs of infection.

One implant in each group was lost due to failing osseointegration (96.7% implant survival in both groups). At T12, no implants displayed marginal bone loss exceeding 1 mm and all other

success criteria were fulfilled, resulting in a success rate of 96.7% for both groups.

Table 1 – Patient characteristics and treatment specifications per study group.

Variable Test group_(n=30) Control group_(n=30)

Male/female ratio 13/17 15/15

Age (years) mean±SD

(range) (19.5-67.8)45.5±15.5 (20.9-82.2)47.8±16.5

Gingival biotype thin/thick 20/10 15/15

Implant site location I₁/I₂/C/P₁ 16/9/3/2 12/10/7/1

Pre-operative bone defect (mm) mean±SD

3-4/4-5 mm 4.7±0.73/27 4.3±0.96/24

Implant length (mm) 15/18 5/25 7/23

Implant diameter (mm) 3.5/4.3 11/19 14/16

Reliability of photographic and radiographic assessments

ICCs were 0.88 (95% CI 0.72-0.95) and 0.83 (95% CI 0.60-0.93) for the photographic intra- and inter-observer agreement, respectively. Regarding the radiographic assessment, respective ICCs for intra- and inter-observer agreement were 0.71 (95% CI 0.32-0.87) and 0.91 (95% CI 0.75-0.96).

PES/WES ICCs were 0.86 (95% CI 0.68-0.94) and 0.90 (95% CI 0.77-0.96) for intra-observer and inter-observer agreement, respectively.

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Figs. 4a-c (Test group):

a c

b

a Pre-operative clinical situation of the failing right central incisor.

b Clinical situation one year after placement of the right final implant crown.

c Dental radiograph one year after placement of the final implant crown. Change in mid-buccal and interproximal mucosal level

At T12, MBML loss significantly differed between test (0.1±0.8 mm) and the control group

(-0.5±1.1 mm; p=0.03; Table 2). In both groups, the changes in MBML between T1 and T12,

were negligible (p=0.74).

IML at T12 at both sides of the implant was comparable for the test and control group (mesial:

p=0.65, distal: p=0.27; Table 2).

Change in radiographic marginal bone level

Between T1 and T12, the average loss of marginal bone was 0.04±0.46 mm and 0.06±0.42

mm on the mesial side in the test and control group, respectively. Distal sides of the test and control groups gained, on average, 0.02±0.37 mm and 0.03±0.38 mm, respectively. The inter-group results were comparable (test group: p=0.96; control group: p=0.49; Table 2).

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Figs. 5a-c (Control group):

a c

b

aPre-operative clinical situation of the failing left central incisor.

b Clinical situation one year after placement of the left central final implant crown.

c Dental radiograph one year after placement of the final implant crown. Clinical outcome

Data regarding probing pocket depths and papilla volume around the failing tooth and implant crown are depicted in Table 2. No statistical significant differences were found between the groups. At T12, more than 96% of the patients in both groups had no plaque around the

implant crown (score 0). With respect to bleeding after probing, 55% of the test and 45% of the control group patients had none (score 0). Score 1 bleeding after probing (isolated bleeding spots) was encountered in 31% and 45% of the patients and score 2 (confluent red line) in 14% and 10% of the patients in the test and control groups, respectively.

At T12, one patient in the test group had no keratinized mucosa at the buccal side of the

implant (score 0) and one patient had a keratinized mucosa with a width of 1-2 mm (score 2). All other patients had a keratinized mucosa of >2 mm (score 3).

At T12, there were no signs of gingival inflammation (score 0) in 93% of the patients in the

test group and in 100% of the control group. Two patients in the test group had a score 1 (mild inflammation).

