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Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants
YBJOM-5299;
No. of Pages 5
ARTICLE IN PRESS Available online at www.sciencedirect.com
ScienceDirect British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx
Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants K. Kniha a,∗ , A. Modabber a , H. Kniha b , S.C. Möhlhenrich c , F. Hölzle a , S. Milz d a
Department of Oral and Cranio-Maxillofacial Surgery, University Hospital Aachen, Pauwelsstraße 30, Aachen 52074, Germany Private Dental Clinic Drs Kniha and Gahlert, Theatinerstraße 1, Munich 80333, Germany c Department of Orthodontics, University Hospital Aachen, Pauwelsstraße 30, 52074, Germany d Department of Anatomy Munich, Ludwig-Maximilians University Munich, Pettenkoferstr. 11, 80336, Germany b
Accepted 10 November 2017
Abstract Preservation or regeneration of the papilla has always been a challenge around consecutive implants or with implants next to teeth, and many studies have evaluated the papilla’s behaviour and patterns based on surgical technique and prosthetic design, though evidence about its behaviour around zirconia implants is scarce. The aim of this study was to evaluate papilla behaviour between implants and teeth (tooth® implant group) and between consecutive implants (implant–implant group). Ninety patients with 122 zirconia implants (Straumann PURE Ceramic Implant) were examined at the one-year follow up. We measured the effect of the distance: first from the base of the contact point of the crowns to the contact with bone at the implant site (D1); secondly, to the contact with the bone at the neighbouring tooth or implant site (D2); and thirdly on the papillary deficit (D3). In both the tooth-implant group and the implant–implant group, D1 and D2 correlated significantly with the papillary deficit (D3), whereas D2 was the major determinant factor (Spearman’s rho = 0.60). In both groups, when D1 and D2 were <6 mm, the papilla was present every time. The papillary deficit was significantly greater in the tooth-implant group than in the implant–implant group (p = 0.048). We conclude that the ideal distance from the base of the contact point to the bone contact at the implant and to the bone contact at the adjacent tooth in both groups is <6 mm. The height of the bone on the teeth adjacent to implants has a significant impact on that of the papilla. © 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Dental Implants; Esthetics; Gingiva; Papilla; Zirconia
Introduction Patients’ demands for good aesthetic outcomes in rehabilitation with implants, particularly anteriorly, are increasing. Not only is osseointegration expected, but adequate height and quality of soft tissue around dental implants are both essential and expected. The emerging profile of the tooth, the colour and texture of the soft tissue, and the height of the facial mucosa are important factors in the aesthetics of ∗
Corresponding author. Tel.: +49 2418088258. E-mail address: [email protected] (K. Kniha).
fixed implant-retained restorations.1 Understandably, most patients do not settle for cosmetic deformities such as “black interdental triangles” with accompanying difficulties with speech or impaction of food.2 The predictable regeneration of the interproximal periimplant papilla remains a complex challenge around implants. Most studies have investigated papillary behaviour between titanium implants, and between titanium implants and teeth. Because we know of no long-term results, we do not clearly understand whether different implant materials (such as zirconium dioxide (ZrO2 )) achieve a better periimplant mucosal response than titanium. Different authors
https://doi.org/10.1016/j.bjoms.2017.11.005 0266-4356/© 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Kniha K, et al. Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants. Br J Oral Maxillofac Surg (2017), https://doi.org/10.1016/j.bjoms.2017.11.005
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have assessed components that affect the presence or absence of the interdental papilla.1–4 Peri-implant distances from the contact point of the crowns to (a) the alveolar crest, (b) the bone contact at the implant, and (c) the bone crest at the neighbouring tooth affect the height of the papilla. Delayed placement of a zirconia implant leaves a critical distance between the alveolar crest at the neighbouring tooth and the contact point of the crown that risks a visible papillary deficit of between 7–8 mm.5 However, the effect of these measures on the incidence of the papilla between adjacent zirconia implants has not to our knowledge been studied. Our aim was to evaluate the effect of vertical distances from the base of the contact point of the crowns to the bone contact at the implant (D1), and to the bone crest at the neighbouring tooth (D2), on the presence or absence of the interproximal dental papilla round zirconia implants in two groups: implanted teeth (tooth-implant group) and adjacent implants (implant–implant group).
