Short-term aesthetic considerations of immediate single-tooth implants

SUMMARY The loss of a single tooth in the esthetic area is for most patients a traumatic event. Nowadays, several treatment modalities are available to replace the failing tooth, such as a resin-bonded restoration or a conventional fixed partial denture. However, since the introduction of implants several decades ago and the increasing body of evidence on the predictability of this alternative, the popularity of the single-tooth implant has increased tremendously. Originally, an initial period of 3 to 6 months of submerged healing was advocated, followed by a second surgical intervention to uncover the implant. Yet, this prolonged treatment time may be considered an important reason to abandon the implantsupported restoration as the treatment of choice by some patients. In light of this argument several clinicians became tempted to insert implants shortly to immediately after extraction and to restore likewise following implant placement (chapter 1). In chapter 2 a review on immediate replacement of a failing tooth in the premaxilla showed that implant survival and even managing the hard tissue levels seem predictable. Survival rates in this limited number of studies were at least comparable to the original protocol and presented promising peri-implant bone loss not surpassing 1 mm. Yet, in the past decade the criteria for success have changed in the interest of an esthetic treatment outcome and as such, the influence of soft tissue changes became of critical importance. Although the papilla levels seemed predictable since these are hardly influenced by the surgical/restorative protocol, maintenance of the midfacial soft tissue levels seemed less predictable. As currently available information on this topic is very scarce, the clinician should be reserved when considering immediate implant placement and provisionalization for replacing single maxillary teeth in the esthetic zone. At the very least, a number of guidelines and prerequisites need to be taken into consideration. The overall aim of this thesis was to elucidate these guidelines and prerequisites, and to evaluate the short-term esthetic outcome of immediate single-tooth implant restorations in the anterior maxilla. Key questions in this respect relate to patient selection, implant selection and treatment protocol (chapter 3). In reference to proper patient selection, the gingival biotype is of particular interest for the clinician, as patients with a thin-scalloped gingival biotype present a higher risk for esthetic complications. Based on this knowledge patients with a thin gingival biotype were systematically excluded from the conducted studies on immediate tooth replacement. The prevalence of the different gingival biotypes was investigated in chapter 4. Out of a large group of young adults 3 clusters with specific features could be identified using simple diagnostic methods. A clear thin gingiva was found in about one third of the sample in mainly female subjects with slender teeth, a narrow zone of keratinized tissue and a highly scalloped gingival margin corresponding to the features of the previously introduced ‘thinscalloped biotype’. A clear thick gingiva was found in about two thirds of the sample in mainly male subjects. About half of them showed quadratic teeth, a broad zone of keratinized tissue and a flat gingival margin corresponding to the features of the previously introduced ‘thick-flat biotype’. The other half could not be classified as such. These subjects Summary 152 showed a clear thick gingiva with slender teeth, a narrow zone of keratinized tissue and a high gingival scallop. Another important issue relates to the implant characteristics, which was included in chapter 5. Recently, implant companies have introduced two-piece implants with micro-textured collars in the interest of hard tissue preservation and/or soft tissue integration. However, these arguments may be premature. At present, it is unclear whether micro-roughened implant necks reduce crestal bone loss. A possible effect may be overruled by the establishment of a biologic width or by other factors influencing crestal bone remodeling. In addition, the orientation and attachment of the collagen fibbers in the peri-implant mucosa are little different as the surface roughness varies at the level of the implant neck. By consequence, micro-roughened implant collars do not provide an obvious advantage. What is more, the long-term impact of these modified collars on the initiation and progression of peri-implant pathology is currently unknown. In conclusion, the clinician should be reserved when using these modified implants. Consequently only screw-type tapered implants with a micro-roughened body and machined collar were adopted in our studies. In our one-year prospective clinical study (chapter 6) all patients underwent the same strategy; that is mucoperiosteal flap elevation, immediate implant placement, insertion of a grafting material between the implant and the socket wall and the connection of a screwretained provisional restoration. The objective of the study was to assess implant survival, hard and soft tissue response and esthetic outcome. Short-term results on implant survival and hard tissue alterations were at least comparable to the outcome of the conventional procedure. Papilla loss and midfacial soft tissue shrinkage were limited to approximally 0.5 mm after one year of observation. Based on these preliminary promising results the proposed treatment protocol was considered a viable solution for well-selected cases. However, as hard and soft tissue alterations are a continuous event further long-term evaluation is required. In chapter 7, the influence of the restorative procedure on the esthetic treatment outcome of the immediate single tooth implant in the anterior maxilla was assessed. Whether the implant was immediately restored or not had no influence on the osseointegration or bone remodeling process. However, it had a significant impact on the soft tissues surrounding the implant. If the implant was not immediately provisionalized, papillae were lost and took up to one year to attain the same height as when the implant was immediately restored. Even more important for esthetics was the additional loss of midfacial soft tissue by 0.75 mm on average, which showed a permanent character during the study period. By consequence, if the condition of the selected case permits it, immediate provisionalization should be advised to minimize midfacial soft tissue shrinkage. Chapter 8 is attributed to the suprastucture, and gives a detailed description of four restorative key elements essential to obtain an optimal esthetic outcome. A first one is to instantly provisionalize the immediate single-tooth implant in light of optimal soft tissue preservation. Second, the provisional restoration should meet a number of morphological prerequisites. A third restorative factor includes the accurate replication of the soft tissue architecture for the permanent restoration in order to avoid subsequent soft tissue changes. Summary 153 And finally a fourth factor decisive for success relates to the choice of the abutment material. This thesis showed that the immediate replacement of a failing tooth with an implant and screw-retained restoration is a viable treatment concept. It is an appealing strategy for as well the patient as the clinician. However, careful patient selection, treatment planning and experienced clinicians seem of critical importance to obtain optimal esthetics. Future research should consider long-term prospective and controlled clinical studies in order to document the overall outcome of this treatment strategy

