Ausgabe 3/2013,   Jahrgang 33   (04.04.2013)

Seite 259
Editorial: Do Zirconia Ceramics Have a Future in Restorative Dentistry?
Strub, Joerg R.

Seite 261 - 267
Maintaining Interimplant Crestal Bone Height Via a Combined Platform- Switched, Laser-Lok Implant/Abutment System: A Proof-of-Principle Canine Study
Nevins, Myron / Nevins, Marc / Gobbato, Luca / Lee, Hyo-Jung / Wang, Chin-Wei / Kim, David M.

Interimplant papillae are critical for achieving esthetic implant-supported restorations in the maxillary esthetic zone. Stable papillary anatomy, however, depends upon a stable volume of underlying crestal bone for support. Multiple studies have documented a critical interimplant distance of 3 mm under which crestal bone resorption occurs. This preclinical proofof- principle canine study examines a novel implant-abutment system design, combining platform switching with precisely configured laserablated abutment and implant microgrooves to maintain interimplant crestal bone at interimplant distances of 2 and 4 mm. Results of this initial preclinical study suggest that it is possible through precise implant/ abutment design modifications to place adjacent implants at distances of 2 to 4 mm without inducing subpapillary crestal bone loss.

Seite 269 - 279
A Histomorphometric Comparison of Bio-Oss Alone Versus Bio-Oss and Platelet-Derived Growth Factor for Sinus Augmentation: A Postsurgical Assessment
Froum, Stuart J. / Wallace, Stephen / Cho, Sang-Choon / Rosenberg, Edwin / Froum, Scott / Schoor, Robert / Mascarenhas, Patrick / Tarnow, Dennis P. / Corby, Patricia / Elian, Nicolas / Fickl, Stefan / Ricci, John / Hu, Bin / Bromage, Timothy / Khouly, Ism

The purpose of this study was to assess vital bone formation at 4 to 5 months and 7 to 9 months following sinus augmentation with anorganic bovine bone matrix (ABBM) with and without recombinant human platelet-derived growth factor (rhPDGF). Twenty-four subjects received bilateral sinus elevation surgery with ABBM on one side and ABBM and rhPDGF on the contralateral side. Twelve patients had core sampling at 4 to 5 months and 12 patients at 7 to 9 months postoperatively. In subjects with cores taken at 4 to 5 months, mean vital bone, connective tissue, and residual graft were 11.8%, 54.1%, and 33.6%, respectively, with ABBM alone. Cores of sinuses filled with ABBM and rhPDGF showed mean 21.1% vital bone, 51.4% connective tissue, and 24.8% residual graft. Paired t test showed a statistically significant difference in vital bone. In cores taken at 7 to 9 months, the values for ABBM alone and ABBM + rhPDGF were 21.4% vs 19.5% vital bone, 28.4% vs 44.2% connective tissue, and 40.3% residual graft vs 35.5%. There was no statistically significant difference in vital bone at 7 to 9 months after surgery. Test and control groups showed clinically acceptable levels of vital bone both at 4 to 5 months and 7 to 9 months postsurgery. However, vital bone formation was significantly greater in the 4- to 5-month sections of ABBM + rhPDGF vs the Bio-Oss alone. In the 7- to 9-month specimens, this difference disappeared. More rapid formation of vital bone with the addition of rhPDGF may allow for earlier implant placement.

Seite 281 - 287
Tissue-Engineered Cultured Periosteum Sheet Application to Treat Infrabony Defects: Case Series and 5-Year Results
Okuda, Kazuhiro / Kawase, Tomoyuki / Nagata, Masaki / Yamamiya, Kanoko / Nakata, Koh / Wolff, Larry F. / Yoshie, Hiromasa

One-year data after autologous grafting of infrabony periodontal defects with human cultured periosteum sheets in combination with platelet-rich plasma and hydroxyapatite granules have shown favorable clinical and radiographic results. A 5-year follow-up evaluation of 22 selected patients indicated that treated infrabony defects remained stable. Radiographically, there was an increase in osseous radiopacity and bone trabeculation suggesting further bone maturation. This novel tissue-engineered periodontal treatment approach has resulted in significant clinical improvement, and defects remained stable after 5 years.

