Submission to Journal of Clinical Periodontology: CPE-12-12-4284.R2

TITLE

Disparity in embrasure fill and papilla height between tooth- and implant-borne fixed restorations in the

anterior maxilla: a cross-sectional study

RUNNING TITLE

Embrasure fill and papilla height

KEY WORDS

Dental implant, tooth, fixed partial denture, embrasure, papilla

AUTHORS

Cosyn, J., Raes, M., Packet, M., Cleymaet, R., De Bruyn, H.

AFFILIATIONS AND INSTITUTIONS

Jan Cosyn1,2, Magalie Raes1, Mathieu Packet3, Roberto Cleymaet2,3, Hugo De Bruyn1,4

1University of Ghent, Faculty of Medicine and Health Sciences, Dental School, Department of Periodontology

and Oral Implantology, De Pintelaan 185, B-9000 Ghent, Belgium

2Free University of Brussels (VUB), Faculty of Medicine and Pharmacy, Dental Medicine, Laarbeeklaan 103, B-

1090 Brussels, Belgium

3Private multidisciplinary practice, Ghent, Belgium

4Malmö University, Faculty of Odontology, Department of Prosthodontics, 205 06 Malmö, Sweden

CONTACT ADDRESS CORRESPONDING AUTHOR

Jan Cosyn

University of Ghent, Faculty of Medicine and Health Sciences, Dental School, Department of Periodontology

and Oral Implantology, De Pintelaan 185, B-9000 Ghent, Belgium

E-mail: jan.cosyn@ugent.be

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WORD COUNT

3003

CONFLICT OF INTERESTS AND SOURCE OF FUNDING

The authors declare they have no conflict of interests. The study was supported by the authors and their

institutions.

ABSTRACT

Purpose: The objective of the present study was to compare interproximal fill and papilla height between

different embrasures.

Material and methods: One hundred and fifty non-smoking consecutive patients (mean age 54, range 32–73;

63 males and 87 females) without periodontal disease were selected in a multidisciplinary practice during regular

supportive care. All had been treated for multiple tooth loss in the anterior maxilla at least one year earlier by

means of a fixed restoration on teeth (n = 50) or implants (n = 100) using straightforward procedures (without

hard and/or soft tissue augmentation). Embrasure fill was assessed by means of Jemt’s papilla index and papilla

height was registered following local anesthesia by means of bone sounding by one clinician.

Results: Tooth-pontic and tooth-implant embrasures demonstrated comparable interproximal fill and papilla

height (≥ 58 % Jemt’s score 3; mean papilla height ≥ 4.1 mm). Between missing teeth, embrasure fill and papilla

height were lower regardless of the embrasure type. The implant-implant and implant-pontic embrasure

demonstrated comparable outcome (≤ 42 % Jemt’s score 3; mean papilla height ≤ 3.3 mm; p ≥ 0.416), which

was significantly poorer when compared to the pontic-pontic embrasure (82 % Jemt’s score 3; mean papilla

height 3.7 mm; p ≤ 0.019). Overall, papilla index and papilla height demonstrated a weak correlation

(Spearman’s correlation coefficient: 0.198; p = 0.002).

Conclusions: The reestablishment of a papilla is difficult when there is no tooth involved. In that scenario a

short papilla should be expected and implant-borne restorations demonstrate the poorest outcome. Moreover, an

implant with a pontic may not perform better than adjacent implants.

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CLINICAL RELEVANCE

Scientific rationale: The objective of the present study was to compare interproximal fill and papilla height

between different embrasures in 150 consecutive patients with fixed restorations on teeth or implants.

Principal findings: The reestablishment of a papilla was most difficult between missing teeth. The implant-

implant and implant-pontic embrasure demonstrated comparable outcome, which was significantly poorer when

compared to the pontic-pontic embrasure.

Practical implications: An implant with a pontic may not perform better than adjacent implants in terms of

papilla presence.

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Introduction

The aesthetic outcome of a prosthetic treatment is difficult to evaluate as it may be affected by many parameters.

In a recent systematic review on the professional assessment of aesthetics in implant dentistry this complexity

was highlighted and the need for a consensus on objective and well-defined aesthetic parameters was described

(Benic et al. 2012). Albeit there is currently little agreement on such parameters, the presence of papillae may be

considered an important characteristic of an aesthetic result.