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Table 2 – Changes in marginal soft tissue level from baseline to twelve months after outcome measures.

final crown placement and evaluation of marginal bone level, aesthetics and clinical

Test group (n=29) Control group (n=29) Test group (n=29) Control group (n=29) Test group (n=29) Control group (n=29)

Variable T_pre – T₁ (mean±SD) p-value T₁ – T₁₂(mean±SD) p-value T_pre – T₁₂(mean±SD) p-value

MBML (mm) 0.1±0.9 -0.5±1.0 0.02 0.0±0.3 0.0±0.3 0.74 0.1±0.8 -0.5±1.1 0.03

IML

Mesial of implant (mm)

Distal of implant (mm) -0.4±0.7-0.4±0.6 -0.3±0.8-0.6±0.7 0.800.22 -0.1±0.50.2±0.4 -0.1±0.5-0.0±0.4 0.210.86 -0.3±0.7-0.4±0.7 -0.4±1.0-0.6±0.6 0.650.27

T_pre(median (IQR)) p-value T₁ (median (IQR)) p-value T₁₂ (median (IQR)) p-value

Marginal bone level Mesial of implant (mm) Distal of implant (mm) 0.8 (0.0-1.5)0.3 (0.0-1.1) 0.9 (0.2-1.2)0.5 (0.0-1.2) 0.730.93 0.9 (0.4-1.2)0.8 (0.0-1.1) 0.8 (0.5-1.2)0.8 (0.0-1.1) 0.760.99 T_pre(mean±SD) (n=30) p-value T₁(mean±SD) (n=29) p-value T₁₂ (mean±SD) (n=29) p-value PES total Mesial papilla Distal papilla

Curvature of facial mucosa Level of facial mucosa

Root convexity/soft tissue colour and texture

6.4±1.5 1.5±0.5 1.4±0.5 1.3±0.7 1.2±0.5 0.9±0.7 6.8±1.5 1.5±0.5 1.6±0.5 1.5±0.5 1.2±0.5 1.1±0.6 0.21 0.60 0.29 0.37 0.78 0.30 WES total Tooth form Outline/volume Colour (hue/value) Surface texture Translucency/characterization PES/WES total 6.9±1.9 1.2±0.6 1.7±0.5 1.3±0.5 1.3±0.5 1.3±0.6 13.2±2.9 7.4±1.3 1.2±0.4 1.5±0.5 1.6±0.5 1.6±0.5 1.5±0.5 14.2±2.4 0.30 0.69 0.11 0.13 0.04 0.13 0.18 Probing pocket depth (mm)

Mesial of tooth/implant Mid-buccal of tooth/implant Distal of tooth/implant Palatal of tooth/implant 2.8±0.9 2.2±0.9 2.9±1.0 2.6±1.6 2.6±0.9 2.6±1.4 2.5±1.1 2.2±1.0 0.52 0.37 0.07 0.34 3.1±1.4 2.6±1.1 3.0±1.0 2.4±0.7 3.0±1.2 2.2±1.0 2.9±1.4 2.3±0.7 0.90 0.22 0.50 0.64 2.8±1.1 2.3±0.9 2.9±0.9 2.2±0.7 3.0±0.9 2.5±1.2 2.9±1.4 2.3±0.8 0.23 0.81 0.39 0.68 Papilla volume (0/1/2/3/4) Mesial/distal of implant No papilla (score 0)

Less than half papilla (score 1) At least half papilla (score 2) Entire papilla (score 3) Hyperplastic papilla (score 4)

0%/3.4% 13.8%/6.9% 37.9%/34.5% 48.3%/55.2% 0%/0% 3.6%/3.6% 17.9%/14.3% 39.3%/46.4% 39.3%/35.7% 0%/0% 0.74/0.5 0%/0% 10.3%/10.3% 37.9%/31.0% 51.7%/58.6% 0%/0% 0%/0% 13.8%/3.4% 34.5%/37.9% 51.7%/58.6% 0%/0% 1.00/0.66 0%/0% 6.9%/6.9% 27.6%/24.1% 65.5%/69.0% 0%/0% 0%/0% 10.3%/6.9% 41.4%/27.6% 48.3%/65.5% 0%/0% 0.52/1.00

Resulting negative values on subtracting the baseline value (T_pre) from the T₁ and the T₁

(44)

43

CHAPT

ER 3

Table 2 – Changes in marginal soft tissue level from baseline to twelve months after outcome measures.

final crown placement and evaluation of marginal bone level, aesthetics and clinical