Immediate single-tooth implants in the anterior maxilla: a 1-year case cohort study on hard and soft tissue response

Aim: The objective of the present study was to assess implant survival rate, hard and soft tissue response and aesthetic outcome 1 year after immediate placement and provisionalization of single-tooth implants in the pre-maxilla. All patients underwent the same strategy, that is mucoperiosteal flap elevation, immediate implant placement, insertion of a grafting material between the implant and the socket wall and the connection of a screw-retained provisional restoration. Material and Methods: Thirty consecutive patients were treated for single-tooth replacement in the aesthetic zone by means of immediate implant placement and provisionalization. Reasons for tooth loss included caries, periodontitis or trauma. At 6 months, provisional crowns were replaced by the permanent ones. Clinical and radiographic evaluation was completed at 1, 3, 6 and 12 months to assess implant survival and complications, hard and soft tissue parameters and patient's aesthetic satisfaction. Results: One implant had failed at 1 month of follow-up, resulting in an implant survival rate of 97%. Radiographic examination yielded 0.98 mm mesial, respectively, 0.78 mm distal bone loss. Midfacial soft tissue recession and mesial/distal papilla shrinkage were 0.53, 0.41and 0.31 mm, respectively. Patient's aesthetic satisfaction was 93%. Conclusions: The preliminary results suggest that the proposed strategy can be considered to be a valuable treatment option in well-selected patients

Single-tooth replacement in the anterior maxilla by means of immediate implantation and provisionalization : a review

Objectives: The objective of this study was to assess to what extent the outcome of immediate implantation and provisionalization for replacing single maxillary teeth in the esthetic zone is favorable and predictable from biologic and esthetic points of view. Material and Methods: An electronic search (MEDLINE and Cochrane Oral Health Group Specialized Trials Register) and a manual search were performed to detect studies concerning maxillary single-tooth replacements by means of dental implants immediately placed into fresh extraction sockets and provisionalized within the first 24 hours. Only full-text reports on clinical studies published in English up to June 2006 were included. Case reports and reviews on the topic of interest were excluded. Results: Eleven studies were selected. Based on a qualitative data analysis, implant survival and even management of papilla levels seem predictable following immediate implantation and provisionalization. However, maintaining the midfacial gingival margin may be more problematic, since postextraction bone remodeling and therefore marginal gingival changes will occur irrespective of the timing of the placement of an implant. The long-term impact of this remodeling is currently unclear and needs to be elucidated in future research. Conclusion: The clinician is recommended to be reserved when considering immediate implant placement and provisionalization for replacing single maxillary teeth in the anterior zone. At the very least, a number of guidelines and prerequisites need to be taken into consideration