Patients and methods The ethics committee of the University approved the protocol, and informed consent was obtained from all 90 patients who took part in the one-year follow-up assessment. This observational retrospective study was designed to comply with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Clinical research was in accordance with the Ethical Principles for Medical Research Involving Human Subjects, outlined in the Declaration of Helsinki. Patients were included during the time period August 2013–May 2015. Smokers were excluded. Zirconia ® monotype implants (Straumann PURE Ceramic Implants ® with the ZLA surface, Straumann AG, Switzerland, Basel) were used. The radiographic and clinical assessment methods were as described previously.6 All measured distances (D1–D3) are shown in Fig. 1. Measurements were made by one examiner on the mesial and distal side of each implant and included as separate cases in both groups. Each measurement was made three times using the mean value. To measure the papillary deficit (D3), a photograph was obtained at a 90◦ angle to the interdental papilla (Fig. 2A). Before the photograph was taken the lowest contact zone of the crowns was marked with a thin copper wire. The evaluation of the papillary deficit was made using the score described by Kniha et al.6 According to the papillary deficit, four groups were delineated by the papillary index: 1 = 0 mm, 2 = >0 – <0.6 mm, 3 = ≥0.6 – <2.0 mm and 4 = ≥2.0 mm deficit. In a radiographic assessment, the distances from the base of the contact point of the crowns to the bone contact at the implant (D1), and to the bone crest at the neighbouring tooth (D2), were evaluated. The tip of the papilla was marked with a mixture of dental cement (Temp Bond, Kerr, Rastatt,
Fig. 1. Diagram of measured distances from the base of the contact point to the crowns to the contact of the bone and the implant (D1); to the contact of the bone at the neighbouring tooth (D2), and to the tip of the papilla (D3).
Germany) and tungsten powder in a ratio of 1:1 and was visualised on a standard parallel dental film (Fig. 2B).7 The standard measurement was controlled in cooperation with a university clinic for prosthodontics. Statistical analysis Statistical analyses were made with the aid of the software SPSS for Windows (version 22, IBM Corp, Ehningen, Germany) and STATA 13 (StataCorp, Texas,USA). Correlation of the data was established using Spearman’s rho test. Values were considered to be “very weak” (0.00–0.19), “weak” (0.20–0.39), “moderate” (0.40–0.59), “strong” (0.60–0.79), or “very strong” (0.80–1.0).8 Student’s t test was used to assess the significance of differences between groups, and probabilities of less than 0.05 were accepted as significant.
Results Of 90 patients (48 women and 42 men; mean (range) age, 49 (20–80) years), 73 patients had 78 single gap implants and 17 patients had 44 adjacent implants. The tooth −implant group was compared with the implant–implant one (Table 1). In the tooth–implant group, there was a moderate correlation between the distances from the alveolar crest at the implant to the base of the contact point D1 and the papillary deficit (index: 1 green = 0 mm, 2 light blue = >0 to <0.6 mm, 3 blue = ≥0.6 to <2.0 mm, and 4 red = ≥2.0 mm) (Spearman’s rho = 0.48, p = 0.000). The length of D1 ranged from 2–14 mm. When D1 was <6 mm, the papilla was present every time (index 1).
Please cite this article in press as: Kniha K, et al. Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants. Br J Oral Maxillofac Surg (2017), https://doi.org/10.1016/j.bjoms.2017.11.005
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Table 1 Overview of positions of all implants (n = 122). Position of implant
No of implants
Position of implant
No of implants
17 16 15 14 13 12 11 21 22 23 24 25 26 27
– – 5 2 – 20 22 18 24 4 6 5 – –
47 46 45 44 43 42 41 31 32 33 34 35 36 37
– – 4 5 – – – – 2 – 2 3 – –
D2 and D3. When D2 was at 7 mm length in the tooth-implant group, in some cases the papillary deficit was visible (papillary index 1–3). The papillary index increased with increasing D2 in both groups (Table 2). The papillary deficit D3 was evaluated for both groups (Table 3), and that between two implants was significantly smaller (p = 0.048). The results of Student’s t test showed no significant differences between the two groups in the mean values of D1 and D2; the only significant difference (p = 0.01) was in D1 with a papillary index of 2.
