Single Restorations in the Resorbed Posterior Mandible Supported by 6-mm Implants: A 1-Year Prospective Case Series Study Felix L Guljé, DDS;*,† Gerry M Raghoebar, DDS, MD, PhD;‡ Arjan Vissink, DDS, MD, PhD;‡ Henny JA Meijer, DDS, PhD‡,§

ABSTRACT Purpose: The aim of this prospective case series study was to assess the clinical performance of single restorations in the posterior mandible supported by 6-mm implants. Materials and Methods: Twenty-one consecutive patients with one or more missing premolars or molars in the posterior mandible and with an estimated bone height of 8 mm between the top of the ridge and alveolar nerve were included. Each patient was to receive one or more 6-mm implants (OsseoSpeed 4.0 S, Astra Tech Implant System, Dentsply Implants, Mölndal, Sweden) without any grafting. After a 3-month osseointegration period, the implants were restored with custommade titanium abutments (Atlantis abutment, Dentsply Implants) and cemented zirconia-based porcelain crowns. Clinical and radiographic examinations were performed at placement of the restoration and 12 months thereafter. Next to this, patients’ satisfaction was scored before treatment and after 12 months with the restoration in function. Results: Implant survival was 100%. From loading to the 12-month follow-up, mean marginal bone loss was 0.14 mm (SD: 0.4). Mean scores for plaque, calculus, gingiva, bleeding, and pocket probing depth were low. Patients’ satisfaction was high. Conclusion: One-year follow-up data revealed that 6-mm dental implants inserted in the resorbed posterior mandible provide a solid basis for single tooth restoration. KEY WORDS: posterior mandible, prospective study, short dental implants, single restorations

INTRODUCTION

cient bone height above the mandibular nerve. Surgical reconstruction of a planned implant site by vertical bone grafting techniques can be a solution. However, complications, especially for vertical augmentation, are common.1 Adaptation of the implant to the existing anatomy through the use of shorter implants can serve as an alternative procedure reducing the number and complexity of surgical treatment procedures, treatment time, and morbidity. Short implants have been reported with high success rates. The survival rates of implants of 0.5 until 1.0

n = 31

−0.14 mm (0.42) 3 (9.6) 1 (3.2) 25 (80.6) 1 (3.2) 1 (3.2)

period 0–2 years) of Fugazzotto17; and 100% (70 implants) in a prospective study of Guljé and colleagues13 with a 1-year evaluation period. However, in the latter study, subjects were randomly allocated to receiving implants with lengths of either 6 or 11 mm. In all cases, there had to be sufficient bone height to allow placement of an implant of at least 11 mm in length. Next to this, two or three adjacent implants were placed per subject and restored with splinted restorations. In the present study, there was a limited bone height and nonsplinted restorations. The survival rate of 100% of the 6-mm implants in the present study is consistent with the percentages of the mentioned clinical studies.

The mean scores on the indices for plaque, calculus, gingiva, and bleeding were very low at the 1-year evaluation. The scores are comparable with the 1-year studies on short implants in the posterior region of Telleman and colleagues11,12 in which the same criteria were used. The strict oral hygiene regime to which patients were subjected provided healthy periimplant tissues, with the mean probing depth of 2.5 mm. This depth was not different to what has been reported in another study evaluating 6-mm implants13 and is accompanied with healthy peri-implant soft tissues. There was only limited bone loss (mean value of 0.14 mm) during the functional 1-year period. A comparable limited bone loss was found in an earlier study by Guljé and colleagues13 in which the same implant system was used. Apparently, the close connection with platform switch of implant and abutment, together with an optimum surface roughness at the neck of the implant, provides a stable peri-implant marginal bone level. This is consistent with the favorable results of platform switching in the study of Telleman and colleagues.11,12 There was a significant difference in patients’ satisfaction between the pretreatment situation and at T12. Feelings of shame for the visibility of being partial

TABLE 4 Patient’s Satisfaction before Treatment and after 12 Months and Significant Differences between Time Periods

Feelings Presence of shame Self-confidence decreased Visible being partial edentulous Function Evade eating with the edentulous zone/implant The ability to chew is decreased Implant does influence the speech Implant does influence the taste Aesthetics Not satisfied with the color of the crown Not satisfied with the form of the crown Not satisfied with the color of the mucosa around the crown Not satisfied with the form of the mucosa around the crown Overall satisfaction (0–10)

5

Tpre % in Agreement

T12 % in Agreement

(n = 21)

(n = 21)

19.4 19.4 25.8

0.0* 0.0* 0.0*

80.6 83.9 — —

3.2* 3.2* 0.0 0.0

— — — — 5.6 1 1.5

0.0 0.0 0.0 0.0 9.3 1 0.9*

*Significant differences compared with pretreatment values (Wilcoxon signed-rank test; p = .000–.003).

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Clinical Implant Dentistry and Related Research, Volume *, Number *, 2014

edentulous decreased. Patients were significantly more satisfied with chewing. The scores were comparable with the 1-year studies on short implants in the posterior region by Telleman and colleagues11,12 in which the same questionnaires were used. Restorations of considerable height are needed on short implants in a severely resorbed mandible, resulting in high crown/implant ratios. However, the maximum ratio allowed, as suggested from conventional prosthodontic literature, might not apply to implantbased prosthodontics. In a prospective study, Rokni and colleagues18 reported the following mean crown/implant ratios: 1.0 for implants of 12 mm in length, 1.4 for 9-mm implants, 1.8 for 7-mm implants, and 2.6 for 5-mm implants. Notwithstanding these rather high crown/implant ratios, the latter authors reported no association between the crown/implant ratios and crestal bone loss. Also, in the retrospective cohort study of Schulte and colleagues,19 a rather high mean crown/ implant ratio was reported, without an association with implant loss. Complications have been reported for vertical augmentation in the mandible.1 If such a procedure is not needed, morbidity, risk, and costs can be reduced. The results of the present study support the use of short implants and might make vertical augmentation procedures redundant in the near future. Before making this procedure to clinical routine, there is a need for longterm follow-up on studies with short implants and high crown/implant ratios. When proven reliable, also from a long-term prospective, short implants may become the treatment of choice for the posterior resorbed mandible as short implants may offer greater simplicity and safety.

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CONCLUSION The 6-mm OsseoSpeed 4.0 S implants with a single restoration placed in the posterior resorbed mandible provide a stable solution with healthy peri-implant soft tissue and high patient satisfaction after 1-year follow-up.

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REFERENCES 1. Esposito M, Grusovin MG, Felice P, et al. The efficacy of horizontal and vertical bone augmentation procedures for dental implants – a Cochrane systematic review. Eur J Oral Implantol 2009; 3:167–184. 2. Renouard F, Nisand D. Short implants in the severely resorbed maxilla: a 2-year retrospective clinical study.

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Clin Implant Dent Relat Res 2005; 7(Suppl 1):S104– S110. Pommer B, Frantal S, Willer J, et al. Impact of dental implant length on early failure rates: a meta-analysis of observational studies. J Clin Periodontol 2011; 9:856–863. Telleman G, Raghoebar GM, Vissink A, et al. A systematic review of the prognosis of short (

Single Restorations in the Resorbed Posterior Mandible Supported by 6-mm Implants: A 1-Year Prospective Case Series Study.

The aim of this prospective case series study was to assess the clinical performance of single restorations in the posterior mandible supported by 6-m...
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