Variable T_pre – T₁ (mean±SD) p-value T₁ – T₁₂(mean±SD) p-value T_pre – T₁₂(mean±SD) p-value

MBML (mm) 0.1±0.9 -0.5±1.0 0.02 0.0±0.3 0.0±0.3 0.74 0.1±0.8 -0.5±1.1 0.03

IML

Mesial of implant (mm)

Distal of implant (mm) -0.4±0.7-0.4±0.6 -0.3±0.8-0.6±0.7 0.800.22 -0.1±0.50.2±0.4 -0.1±0.5-0.0±0.4 0.210.86 -0.3±0.7-0.4±0.7 -0.4±1.0-0.6±0.6 0.650.27

T_pre(median (IQR)) p-value T₁ (median (IQR)) p-value T₁₂ (median (IQR)) p-value

Marginal bone level Mesial of implant (mm) Distal of implant (mm) 0.8 (0.0-1.5)0.3 (0.0-1.1) 0.9 (0.2-1.2)0.5 (0.0-1.2) 0.730.93 0.9 (0.4-1.2)0.8 (0.0-1.1) 0.8 (0.5-1.2)0.8 (0.0-1.1) 0.760.99 T_pre(mean±SD) (n=30) p-value T₁(mean±SD) (n=29) p-value T₁₂ (mean±SD) (n=29) p-value PES total Mesial papilla Distal papilla

Curvature of facial mucosa Level of facial mucosa

Root convexity/soft tissue colour and texture

6.4±1.5 1.5±0.5 1.4±0.5 1.3±0.7 1.2±0.5 0.9±0.7 6.8±1.5 1.5±0.5 1.6±0.5 1.5±0.5 1.2±0.5 1.1±0.6 0.21 0.60 0.29 0.37 0.78 0.30 WES total Tooth form Outline/volume Colour (hue/value) Surface texture Translucency/characterization PES/WES total 6.9±1.9 1.2±0.6 1.7±0.5 1.3±0.5 1.3±0.5 1.3±0.6 13.2±2.9 7.4±1.3 1.2±0.4 1.5±0.5 1.6±0.5 1.6±0.5 1.5±0.5 14.2±2.4 0.30 0.69 0.11 0.13 0.04 0.13 0.18 Probing pocket depth (mm)

Mesial of tooth/implant Mid-buccal of tooth/implant Distal of tooth/implant Palatal of tooth/implant 2.8±0.9 2.2±0.9 2.9±1.0 2.6±1.6 2.6±0.9 2.6±1.4 2.5±1.1 2.2±1.0 0.52 0.37 0.07 0.34 3.1±1.4 2.6±1.1 3.0±1.0 2.4±0.7 3.0±1.2 2.2±1.0 2.9±1.4 2.3±0.7 0.90 0.22 0.50 0.64 2.8±1.1 2.3±0.9 2.9±0.9 2.2±0.7 3.0±0.9 2.5±1.2 2.9±1.4 2.3±0.8 0.23 0.81 0.39 0.68 Papilla volume (0/1/2/3/4) Mesial/distal of implant No papilla (score 0)

Less than half papilla (score 1) At least half papilla (score 2) Entire papilla (score 3) Hyperplastic papilla (score 4)

0%/3.4% 13.8%/6.9% 37.9%/34.5% 48.3%/55.2% 0%/0% 3.6%/3.6% 17.9%/14.3% 39.3%/46.4% 39.3%/35.7% 0%/0% 0.74/0.5 0%/0% 10.3%/10.3% 37.9%/31.0% 51.7%/58.6% 0%/0% 0%/0% 13.8%/3.4% 34.5%/37.9% 51.7%/58.6% 0%/0% 1.00/0.66 0%/0% 6.9%/6.9% 27.6%/24.1% 65.5%/69.0% 0%/0% 0%/0% 10.3%/6.9% 41.4%/27.6% 48.3%/65.5% 0%/0% 0.52/1.00

Resulting negative values on subtracting the baseline value (T_pre) from the T₁ and the T₁

(45)

Aesthetic assessment

No significant differences between both groups were noticed with respect to PES and WES total scores and separate items, with the exception of the surface texture of the implant crown in favour of the control group (Table 2). An acceptable level of aesthetics (PES/WES ≥6) was attained in 78.7% of the cases for the peri-implant mucosa and in 85.1% of the cases for the implant crown.