A number of studies have been published on papillae in the context of single implant treatment (Grunder 2000,

Choquet et al. 2001, Kan et al. 2003, Henriksson & Jemt 2004, Cardaropoli et al. 2006, Juodzbalys & Wang

2007, Lai et al. 2008, Chen et al. 2009, Cosyn et al. 2011, 2012a, Buser et al. 2011, den Hartog et al. 2008,

2011a,b, Gallucci et al. 2011, Raes et al. 2011). Choquet et al. (2001) described complete papilla index in 58 %

of the cases between a tooth and an implant with mean papilla height of nearly 4 mm as assessed by bone

sounding. The latter may not differ substantially from papilla height between teeth (Tarnow et al. 1992), which

has been explained by the preservation of bone and supracrestal fibers at the tooth facing the implant restoration.

Hence, factors causing loss of these tissues such as periodontal disease, multiple surgeries with papilla openings

and incorrect implant positioning in relation to the tooth, may in turn be responsible for partial or complete

papilla loss (Cosyn et al. 2012c).

A recent study has shown that a conventional bridge is still a common treatment concept for single tooth

replacement in general practice (Cosyn et al. 2012b). In this concept, the embrasure is formed by a tooth and a

pontic. The tissue preserving effect of a tooth may also apply here, which is in line with a ‘predictable papilla

length’ of about 5 mm for interproximal tooth surfaces as described by Salama and co-workers (1998). On the

other hand, data on papilla index for a tooth-pontic (T-P) embrasure are lacking. Hence, the first objective was to

compare papilla index and height between the tooth-implant (T-I) and the T-P embrasure.

Complexity increases when two adjacent teeth need replacement in the anterior maxilla. Especially the re-

establishment of a papilla between missing teeth is particularly challenging since the interdental bone peak will

flatten following tooth loss. Essentially, such an embrasure can be formed by two pontics, two implants or an

implant and a pontic. Salama and co-workers (1998) observed a ‘predictable papilla length’ of about 5 mm for

interproximal tooth surfaces, 4.5 mm between adjacent implants and 5.5 mm for interproximal implant surfaces

not facing another implant. These data suggest the most optimal papilla for an implant-pontic (I-P) and pontic-

pontic (P-P) embrasure. However, the lack of clear selection criteria and the fact that papilla length was

registered by sounding the first tooth- or implant-to-bone contact instead of the interproximal crestal bone peak,

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make a correct interpretation difficult. Tarnow and co-workers (2003) described mean papilla height of 3.4 mm

between implants as assessed by sounding the interproximal crestal bone peak on the basis of a quite

heterogeneous sample in terms of implant position (anterior as well as posterior), implant type (one- as well as

two-piece implants) and bone conditions (native as well as regenerated bone). To overcome aesthetic failures as

a result of a deficient papilla, Tarnow et al. (2003) and Barreto et al. (2008) suggested to place only one implant

instead of two and to splint it to a cantilevered ovate pontic. Interestingly however, Tymstra et al. (2011)

demonstrated identical embrasure fill for the implant-implant (I-I) and I-P embrasure. Limitations include a very

small study sample (5 patients per embrasure type) and lack of data on papilla height. This information clearly

shows that the available literature falls short when it comes to data on papillae formed by two pontics, two

implants or an implant and a pontic. Hence, another objective was to compare papilla index and height between

these embrasures. This information is important from an aesthetic point of view (Tarnow et al. 1992, Jemt 1997)

and may become one of the reasons to select or refute a prosthetic treatment option in clinical practice.

Material and Methods

Patient selection

This cross-sectional study was based on a convenience sample of 150 consecutive patients consulting for regular

supportive care in a multidisciplinary practice in Ghent between September 2009 and January 2012. Patients

were selected on the basis of specific inclusion and exclusion criteria.

Inclusion criteria were as follows:

- Fixed restoration on teeth (FRT) or implants (FRI) replacing 2 or more adjacent teeth in the anterior

maxilla (15-25) and at least 1 year in function.