Seite 289 - 296
A Classification System for Crestal and Radicular Dentoalveolar Bone Phenotypes
Mandelaris, George A. / Vence, Brian S. / Rosenfeld, Alan L. / Forbes, David P.

Pretreatment knowledge of crestal and radicular dentoalveolar zones and their associated thicknesses can improve risk assessment to meet esthetic and functional goals, particularly when discrepancies in anterior maxillary and mandibular arches exist and when an anterior protected articulation is to be achieved. This paper discusses a new classification of dentoalveolar bone phenotypes that differentiates the alveolar crestal zone from that of the radicular zone and classifies the thickness of facial bone at each compartment to aid in interdisciplinary dentofacial therapy risk assessment. The zone of crestal bone is defined as the region of the tooth alveolus measured from the cementoenamel junction (CEJ) to a point 4 mm apical. The dentoalveolar radicular zone is dependent upon the individual root length. It begins at a point 4 mm apical to the CEJ (base of the crestal zone) and extends the length of the tooth root. Dentoalveolar bone phenotype at both zones (crestal and remaining radicular alveolar aspect) can be categorized as either thick or thin. Thick is defined as >= 1 mm of facial bone width while thin is < 1 mm.

Seite 299 - 307
Horizontal Ridge Augmentation with a Collagen Membrane and a Combination of Particulated Autogenous Bone and Anorganic Bovine Bone-Derived Mineral: A Prospective Case Series in 25 Patients
Urban, Istvan A. / Nagursky, Heiner / Lozada, Jaime L. / Nagy, Katalin

This prospective case series evaluated the use of a resorbable natural collagen membrane with a mixture of autogenous bone and anorganic bovine bone- derived mineral (ABBM) for lateral ridge augmentation and subsequent implant placement. A mixture (1:1) of particulated autogenous bone and ABBM was used for lateral ridge augmentation and covered with a resorbable, natural collagen bilayer membrane to treat knife-edge ridges and prepare them for implant placement. Ridge measurements were obtained pre- and postsurgery, complications recorded, and biopsy specimens examined histologically. Seventysix implants were placed in 25 patients with 31 knife-edge ridge surgical sites. One defect had a bone graft complication (3.2%; exact 95% confidence interval: 0.1%, 16.7%). Clinical measurements revealed an average of 5.68 mm (standard deviation [SD] = 1.42 mm) of lateral ridge augmentation after a mean 8.9-month (SD = 2.1 months) graft healing period. Clinically, all treated ridges were sufficient in width for subsequent implant placement. All implants survived with an average follow-up of 20.88 months (SD = 9.49 months). Histologic analysis of nine surgical sites showed that ABBM was connected with a dense network of newly formed bone with varying degrees of maturation. Histomorphometric analysis demonstrated that autogenous bone represented a mean of 31.0% of the specimens, ABBM 25.8%, and marrow space 43.2%. The treatment of horizontally deficient alveolar ridges with the guided bone regeneration technique using autogenous bone mixed with ABBM and a natural collagen resorbable barrier membrane can be regarded as successful. Implant success and survival need to be confirmed with long-term follow-up examinations.

Seite 309 - 315
Treatment of Excessive Gingival Display Using a Modified Lip Repositioning Technique
Ribeiro-Júnior, Noé Vital / Campos, Thiago Veiga de Souza / Rodrigues, Jefferson Guilherme / Martins, Thiago Modolo Azevedo / Silva, Cléverson O.

Excessive gingival display during smiling ("gummy smile") is an esthetic issue that affects a considerable part of the population. The hyperactivity of the elevator muscle of the upper lip is one of the main causes of a gummy smile, and several techniques have been proposed for its treatment. The aim of this report is to describe a modification of the lip repositioning technique to achieve stable and significant outcomes through a more conservative procedure. Two patients complaining about a gummy smile were treated with the proposed technique and presented, after a 6-month follow-up, significant improvement in the amount of gingival exposure and esthetic satisfaction.