Numerical modelling of control strategies and accumulator effect of a hydraulic power take-off system

Wave energy is a promising new player in the renewable energy field. The exploitable power within the world's oceans is significant and many developers try to capture it by developing wave energy converter (WEC) concepts. This research focussed on the conversion of the WEC motions into usable electricity by the power take-off system (PTO). Specifically, a hydraulic PTO system with an accumulator as energy buffer was studied. The power absorption was calculated, with implementation of several control strategies to maximize the output. Here, a distinction was made between fast strategies, which alter the control on a wave-by-wave basis, and slow strategies, which apply constant control over longer time windows. Additionally, the effect of the accumulator volume on the power conversion and the system pressure was studied. Results indicated that control strategies positively influence the PTO performance and that the accumulator volume is of major importance in hydraulic PTOs

The gingival biotype assessed by experienced and inexperienced clinicians

AIM: A recent cluster analysis has identified three gingival biotypes among 100 periodontally healthy subjects based on different combinations of morphometric data related to maxillary front teeth and surrounding soft tissues. Patients with a thin-scalloped biotype are considered at risk because they have been associated with a compromised soft tissue response following surgical and/or restorative therapy. Hence, an accurate identification of these high-risk patients is warranted. The purpose of the present study was to evaluate the precision of simple visual inspection as a method to identify the gingival biotype by experienced and inexperienced clinicians. MATERIAL AND METHODS: Fifteen clinicians (five Restorative Dentists, five Periodontists and five Students) were invited to assess the gingival biotype (thin-scalloped, thick-flat, thick-scalloped) of 100 periodontally healthy subjects based on clinical slides. Cluster analysis on these subjects was used as the gold standard and the accuracy in identifying the gingival biotype was determined using percentile agreement and kappa statistics. Intra- and inter-examiner reliability were also calculated. RESULTS: The gingival biotype was accurately identified only in about half of the cases irrespective of the clinician's experience. The thick-flat biotype was mostly recognized especially by experienced clinicians (> or =70% of the cases). Nearly half of the thin-scalloped cases were misclassified. The intra-examiner repeatability was fair to substantial (kappa: 0.328-0.670) and the inter-examiner reproducibility was slight to moderate (kappa: 0.127-0.547). CONCLUSIONS: Simple visual inspection may not be considered a valuable method to identify the gingival biotype as nearly half of the high-risk patients are overlooked

Single implant treatment in healing versus healed sites of the anterior maxilla: a clinical and radiographic evaluation

Purpose: The aim was to document the Nobelreplace tapered TiUnite® (Nobel Biocare, Göteborg, Sweden) implant system used by experienced clinicians in daily practice for replacing single maxillary anterior teeth and to compare the clinical and radiographical outcome between implants installed in healing sites (early implant placement) and fully-healed sites (conventional implant placement) after on average two and a half years of function. Material and methods: A cross-sectional study in patients who had been treated by two periodontists and two prosthodontists in 2006 and 2007 was conducted. Surgical treatment involved standard flap elevation without releasing incisions and restorative procedures included cemented crowns in all patients. Only straightforward single implant treatments in healing sites (6 – 8 weeks following tooth extraction) and fully-healed sites (≥ 6 months following tooth extraction) were considered with both neighbouring teeth present and without the need for hard and/or soft tissue grafting. Clinical and radiographical analyses of all implants were performed by a blinded clinician who had not been involved in the treatment. Results: 49/53 eligible single implants (22 early and 27 conventionally placed implants) in 44/48 patients were available for scrutiny. There was no statistically significant difference in implant survival between early (95 %) and conventionally (93 %) installed implants (p = 1.000). Mean bone level to the implant-abutment interface was 1.25 mm and 1.02 mm for early, respectively conventional implant placement (p = 0.220). In spite of fairly low plaque levels (26 %), overall peri-implant bleeding was quite prevalent (36 %). Mean peri-implant probing depth was 3.3 mm. 5 restorations had experienced technical complications. Conclusions: Single Nobelreplace tapered TiUnite® implants installed in healing as well as in healed sites of the anterior maxilla are predictable. Both strategies seem equally successful in terms of implant survival, bone remodelling, clinical response and risk for complications