Discussion
Fig. 2. (A) Implant restorations in position 22 after one year of function. Clinical image with copper wires. (B) Radiographic implant control at position 22 with radiographic mixtures on the tip of the papilla.
Similarly, in the implant–implant group, there was a moderate correlation (Spearman’s rho = 0.48, p = 0.004) between D1 and D3, whereas D1 ranged from 4–10 mm without any papillary deficit of ≥2 mm. The papillary index increased with increasing D1 in both groups. When D1 was 10 mm long in the implant–tooth group, in some cases a papillary deficit was visible (papillary index 1–3). The papilla was present every time (index 1), once D2 was <6 mm. In the tooth-implant group, there was a strong correlation (Spearman’s rho = 0.60, P = 0.000) between the distances from the alveolar crest at the neighbouring tooth to the base of the contact point of the crowns (D2) and the papillary deficit (D3). However, the implant–implant group showed a moderate correlation (Spearman’s rho = 0.40, p = 0.012) between
Our results include two important findings about zirconia implants. First, and most importantly, for both adjacent implants and single-tooth implants, the papillary deficit correlated with the two vertical distances (D1 and D2), and D2 was the most important factor. Secondly, the papillary deficit between the two implants was significantly smaller than between an implant and a tooth. We evaluated vertical peri-implant dimensions between adjacent implants and between a tooth and an implant. The contact point of the crowns is more a contact area.9 Clinically, the lowest interdental contact point is hardly visible as it is hidden relatively deep within the interdental space. We therefore used a wire loop for marking the lowest point of the contact area. Several studies have analysed the impact of the distances from the bone contact at the implant to the base of the contact point of the crowns (D1) and from the bone contact at the neighbouring tooth or adjacent implant to the base of the contact point of the crowns (D2) on the papillary height.1,2,10 Kan et al found in 45 patients with 45 single-tooth implants that the peri-implant papillary height is independent of the proximal amount of bone next to the implant but is related to the interproximal bone next to the adjacent teeth.1 Palmer
Please cite this article in press as: Kniha K, et al. Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants. Br J Oral Maxillofac Surg (2017), https://doi.org/10.1016/j.bjoms.2017.11.005
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Table 2 Presence or absence of interproximal papilla according to the papillary index. Number of measurements and mean (SD) values of and D1 and D2 (distance from the base of the contact point to the bone crest at the adjacent tooth/implant) for the two groups. Score
1 2 3 4 Total
Distance 1 (mm)
Distance 2 (mm)
Tooth-implant
Implant–implant
No
Mean (SD)
No
Mean (SD)
71 17 58 26 172
6.4 (0.1) 7.3 (1.6) 7.9 (1.8) 9.3 (1.9) 7.8 (1.9)
14 8 18 – 40
5.7 (1.8) 5.5 (0.8) 7.1 (1.5) – 6.1 (1.7)
Tooth-implant
Implant–implant
p value
No
Mean (SD)
No
Mean (SD)
p value
0.10 0.01 0.08
66 16 58 26 166
4.7 (1.2) 4.8 (0.5) 5.7 (1.3) 7.7 (1.8) 5.7 (1.6)
12 8 18 – 38
4.4 (0.9) 4.5 (0.5) 5.5 (1.3) – 4.8 (1.1)
0.55 0.44 0.45
0.10
0.34
No = Number of areas examined. Table 3 Number of assessments and mean values of D3 (papillary deficit) for the two groups. Papillary deficit (mm)
Implant-tooth (n = 172)
Implant–implant (n = 40)
p value
Mean (SD)
0.8 (1.1)
0.5 (0.5)
0.048