Seite 317 - 325
Accuracy of a Computer-Aided Implant Surgical Technique
Cassetta, Michele / Stefanelli, Luigi V. / Giansanti, Matteo / Di Mambro, Alfonso / Calasso, Sabrina

The purpose of this in vivo retrospective study was to evaluate the accuracy of a computer-designed stereolithographic surgical guide. One hundred eleven implants were placed in 10 patients. Pre- and postoperative computed tomography images were compared using specific software. Global, angular, depth, and lateral deviations were calculated between planned and placed implants. Mean global deviations between planned and placed implants at the coronal and apical aspects were 1.52 mm (range, 0.13 to 3.00 mm) and 1.97 mm (range, 0.34 to 4.23 mm), respectively, while the mean angular deviation was 4.68 degrees (range, 0.10 to 15.25 degrees). This study highlighted a reasonable mean accuracy with relatively high maximum deviations between the postoperative position and the preoperative plan. These results should serve as a warning for the clinician if implants are placed near vital structures.

Seite 327 - 335
Esthetic Treatment of Peri-implant Soft Tissue Defects: A Case Report of a Modified Surgical-Prosthetic Approach
Zucchelli, Giovanni / Mazzotti, Claudio / Mounssif, Ilham / Stefanini, Martina

A major esthetic concern is soft tissue defects around implant restorations, which often result in an extra long prosthetic crown. This report describes a modified prosthetic-surgical approach to the treatment of peri-implant horizontal and vertical soft tissue defects in an esthetically demanding patient. One month before surgery, the implant crown restoration was removed, the preexisting implant abutment was reduced, and a short provisional crown, at the level of the homologous contralateral incisor, was applied. A bilaminar technique, consisting of an envelope coronally advanced flap covering two connective tissue grafts, was used to treat the soft tissue defects around the implant site. Four months after surgery, a new implant abutment and provisional crown were applied for soft tissue conditioning before the final impression. Nine months after surgery, the peri-implant soft tissue margin was 4 mm more coronal compared with baseline and at the same soft tissue margin level of the right central incisor. A 2.2-mm increase in buccal soft tissue thickness measured 1.5 mm apical to the soft tissue margin was accomplished. The emergence profile of the replaced tooth faithfully reproduced that of the healthy homologous contralateral central incisor. Two years after surgery, the soft tissue margin was stable and the esthetic appearance of the implant site was well maintained. This report demonstrates the possibility of fully correcting severe vertical and horizontal peri-implant soft tissue defects and achieving high patient satisfaction through a combined mucogingival and prosthetic treatment.

Seite 337 - 345
Anatomical Characteristics and Dimensions of Edentulous Sites in the Posterior Maxillae of Patients Referred for Implant Therapy
Nunes, Leandro Soeiro de Souza / Bornstein, Michael M. / Sendi, Pedram / Buser, Daniel

The purpose of this study was to analyze the width and height of edentulous sites in the posterior maxilla using cone beam computed tomography (CBCT) images from patients referred for implant therapy. A total of 122 CBCT scans were included in the analysis, resulting in a sample size of 252 edentulous sites. The orofacial crest width was measured in coronal slices, perpendicular to the alveolar ridge. The bone height was analyzed in the respective sagittal slices. Additionally, the following secondary outcome parameters were evaluated: the morphology of the sinus floor, the presence of septa in the maxillary sinus, and the thickness of the sinus membrane. The mean crest width for all analyzed sites was 8.28 mm, and the mean bone height was 7.22 mm. The percentage of patients with a crest width of less than 6 mm was 27% in premolar sites and 7.8% in molar sites. The bone height decreased from premolar to molar areas, with a high percentage of first and second molar sites exhibiting a bone height of less than 5 mm (54.12% and 44.64%, respectively). Regarding the morphology of the sinus floor, 53% of the edentulous sites exhibited a flat configuration. A septum was present in 67 edentulous sites (26.59%). Analysis of the sinus membrane revealed 88 sites (34.9%) with increased mucosal thickness (> 2 mm). For the crest width, the location of the edentulous site and the morphology of the sinus floor were both statistically significant variables. For the crest width and mean bone height, the location of the edentulous site and the morphology of the sinus floor were both statistically significant variables. The study confirmed that a high percentage of edentulous sites in the posterior maxilla do require sinus floor elevation to allow the placement of dental implants. Therefore, a detailed three-dimensional radiograph using CBCT is indicated in most patients for proper treatment planning.