- Prosthetic procedures performed by 1 of 2 restorative dentists (RC/MP).

- With respect to FRI, surgical procedures performed by 1 of 2 implant surgeons only using two-piece

implant systems (JC/MP).

- Informed consent.

Exclusion criteria were as follows:

- Systemic diseases.

- Intake of medication that could induce gingival overgrowth.

- Smoking or history of smoking.

- Prostheses without ovate pontic design.

- History of periodontal treatment.

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- Periodontal disease at the time of examination.

- Hard and/or soft tissue augmentation procedures.

- With respect to FRI, suboptimal implant position (T-I distance < 2 mm, I-I distance < 3 mm) as

clinically and/or radiographically assessed.

- With respect to FRI, peri-implant probing depth > 4 mm and/or bone loss ≥ 2 mm.

Measurements between an abutment tooth and adjacent pontic (T-P) and between pontics (P-P) were performed

in 50 patients with a FRT (Group I). Measurements between a tooth and an implant (T-I) and between adjacent

implants (I-I) were performed in 50 patients with a FRI (Group II). In another 50 patients with a FRI, papillae

were studied between an implant and a pontic (I-P) (Group III). All embrasures were evaluated in the anterior

maxilla and if the embrasure type of interest was present at multiple locations in a patient, the most central

location was selected. The study protocol was approved by the Ethical Committee of the University Hospital in

Ghent.

Outcome variables

The following outcome variables were registered for 250 embrasures with different embrasures in 150 patients

by the same experienced and calibrated clinician (JC):

- Embrasure fill was assessed by means of Jemt’s papilla index (Jemt 1997).

- Papilla height was registered following local anesthesia by means of bone sounding using a periodontal

probe (PCPUNC 15, Hu-Friedy®, Leimen, Germany) as described by Tarnow et al. (1992). All

recordings were rounded off to the nearest 0.5 mm.

Calibration for papilla index was based on 20 duplicate recordings in 4 patients with a time interval of 1 week.

Calibration for papilla height was based on a comparison of clinical height to radiographic height of 10 central

maxillary papillae in 10 patients. Radiographic papilla height was determined on the basis of digital radiographs

taken with the long-cone paralleling technique. Designated software (DBSWIN, Dürr Dental AG, Bietigheim-

Bissingen,Germany) was used to calculate radiographic papilla height. Cases used for calibration included all

embrasure types.

Statistical analysis

Data analysis was performed with the patient as the experimental unit. The majority of the data were non-

normally distributed and therefore non-parametric tests were applied. For all continuous variables (age, years in

function, papilla height) mean values and standard deviations were calculated, whereas frequency distributions

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were made for categorical variables (gender, papilla index). Disparities between patient groups in terms of age

and years in function were evaluated using the Kruskal-Wallis test. For gender, the Fisher’s exact test was

adopted. The Wilcoxon signed ranks test was used to study disparities in papilla index and papilla height

between paired data (T-P and P-P within the same patient; T-I and I-I within the same patient). The Fisher’s

exact test was adopted to compare unpaired data in terms of papilla index (T-P and T-I in different patients; P-P,

I-I and I-P in different patients). Disparities in papilla height between unpaired data were evaluated using the

Mann-Whitney test (T-P and T-I in different patients) or Kruskal-Wallis test (P-P, I-I and I-P in different

patients). The level of significance was set at 0.05 with no correction for multiple testing.

Results

The total sample included 150 patients with a mean age of 54 (range 32-73). Sixty-three were males and 87 were

females. Restorations had been on average 4 years in function (range 1-10). Table 1 gives an overview of

patient’s age, gender and years in function of the restoration per patient group. Patient groups did not differ in

any of these aspects (p ≥ 0.091). Sixty-seven patients were rehabilitated using parallel-walled Biomet 3i® (Palm

Beach, Florida, USA) implants with an external connection, 22 using tapered Biomet 3i® implants with an

internal connection and 11 using Replace Select tapered TiUnite® (Nobel Biocare, Göteborg, Sweden) implants.

(HERE APPROXIMATELY TABLE 1 PLEASE)

Embrasure fill

Duplicate registration of papilla index resulted in high intra-examiner agreement (Spearman’s correlation

coefficient: 0.915; p ≤ 0.001).