et al presented data about 66 single-tooth Astra Tech Implant SystemsTM that showed a deficient papilla in correlation with D1 of over 5.9 mm.2 When D1 exceeded 8.6 mm, the papilla was no longer fully present. Our data are in line with their findings, as the critical distance D1 for a visible papillary deficit of ≥2 mm in the tooth-implant group was 6 mm but, if it exceeded 8 mm, regeneration of the papilla was no longer predictable. No comparable data are currently available for the implant–implant group. Other studies have reported measurements around adjacent implants but evaluated other distances from the top of the inter-implant bone crest to the contact point of the crowns that were not comparable with our data.4,11–15 We have shown that when the vertical distance between a single gap and adjacent implants is <6 mm, the papilla is present every time. Tarnow et al concluded that clinicians should proceed with great caution when placing adjacent implants, particularly in the aesthetic zone.13 In most cases, only about 3.4 mm interdental soft tissue can be expected over the inter-implant crest of bone around titanium implants. However, we found that the incidence of the papilla between two ZrO2 implants was greater than in the group of toothimplants. The mean (SD) interproximal papilla height with 6.1 (1.7) mm of D1 and 4.8 (1.1) of D2 did not agree with the findings of Tarnow et al. In a cross-sectional study comprising 150 patients with 100 implant restorations, Cosyn et al showed that the reestablishment of the interdental papilla is difficult when no tooth is involved.16 To recreate the interdental soft tissue, an adequate volume of bone, the right thickness of soft tissue, and aesthetic-looking restorations are necessary.17 As no papillary deficit of ≥2 mm was measured in the implant–implant group, our results indicate that papillary regeneration even between two ZrO2 implants is possible. Unfortunately the groups studied were not perfectly bal-
anced, and we need prospective, randomised studies with a control group.
Conclusion To assure the presence of the papilla, the ideal vertical distances D1 and D2 should be <6 mm between adjacent implants and between tooth and implant. Papillary deficits around adjacent ceramic implants are smaller than around single-tooth implants.
Conflict of interest We have no conflict of interest.
Ethics statement/confirmation of patients’ permission Ethics approval was obtained, and all clinical research was in accordance with the Ethical Principles for Medical Research Involving Human Subjects, outlined in the Declaration of Helsinki. Patients’ permission was also obtained.
References 1. Kan JY, Rungcharassaeng K, Umezu K, et al. Dimensions of peri-implant mucosa: an evaluation of maxillary anterior single implants in humans. J Periodontol 2003;74:557–62. 2. Palmer RM, Farkondeh N, Palmer PJ, et al. Astra Tech single-tooth implants: an audit of patient satisfaction and soft tissue form. J Clin Periodontol 2007;34:633–8. 3. Choquet V, Hermans M, Adriaenssens P, et al. Clinical and radiographic evaluation of the papilla level adjacent to single-tooth dental implants. A retrospective study in the maxillary anterior region. J Periodontol 2001;72:1364–71.
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4. Grunder U. Stability of the mucosal topography around single-tooth implants and adjacent teeth: 1-year results. Int J Periodontics Restorative Dent 2000;20:11–7. 5. Kniha K, Kniha H, Mohlhenrich SC, et al. Papilla and alveolar crest levels in immediate versus delayed single-tooth zirconia implants. Int J Oral Maxillofac Surg 2017;46:1039–44. 6. Kniha K, Gahlert M, Hicklin S, et al. Evaluation of hard and soft tissue dimensions around zirconium oxide implant-supported crowns: A 1-year retrospective study. J Periodontol 2016;87:511–8. 7. Kniha K, Mohlhenrich SC, Peters F, et al. Comparison of non-invasive radiographic measurements of soft tissue in the interdental space: a cadaver study. Br J Oral Maxillofac Surg 2017;55:482–7. 8. Prion S, Haerling KA. Making sense of methods and measurement: Spearman-rho ranked-order correlation coefficient. Clin Simul Nurs 2014;10:535–6. 9. Stappert CF, Tarnow DP, Tan JH, et al. Proximal contact areas of the maxillary anterior dentition. Int J Periodontics Restorative Dent 2010;30:471–7. 10. Schropp L, Isidor F. Papilla dimension and soft tissue level after early vs. delayed placement of single-tooth implants: 10-year results from a randomized controlled clinical trial. Clin Oral Implants Res 2015;26:278–86.