Seite 347 - 353
Assessment of Maxillary Central Incisor Crown Form
Senn, Luis F. / Lazos, Jerónimo Pablo / Brunotto, Mabel

Incisor crown form is thought to be associated with different periodontal features, and it is hypothesized that there are measures of the maxillary central incisor that can be used to characterize its form. The aim of this study was to assess maxillary central incisor crown dimensions to determine morphologic groups. One-hundred fifty sound maxillary central incisors without excessive evidence of incisal wear were utilized. On each crown, several reference points were marked and mesiodistal and axial diameters were measured using a digital caliper. A ratio between the minor and major mesiodistal diameters was determined to assess dental forms. Maxillary central incisor form was categorized into three groups based on the upper limits of three intervals as cutoff points. The measurements were performed in a double blind fashion. The reliability of measurements was estimated by the Pearson correlation coefficient for each tooth, setting a value > 0.8. The percentage of maxillary central incisors in each group was 56.67% for group 1 (stout), 22.67% for group 2 (intermediate), and 20.66% for group 3 (strangled). The results suggest that maxillary central incisor morphology can be properly assessed through quantifiable methods. The minor/major mesiodistal ratio is simple, quantitative, and easily reproduced. It is a quantifiable definition of dental forms based on characteristics that are not modified by the position of the gingival margin or incisal wear. Hence, the grade of cervical convergence could help clinicians assess tooth shape before performing restorative, orthodontic, or surgical treatments.

Seite 355 - 363
Magnesium-Substituted Hydroxyapatite Grafting Using the Vertical Inlay Technique
Felice, Pietro / Lizio, Giuseppe / Marchetti, Claudio / Checchi, Luigi / Scarano, Antonio

The reconstruction of a severely atrophic left posterior mandible using inlay magnesium-substituted hydroxyapatite grafting is described. Three months after reconstruction, a bone specimen was retrieved, and two dental implants were placed. A mean vertical bone gain of 4.9 mm was measured at the time of implant placement, and no problems were recorded at delivery of the provisional and definitive prostheses 4 and 8 months after implant placement, respectively. Histologic analysis revealed residual grafted material infiltrated by newly formed bone. In this clinical case, Mg-hydroxyapatite was demonstrated to be an effective grafting material for reconstruction of the posterior mandible using the inlay technique.

Seite 365 - 372
Bone Level Changes in Dental Implants with Platform-Switched Design After Immediate and Delayed Placement in the Maxilla
Heinemann, Friedhelm / Biffar, Reiner / Schwahn, Christian / Mundt, Torsten

This study sought to evaluate platform-switched implants for immediate placement. A total of 136 implants were placed in 58 patients using either an immediate or delayed implant protocol. Bone level changes of the implants were measured mesially and distally and statistically analyzed with linear mixed models. No implant was lost. There was no significant difference between immediate and delayed implants in approximal bone level changes during the first year (95% confidence interval: -0.10 to -0.01 for immediate versus -0.14 to -0.07 for delayed implants). Subsequent bone resorption was negligible in both groups.