Table 2 shows frequency distributions on papilla index sorted per embrasure type. T-P and P-P embrasures

assessed in the FRT group, did not differ significantly in papilla index (p = 0.439). In the FRI group with

adjacent implants however, significantly less interproximal fill was observed for I-I when compared to T-I

embrasures (p < 0.001). Comparison of unpaired data in different patient groups revealed comparable papilla

index for T-P and T-I embrasures (p = 0.185). Particularly interesting from an aesthetic point of view was the

evaluation of papilla index between missing teeth with P-P, I-I or I-P embrasures as possible solutions.

Significantly more interproximal fill was observed for the P-P embrasure when compared to I-I (p < 0.001) and

I-P (p < 0.001). I-I and I-P embrasures demonstrated comparable papilla index (p = 0.416). As also shown in

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table 2, complete interproximal fill was only accomplished in less than half of the cases when one or two

implants formed the embrasure. A clinical example of an I-P embrasure is shown in figure 1.

(HERE APPROXIMATELY TABLE 2 & FIGURE 1 PLEASE)

Papilla height

Clinical and radiographic papilla height demonstrated high agreement (Spearman’s correlation coefficient:

0.994; p ≤ 0.001). Based on the total patient sample papilla height and years in function demonstrated a

significant, yet weak correlation (Spearman’s correlation coefficient: 0.178; p = 0.029).

Table 3 shows the results on papilla height sorted per embrasure type. T-P and P-P embrasures as assessed in the

FRT group, differed significantly in papilla height with papillae being on average 0.5 mm shorter between

pontics (p = 0.001). In the FRI group with adjacent implants, papillae were on average 0.8 mm shorter for I-I

when compared to T-I embrasures (p < 0.001). Comparison of unpaired data in different patient groups revealed

comparable papilla height for T-P and T-I embrasures (p = 0.383). When scrutinizing possible solutions for

recreating papillae between missing teeth, papillae were on average 0.4 – 0.5 mm higher for the P-P embrasure

when compared to I-I (p = 0.019) and I-P (p = 0.004). I-I and I-P embrasures demonstrated comparable papilla

height (p = 0.486). As also shown in table 3, the probability of ending up with an ideal papilla (≥ 4 mm) between

missing teeth was reduced by half when one or two implants formed the embrasure.

(HERE APPROXIMATELY TABLE 3 PLEASE)

Correlation of papilla index with papilla height

On the basis of the total sample (n = 250) papilla index and papilla height demonstrated a weak, yet significant

correlation (Spearman’s correlation coefficient: 0.198; p = 0.002).

Discussion

The amount of soft tissues filling the embrasure may be affected by ample factors. These have been identified in

a study on single implant treatment using multivariate analyses and include periodontal disease, multiple

surgeries with papilla openings and factors relating to the implant and contact point position (Cosyn et al.

2012c). In the present study patient selection was very strict taking into account most of these factors. Albeit this

stringent intake took many years, it ensured a quite homogeneous study sample allowing for comparisons of

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multiple embrasures in different patient groups. Salama and co-workers (1998) were the first to document

‘predictable papilla length’ for different embrasures. However, their findings are difficult to interpret given the

lack of clear selection criteria and the fact that papilla length was registered by sounding the first tooth- or

implant-to-bone contact instead of the interproximal crestal bone peak. Clearly, accurate data on papillae for

different embrasures are needed as these may be important from an aesthetic point of view.

A key finding was that the T-I and T-P embrasure demonstrated similar papilla index (≥ 58 % with complete fill)

and papilla height (≥ 4.1 mm on average). These data do not differ substantially from those between teeth

(Tarnow et al. 1992), suggesting a tissue preserving effect of the tooth. On the other hand, when the embrasure

was not formed by a tooth significantly less embrasure fill and/or papilla height were found. This situation

occurs when adjacent teeth are missing and need replacement. The most favourable outcome was found when

such an embrasure was formed by two pontics (82 % with complete fill and 3.7 mm mean papilla height).