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11. Gastaldo JF, Cury PR, Sendyk WR. Effect of the vertical and horizontal distances between adjacent implants and between a tooth and an implant on the incidence of interproximal papilla. J Periodontol 2004;75:1242–6. 12. Kourkouta S, Dedi KD, Paquette DW, et al. Interproximal tissue dimensions in relation to adjacent implants in the anterior maxilla: clinical observations and patient aesthetic evaluation. Clin Oral Implants Res 2009;20:1375–85. 13. Tarnow D, Elian N, Fletcher P, et al. Vertical distance from the crest of bone to the height of the interproximal papilla between adjacent implants. J Periodontol 2003;74:1785–8. 14. Degidi M, Novaes Jr AB, Nardi D, et al. Outcome analysis of immediately placed, immediately restored implants in the esthetic area: the clinical relevance of different interimplant distances. J Periodontol 2008;79:1056–61. 15. de Oliveira RR, Novaes Jr AB, Papalexiou V, et al. Influence of interimplant distance on papilla formation and bone resorption: a clinicalradiographic study in dogs. J Oral Implantol 2006;32:218–27. 16. Cosyn J, Raes M, Packet M, et al. Disparity in embrasure fill and papilla height between tooth- and implant-borne fixed restorations in the anterior maxilla: a cross-sectional study. J Clin Periodontol 2013;40:728–33. 17. Zetu L, Wang HL. Management of inter-dental/inter-implant papilla. J Clin Periodontol 2005;32:831–9.
Please cite this article in press as: Kniha K, et al. Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants. Br J Oral Maxillofac Surg (2017), https://doi.org/10.1016/j.bjoms.2017.11.005
No. of Pages 5
ARTICLE IN PRESS Available online at www.sciencedirect.com
ScienceDirect British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx
Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants K. Kniha a,∗ , A. Modabber a , H. Kniha b , S.C. Möhlhenrich c , F. Hölzle a , S. Milz d a
Department of Oral and Cranio-Maxillofacial Surgery, University Hospital Aachen, Pauwelsstraße 30, Aachen 52074, Germany Private Dental Clinic Drs Kniha and Gahlert, Theatinerstraße 1, Munich 80333, Germany c Department of Orthodontics, University Hospital Aachen, Pauwelsstraße 30, 52074, Germany d Department of Anatomy Munich, Ludwig-Maximilians University Munich, Pettenkoferstr. 11, 80336, Germany b
Accepted 10 November 2017
Abstract Preservation or regeneration of the papilla has always been a challenge around consecutive implants or with implants next to teeth, and many studies have evaluated the papilla’s behaviour and patterns based on surgical technique and prosthetic design, though evidence about its behaviour around zirconia implants is scarce. The aim of this study was to evaluate papilla behaviour between implants and teeth (tooth® implant group) and between consecutive implants (implant–implant group). Ninety patients with 122 zirconia implants (Straumann PURE Ceramic Implant) were examined at the one-year follow up. We measured the effect of the distance: first from the base of the contact point of the crowns to the contact with bone at the implant site (D1); secondly, to the contact with the bone at the neighbouring tooth or implant site (D2); and thirdly on the papillary deficit (D3). In both the tooth-implant group and the implant–implant group, D1 and D2 correlated significantly with the papillary deficit (D3), whereas D2 was the major determinant factor (Spearman’s rho = 0.60). In both groups, when D1 and D2 were <6 mm, the papilla was present every time. The papillary deficit was significantly greater in the tooth-implant group than in the implant–implant group (p = 0.048). We conclude that the ideal distance from the base of the contact point to the bone contact at the implant and to the bone contact at the adjacent tooth in both groups is <6 mm. The height of the bone on the teeth adjacent to implants has a significant impact on that of the papilla. © 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Dental Implants; Esthetics; Gingiva; Papilla; Zirconia
Introduction Patients’ demands for good aesthetic outcomes in rehabilitation with implants, particularly anteriorly, are increasing. Not only is osseointegration expected, but adequate height and quality of soft tissue around dental implants are both essential and expected. The emerging profile of the tooth, the colour and texture of the soft tissue, and the height of the facial mucosa are important factors in the aesthetics of ∗
Corresponding author. Tel.: +49 2418088258. E-mail address: [email protected] (K. Kniha).