Clinical benefits of subgingival chlorhexidine varnish application as an adjunct to same-day full-mouth root planing: a pilot study

Background: Although scaling and root planing are considered the therapeutic standard for periodontitis, weakly responding sites often occur. To improve treatment outcome, several chemomechanical treatment concepts have been developed. Recently, the clinical surplus value of a highly concentrated chlorhexidine varnish has been shown when used as an adjunct to sequential scaling and root planing. The aim of this study was to explore the clinical effects of a treatment strategy for chronic periodontitis based on a combination of same-day full-mouth root planing and subgingival chlorhexidine varnish administration. Methods: A randomized, controlled, single-blind, parallel trial was conducted on 12 chronic periodontitis patients. The control group received oral hygiene instructions and same-day full-mouth root planing. The test group received the same instructions and treatment; however, all pockets were additionally disinfected using a chlorhexidine varnish. Clinical response parameters were recorded at baseline and subsequently after 1 and 3 months. Results: Both treatment strategies showed significant reductions in probing depth at both follow-up visits in comparison with baseline levels (P = 7 mm) was found favoring the test group. Conclusion: These preliminary findings suggest that the outcome of same-day full-mouth root planing may benefit from the subgingival administration of a highly concentrated chlorhexidine varnish

A chlorhexidine varnish implemented treatment strategy for chronic periodontitis: short-term clinical observations

Objectives: The aim of this study was to investigate the clinical outcome of a subgingivally applied chlorhexidine varnish when used as an adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis. Materials and Methods: A randomized controlled, single blind, parallel trial was conducted on the basis of 16 volunteers suffering from chronic periodontitis. The control group received oral hygiene instructions and was scaled and root planed in two sessions. The test group received the same instructions and treatment, however, all pockets were additionally disinfected using a chlorhexidine varnish. The gingival index, plaque index, bleeding on probing, probing pocket depth (PPD) and clinical attachment level (CAL) were recorded at baseline and subsequently after 1 and 3 months. Results: Both treatment strategies showed significant reductions in PPD and CAL at both follow-up visits by comparison with baseline levels (p < 0.001). Yet, at study termination, combination therapy resulted in additional pocket reductions between 0.73 and 1.23 mm (p < 0.02), and clinical attachment gains between 0.63 and 1.09 mm (p < 0.02). Conclusions: These findings suggest that a varnish-implemented strategy may improve the clinical outcome for the treatment of chronic periodontitis in comparison with SRP alone

Subgingival chlorhexidine varnish administration as an adjunct to same-day full-mouth root planing, I: clinical observations

Background: Chemo-mechanical treatment concepts have been developed to improve the outcome of non-surgical periodontal therapy. Recently, the clinical additive value of a supersaturated chlorhexidine varnish was shown when used as an adjunct to staged scaling and root planing. The aim of this study was to investigate the clinical effects of a treatment strategy for chronic periodontitis based on a combination of same-day full-mouth root planing and subgingival chlorhexidine varnish administration. Methods: A randomized, controlled, single-blind, parallel trial was conducted on 33 non-smoking chronic periodontitis patients. The control group received oral hygiene instructions and same-day full-mouth root planing. The test group received the same instructions and treatment; however, all pockets were disinfected using a chlorhexidine varnish. Clinical response parameters were recorded at baseline and after 1, 3, and 6 months. Results: Both groups showed significant reductions in probing depth following therapy (P = 7 mm) was found at study termination. Additive clinical attachment gains seemed to be temporary. Impermanent extra pocket reductions and clinical attachment gains were found for initially medium-deep pockets (4 to 6 mm). Conclusion: The outcome of same-day full-mouth root planing may benefit from the subgingival administration of a highly concentrated chlorhexidine varnish, at least in terms of pocket reduction in initially deep sites ( >= 7 mm)