Patient satisfaction

The VAS-scores acquired during follow-up showed no differences in patient satisfaction between the groups (Table 3). Overall, patients reported high levels of satisfaction with the aesthetic outcome (VAS-score of at least 9.0). 77% of the patients would recommend the treatment to others. Within-group comparison of satisfaction with the current dental situation showed a favourable improvement between Tpre and T1 (p=0.00). There was no difference in

Table 3 – Patient satisfaction regarding general satisfaction, aesthetics and treatment procedure.

T_pre (median (IQR)) p-value T₁ (median (IQR)) p-value T₁₂ (median (IQR)) p-value

VAS-questions

How satisfied are you with your current dental

situation? 5.3 (3.9-6.8)* 5.5 (3.8-7.0)* 0.75 8.5 (7.4-8.9)* 8.3 (7.6-9.2)* 0.98 8.3 (6.3-9.2) 8.1 (6.9-8.8) 0.77

How satisfied are you with your current dental situation compared to the situation before treatment?

8.3 (7.6-9.8) 8.5 (7.6-9.1) 0.80 8.7 (6.7-9.6) 8.7 (8.1-9.6) 0.54

How satisfied are you with the implant and the

implant crown? 9.1 (7.9-9.6) 9.2 (8.1-9.8) 0.70 9.3 (7.9-9.9) 9.2 (8.2-9.8) 0.87

Aesthetics

Colour of the crown Form of the crown

Colour of the peri-implant mucosa Form of the peri-implant mucosa

9.3 (7.9-10.0) 9.2 (7.9-9.9) 9.0 (7.3-9.6) 9.2 (7.2-9.5) 9.5 (8.3-9.9) 9.3 (8.1-9.0) 9.3 (8.1-9.9) 8.9 (7.8-9.8) 0.88 0.86 0.53 0.94 9.4 (7.4-9.9) 9.4 (8.8-9.9) 9.2 (7.5-9.9) 8.9 (7.8-9.5) 9.6 (8.6-10.0) 9.3 (8.4-9.9) 9.5 (8.7-9.8) 9.4 (7.7-9.9) 0.56 0.72 0.50 0.44 Treatment procedure

I regret that I chose this treatment

I would recommend the treatment to other patients

0.1 (0.0-0.3)

9.8 (9.2-10.0) 9.7 (8.9-10.0)0.1 (0.0-0.7) 0.820.57 9.8 (9.4-10.0)0.0 (0.0-0.5) 9.6 (8.5-10.0)0.2 (0.0-0.7) 0.410.21

Total OHIP-score 10.0 (6.0-16.0) 10.0 (5.3-19.8) 0.98 3.0 (1.0-9.0)* 6.0 (0.8-1.0)* 0.55 2.0 (1.0-5.0)* 2.0 (0.0-6.0)* 0.60

*p < 0.00 within-group comparison. Abbreviations: T_pre, pre-operative; T₁, one month after final crown placement; T₁₂, twelve

University of Groningen Soft tissue grafting and single implant treatment in the aesthetic region Zuiderveld, Elise

Soft tissue grafting and single implant treatment in the aesthetic region

Zuiderveld, Elise

Soft tissue grafting and

single implant treatment

in the aesthetic region

Soft tissue grafting and

single implant treatment

in the aesthetic region

Contents

CHAPTER 1

General introduction

Aim of the thesis

References

CHAPTER 2

Significance of bucco-palatal

implant position, gingival biotype,

platform-switching and pre-implant

bone augmentation on the level of the

Abstract

Introduction

Materials & Methods

Results

Discussion

References

CHAPTER 3

Effect of connective tissue grafting

on peri-implant tissue in single

immediate implant sites:

Abstract

Introduction

Materials & Methods

•

•

Results