fixed implant-retained restorations.1 Understandably, most patients do not settle for cosmetic deformities such as “black interdental triangles” with accompanying difficulties with speech or impaction of food.2 The predictable regeneration of the interproximal periimplant papilla remains a complex challenge around implants. Most studies have investigated papillary behaviour between titanium implants, and between titanium implants and teeth. Because we know of no long-term results, we do not clearly understand whether different implant materials (such as zirconium dioxide (ZrO2 )) achieve a better periimplant mucosal response than titanium. Different authors
https://doi.org/10.1016/j.bjoms.2017.11.005 0266-4356/© 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Kniha K, et al. Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants. Br J Oral Maxillofac Surg (2017), https://doi.org/10.1016/j.bjoms.2017.11.005
YBJOM-5299;
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have assessed components that affect the presence or absence of the interdental papilla.1–4 Peri-implant distances from the contact point of the crowns to (a) the alveolar crest, (b) the bone contact at the implant, and (c) the bone crest at the neighbouring tooth affect the height of the papilla. Delayed placement of a zirconia implant leaves a critical distance between the alveolar crest at the neighbouring tooth and the contact point of the crown that risks a visible papillary deficit of between 7–8 mm.5 However, the effect of these measures on the incidence of the papilla between adjacent zirconia implants has not to our knowledge been studied. Our aim was to evaluate the effect of vertical distances from the base of the contact point of the crowns to the bone contact at the implant (D1), and to the bone crest at the neighbouring tooth (D2), on the presence or absence of the interproximal dental papilla round zirconia implants in two groups: implanted teeth (tooth-implant group) and adjacent implants (implant–implant group).
Patients and methods The ethics committee of the University approved the protocol, and informed consent was obtained from all 90 patients who took part in the one-year follow-up assessment. This observational retrospective study was designed to comply with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Clinical research was in accordance with the Ethical Principles for Medical Research Involving Human Subjects, outlined in the Declaration of Helsinki. Patients were included during the time period August 2013–May 2015. Smokers were excluded. Zirconia ® monotype implants (Straumann PURE Ceramic Implants ® with the ZLA surface, Straumann AG, Switzerland, Basel) were used. The radiographic and clinical assessment methods were as described previously.6 All measured distances (D1–D3) are shown in Fig. 1. Measurements were made by one examiner on the mesial and distal side of each implant and included as separate cases in both groups. Each measurement was made three times using the mean value. To measure the papillary deficit (D3), a photograph was obtained at a 90◦ angle to the interdental papilla (Fig. 2A). Before the photograph was taken the lowest contact zone of the crowns was marked with a thin copper wire. The evaluation of the papillary deficit was made using the score described by Kniha et al.6 According to the papillary deficit, four groups were delineated by the papillary index: 1 = 0 mm, 2 = >0 – <0.6 mm, 3 = ≥0.6 – <2.0 mm and 4 = ≥2.0 mm deficit. In a radiographic assessment, the distances from the base of the contact point of the crowns to the bone contact at the implant (D1), and to the bone crest at the neighbouring tooth (D2), were evaluated. The tip of the papilla was marked with a mixture of dental cement (Temp Bond, Kerr, Rastatt,
Fig. 1. Diagram of measured distances from the base of the contact point to the crowns to the contact of the bone and the implant (D1); to the contact of the bone at the neighbouring tooth (D2), and to the tip of the papilla (D3).
Germany) and tungsten powder in a ratio of 1:1 and was visualised on a standard parallel dental film (Fig. 2B).7 The standard measurement was controlled in cooperation with a university clinic for prosthodontics. Statistical analysis Statistical analyses were made with the aid of the software SPSS for Windows (version 22, IBM Corp, Ehningen, Germany) and STATA 13 (StataCorp, Texas,USA). Correlation of the data was established using Spearman’s rho test. Values were considered to be “very weak” (0.00–0.19), “weak” (0.20–0.39), “moderate” (0.40–0.59), “strong” (0.60–0.79), or “very strong” (0.80–1.0).8 Student’s t test was used to assess the significance of differences between groups, and probabilities of less than 0.05 were accepted as significant.