Whenever one or two implants formed such an embrasure, significantly less embrasure fill (≤ 42 % with

complete fill) and papilla height (≤ 3.3 mm on average) were demonstrated. Tarnow et al. (2003) described mean

papilla height of 3.4 mm between implants, which is very similar to our observation (3.3 mm on average).

Interestingly, the I-P embrasure did not perform better than the I-I embrasure in contrast to previous beliefs

(Tarnow et al. 2003, Barreto et al. 2008), which is in agreement with a recent pilot study (Tymstra et al. 2011).

This information is clinically relevant when it comes to replacing two missing adjacent teeth in the anterior

maxilla. The installation of only one implant with a cantilevered pontic is less expensive than two implants, but

may not result in superior aesthetics as shown in this study. Moreover, clinicians should be aware of the fact that

there are only limited data on implant success and complications for a cantilever bridge on only one implant

(Aglietta et al. 2009, 2012, Tymstra et al. 2011).

By and large, about 1 mm shorter papillae were demonstrated between implants or between an implant and a

pontic when compared to embrasures formed by one or two teeth. Possibly this is related to a lack of inserting

supracrestal fibers around implants (Berglundh et al. 1991). In addition, one may also expect significant loss in

the vertical dimension in such embrasures since the bone peak will flatten following tooth extraction. The

papillary asymmetry may therefore even become 2 mm as described by Kourkouta et al. (2009), which is

detrimental from an aesthetic point of view when a central and lateral incisor or a lateral incisor and a cuspid on

one side need replacement. Ridge preservation, orthodontic extrusion, bone augmentation, distraction

osteogenesis and root submergence have been proposed as treatment options (Zetu & Wang 2005, Salama et al.

2007). Given the technical complexity of these concepts and their single focus on bone foundation, it is clear that

9

implant dentistry has no straightforward solution for this problem and a FRT with a P-P embrasure may be

considered the best option from an aesthetic point of view to treat this. On the other hand, the range on papilla

height for a P-P embrasure was very high in this study and one could question whether it is ethical to remove

sound tooth structure in order to install a FRT. Future studies should therefore focus on papilla reconstruction

between implants or between an implant and a pontic using connective tissue grafting. Since it is also unclear

whether further improvement in the papilla formed by two pontics is possible using connective tissue grafting,

prospective studies should also focus on FRT.

In this study the papilla index by Jemt (1997) was used to study embrasure fill. As this index was initially

designed for single tooth implants with adjacent teeth, it may not really hold up when there is no tooth forming

the embrasure, i.e. between pontics, beween adjacent implants or between an implant and a pontic. In these

situations, the two adjacent crowns can be made to any shape to close down the embrasure space resulting in a

high papilla index score whereas papilla height may remain low. This phenomenon may explain why the P-P

embrasure demonstrated complete fill in 82 % of the cases, whereas mean papilla height was only 3.7 mm.

Hence, it is not surprising that papilla index and papilla height only demonstrated a weak correlation. Clearly,

the results on papilla height may be considered crucial in this study and papilla index data should be interpreted

with caution as these may be prone to bias. A second limitation of this study relates to the fact that T-T

embrasures were not included. On the other hand, it was our objective to study embrasures in the context of

different treatment options for tooth loss and these do not include T-T embrasures. Another concern of this study

relates to the bone sounding technique and the associated risk of soft tissue damage. Because of this, imaging

techniques may be preferred in future studies. However, an important limitation of these methods is a lack of

visibility of the tip of the papilla due to overlap of teeth. This is especially the case in the canine and premolar

region and was the very reason why we only included digital radiographs of the central papilla to evaluate

accuracy of clinical registrations. A final concern of this study relates to the external validity of the results. An

attempt was made to select a homogeneous sample in terms of clinicians, periodontal and peri-implant

conditions, implant types and positions, and pontic design. However, more factors may affect the presence of a

papilla (Chang 2007, Chow et al. 2010), and the impact of socio-economic and geographic aspects remains to be

investigated.

In conclusion, this clinical study showed that the reestablishment of a papilla is difficult when there is no tooth

involved. In that scenario a short papilla should be expected and implant-borne restorations demonstrate the

poorest outcome. Moreover, an implant with a pontic may not perform better than adjacent implants.

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Acknowledgements

The authors wish to thank all participants for their contribution.

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