Seite 373 - 377
Dentin Bond Strength: Influence of Er:YAG and Nd:YAG Lasers
Ribeiro, Carolina Ferraz / Gonçalves, Sérgio Eduardo de Paiva / Yui, Karen Cristina Kazue / Borges, Alessandra Bühler / Barcellos, Daphne Câmara / Brayner, Ricardo

The aim of this study was to investigate the effects of Er:YAG and Nd:YAG lasers on the shear bond strength of composite resin to dentin. The coronal portion of 56 human molars was divided into three parts, and the dentin thickness was standardized at 2 mm. A 3-mm hole was marked in the center of each tooth with sealing tape paper. The specimens (n = 14) were then divided into four groups: (1) acid etching + Single Bond (SB) (control), (2) acid etching + SB + Nd:YAG laser irradiation (before adhesive curing), (3) thermal etching with the Er:YAG laser + SB, and (4) thermal etching with the Er:YAG laser + SB + Nd:YAG laser irradiation (before adhesive curing). A composite resin cylinder was built into the delimited area for conducting the shear bond strength test on the universal testing machine. The means ± standard deviations were: group 1, 17.05 ± 4.15 MPa; group 2, 16.90 ± 3.36 MPa; group 3, 12.12 ± 3.85 MPa; and group 4, 12.92 ± 2.73 MPa. Groups 1 and 2 presented significantly higher values than groups 3 and 4. It was concluded that conventional etching with 37% phosphoric acid yielded significantly higher bond strength values compared to thermal etching with the Er:YAG laser. The Nd:YAG laser did not significantly influence the bond strength.

Online Article, Seite 398
Online Article: The Soft Tissue Wall Technique for the Regenerative Treatment of Non-contained Infrabony Defects: A Case Series
Rasperini, Giulio / Acunzo, Raffaele / Barnett, Andrew / Pagni, Giorgio

The ability to stabilize the blood clot is crucial in achieving predictable periodontal regeneration in infrabony defects. Unfortunately, micromovements may cause degradation of the clot-root interface and result in suboptimal wound healing. Current surgical and suturing techniques are aimed at reducing flap micromovement because flap management is one of the main factors influencing the stability of the clot. The aim of this paper is to describe the use of the soft tissue wall technique to enhance periodontal tissue regeneration outcomes of challenging non-contained infrabony defects. Nine one-wall infrabony defects were treated with a combination of a papilla preservation technique and a coronally advanced flap. Enamel matrix derivative was delivered to the defect, but no bone grafting materials or membranes were employed. Mean 1-year probing depth reduction was 6.3 ± 2.0 mm (P < .001) and mean clinical attachment gain was 7.1 ± 1.0 mm (P < .001). All treated sites showed a mean reduction of exposed root surface equal to 1.0 ± 0.4 mm (P = .05). The results suggest the possibility of improving the regenerative potential of a one-wall infrabony defect by the creation of a stable soft tissue wall while also enhancing the esthetic outcome of the surgical procedure. Further studies with a larger number of patients are needed to support these preliminary data.

Online Article, Seite 399
Online Article: Comparative Evaluation of the Effectiveness of Coronally Positioned Flap With or Without Acellular Dermal Matrix Allograft in the Treatment of Multiple Marginal Gingival Recession Defects
Thombre, Vivek / Koudale, Somnath B. / Bhongade, Manohar L.

Gingival recession remains an important problem in dental esthetics. Various surgical techniques have been proposed for treating multiple gingival recessions. The objective of this study was to evaluate and compare the effectiveness of a coronally positioned flap (CPF) with or without acellular dermal matrix allograft (ADMA) in the treatment of multiple marginal tissue recession. Twenty patients with a mean age of 31.6 years presented with 43 buccal/labial multiple recession defects (Miller Class I/II). Ten patients each were randomly assigned to one of two treatment groups: group 1 (ADMA) or group 2 (CPF). The clinical parameters gingival recession (GR), probing pocket depth (PD), clinical attachment level (CAL), and width of the keratinized gingiva (KG) were recorded before surgery and 6 month postsurgery. The mean baseline recession defect was 3.0 mm for group 1 and 2.8 mm for group 2. After 6 months, both treatments resulted in significant root coverage (P < .01), reaching an average of 2.7 mm (90%) in group 1 and 1.8 mm (66%) in group 2. The difference in recession reduction between treatments was statistically significant. There were no statistically significant differences between the treatments in PD and KG. CAL gain (3.0 mm) was significantly higher in group 1 compared with group 2 (2.0 mm). The results of this study demonstrate that ADMA with a CPF is an effective procedure for the treatment of multiple gingival recessions.