Results Of 90 patients (48 women and 42 men; mean (range) age, 49 (20–80) years), 73 patients had 78 single gap implants and 17 patients had 44 adjacent implants. The tooth −implant group was compared with the implant–implant one (Table 1). In the tooth–implant group, there was a moderate correlation between the distances from the alveolar crest at the implant to the base of the contact point D1 and the papillary deficit (index: 1 green = 0 mm, 2 light blue = >0 to <0.6 mm, 3 blue = ≥0.6 to <2.0 mm, and 4 red = ≥2.0 mm) (Spearman’s rho = 0.48, p = 0.000). The length of D1 ranged from 2–14 mm. When D1 was <6 mm, the papilla was present every time (index 1).
Please cite this article in press as: Kniha K, et al. Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants. Br J Oral Maxillofac Surg (2017), https://doi.org/10.1016/j.bjoms.2017.11.005
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ARTICLE IN PRESS K. Kniha et al. / British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx
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Table 1 Overview of positions of all implants (n = 122). Position of implant
No of implants
Position of implant
No of implants
17 16 15 14 13 12 11 21 22 23 24 25 26 27
– – 5 2 – 20 22 18 24 4 6 5 – –
47 46 45 44 43 42 41 31 32 33 34 35 36 37
– – 4 5 – – – – 2 – 2 3 – –
D2 and D3. When D2 was at 7 mm length in the tooth-implant group, in some cases the papillary deficit was visible (papillary index 1–3). The papillary index increased with increasing D2 in both groups (Table 2). The papillary deficit D3 was evaluated for both groups (Table 3), and that between two implants was significantly smaller (p = 0.048). The results of Student’s t test showed no significant differences between the two groups in the mean values of D1 and D2; the only significant difference (p = 0.01) was in D1 with a papillary index of 2.
Discussion
Fig. 2. (A) Implant restorations in position 22 after one year of function. Clinical image with copper wires. (B) Radiographic implant control at position 22 with radiographic mixtures on the tip of the papilla.
Similarly, in the implant–implant group, there was a moderate correlation (Spearman’s rho = 0.48, p = 0.004) between D1 and D3, whereas D1 ranged from 4–10 mm without any papillary deficit of ≥2 mm. The papillary index increased with increasing D1 in both groups. When D1 was 10 mm long in the implant–tooth group, in some cases a papillary deficit was visible (papillary index 1–3). The papilla was present every time (index 1), once D2 was <6 mm. In the tooth-implant group, there was a strong correlation (Spearman’s rho = 0.60, P = 0.000) between the distances from the alveolar crest at the neighbouring tooth to the base of the contact point of the crowns (D2) and the papillary deficit (D3). However, the implant–implant group showed a moderate correlation (Spearman’s rho = 0.40, p = 0.012) between
Our results include two important findings about zirconia implants. First, and most importantly, for both adjacent implants and single-tooth implants, the papillary deficit correlated with the two vertical distances (D1 and D2), and D2 was the most important factor. Secondly, the papillary deficit between the two implants was significantly smaller than between an implant and a tooth. We evaluated vertical peri-implant dimensions between adjacent implants and between a tooth and an implant. The contact point of the crowns is more a contact area.9 Clinically, the lowest interdental contact point is hardly visible as it is hidden relatively deep within the interdental space. We therefore used a wire loop for marking the lowest point of the contact area. Several studies have analysed the impact of the distances from the bone contact at the implant to the base of the contact point of the crowns (D1) and from the bone contact at the neighbouring tooth or adjacent implant to the base of the contact point of the crowns (D2) on the papillary height.1,2,10 Kan et al found in 45 patients with 45 single-tooth implants that the peri-implant papillary height is independent of the proximal amount of bone next to the implant but is related to the interproximal bone next to the adjacent teeth.1 Palmer
Please cite this article in press as: Kniha K, et al. Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants. Br J Oral Maxillofac Surg (2017), https://doi.org/10.1016/j.bjoms.2017.11.005
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Table 2 Presence or absence of interproximal papilla according to the papillary index. Number of measurements and mean (SD) values of and D1 and D2 (distance from the base of the contact point to the bone crest at the adjacent tooth/implant) for the two groups. Score
1 2 3 4 Total
Distance 1 (mm)
Distance 2 (mm)
Tooth-implant
Implant–implant
No
Mean (SD)
No
Mean (SD)
71 17 58 26 172
6.4 (0.1) 7.3 (1.6) 7.9 (1.8) 9.3 (1.9) 7.8 (1.9)
14 8 18 – 40
5.7 (1.8) 5.5 (0.8) 7.1 (1.5) – 6.1 (1.7)
Tooth-implant
Implant–implant
p value
No
Mean (SD)
No
Mean (SD)
p value
0.10 0.01 0.08
66 16 58 26 166
4.7 (1.2) 4.8 (0.5) 5.7 (1.3) 7.7 (1.8) 5.7 (1.6)
12 8 18 – 38
4.4 (0.9) 4.5 (0.5) 5.5 (1.3) – 4.8 (1.1)
0.55 0.44 0.45
0.10
0.34
No = Number of areas examined. Table 3 Number of assessments and mean values of D3 (papillary deficit) for the two groups. Papillary deficit (mm)
Implant-tooth (n = 172)
Implant–implant (n = 40)
p value
Mean (SD)
0.8 (1.1)
0.5 (0.5)
0.048
et al presented data about 66 single-tooth Astra Tech Implant SystemsTM that showed a deficient papilla in correlation with D1 of over 5.9 mm.2 When D1 exceeded 8.6 mm, the papilla was no longer fully present. Our data are in line with their findings, as the critical distance D1 for a visible papillary deficit of ≥2 mm in the tooth-implant group was 6 mm but, if it exceeded 8 mm, regeneration of the papilla was no longer predictable. No comparable data are currently available for the implant–implant group. Other studies have reported measurements around adjacent implants but evaluated other distances from the top of the inter-implant bone crest to the contact point of the crowns that were not comparable with our data.4,11–15 We have shown that when the vertical distance between a single gap and adjacent implants is <6 mm, the papilla is present every time. Tarnow et al concluded that clinicians should proceed with great caution when placing adjacent implants, particularly in the aesthetic zone.13 In most cases, only about 3.4 mm interdental soft tissue can be expected over the inter-implant crest of bone around titanium implants. However, we found that the incidence of the papilla between two ZrO2 implants was greater than in the group of toothimplants. The mean (SD) interproximal papilla height with 6.1 (1.7) mm of D1 and 4.8 (1.1) of D2 did not agree with the findings of Tarnow et al. In a cross-sectional study comprising 150 patients with 100 implant restorations, Cosyn et al showed that the reestablishment of the interdental papilla is difficult when no tooth is involved.16 To recreate the interdental soft tissue, an adequate volume of bone, the right thickness of soft tissue, and aesthetic-looking restorations are necessary.17 As no papillary deficit of ≥2 mm was measured in the implant–implant group, our results indicate that papillary regeneration even between two ZrO2 implants is possible. Unfortunately the groups studied were not perfectly bal-
anced, and we need prospective, randomised studies with a control group.
Conclusion To assure the presence of the papilla, the ideal vertical distances D1 and D2 should be <6 mm between adjacent implants and between tooth and implant. Papillary deficits around adjacent ceramic implants are smaller than around single-tooth implants.
Conflict of interest We have no conflict of interest.
Ethics statement/confirmation of patients’ permission Ethics approval was obtained, and all clinical research was in accordance with the Ethical Principles for Medical Research Involving Human Subjects, outlined in the Declaration of Helsinki. Patients’ permission was also obtained.
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Please cite this article in press as: Kniha K, et al. Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants. Br J Oral Maxillofac Surg (2017), https://doi.org/10.1016/j.bjoms.2017.11.005