Critical horizontal dimensions of interproximal and buccal bone around implants for optimal aesthetic outcomes: a systematic review

Reliability and Failure Mode of Ti-Base Abutments Supported by Narrow/Wide Implant Systems

To assess the reliability and failure modes of Ti-base abutments supported by narrow and wide-diameter implant systems. Narrow (Ø3.5 × 10 mm) and wide (Ø5 × 10 mm) implant systems of two different manufacturers with internal conical connections (16°) and their respective Ti-base abutments (3.5 and 4.5 mm) were evaluated. Ti-base abutments were torqued to the implants, standardized metallic maxillary incisor crowns were cemented, and step stress accelerated life testing of eighteen assemblies per group was performed in three loading profiles: mild, moderate, and aggressive until fracture or suspension. Reliability for missions of 100,000 cycles at 100 and 150 N was calculated, and fractographic analysis was performed. For missions at 100 N for 100,000 cycles, both narrow and wide implant systems exhibited a high probability of survival (≥99%, CI: 94-100%) without significant differences. At 150 N, wide-diameter implants presented higher reliability (≥99%, CI: 99-100%) compared to narrow implants (86%, CI: 61-95%), with no significant differences among manufacturers. Failure mode predominantly involved Ti-base abutment fractures at the abutment platform. Ti-base abutments supported by narrow and wide implant systems presented high reliability for physiologic masticatory forces, whereas for high load-bearing applications, wide-diameter implants presented increased reliability. Failures were confined to abutment fractures.

Influence of buccal and palatal bone thickness on post-surgical marginal bone changes around implants placed in posterior maxilla: a multi-centre prospective study

BACKGROUND

Numerous clinical variables may influence early marginal bone loss (EMBL), including surgical, prosthetic and host-related factors. Among them, bone crest width plays a crucial role: an adequate peri-implant bone envelope has a protective effect against the influence of the aforementioned factors on marginal bone stability. The aim of the present study was to investigate the influence of buccal and palatal bone thickness at the time of implant placement on EMBL during the submerged healing period.

METHODS

Patients presenting a single edentulism in the upper premolar area and requiring implant-supported rehabilitation were enrolled following inclusion and exclusion criteria. Internal connection implants (Twinfit, Dentaurum, Ispringen, Germany) were inserted after piezoelectric implant site preparation. Mid-facial and mid-palatal thickness and height of the peri-implant bone were measured immediately after implant placement (T0) with a periodontal probe and recorded to the nearest 0.5 mm. After 3 months of submerged healing (T1), implants were uncovered and measurements were repeated with the same protocol. Kruskal-Wallis test for independent samples was used to compare bone changes from T0 to T1. Multivariate linear regression models were built to assess the influence of different variables on buccal and palatal EMBL.

RESULTS

Ninety patients (50 females, 40 males, mean age 42.9 ± 15.1 years), treated with the insertion of 90 implants in maxillary premolar area, were included in the final analysis. Mean buccal and palatal bone thickness at T0 were 2.42 ± 0.64 mm and 1.31 ± 0.38 mm, respectively. Mean buccal and palatal bone thickness at T1 were 1.92 ± 0.71 mm and 0.87 ± 0.49 mm, respectively. Changes in both buccal and palatal thickness from T0 to T1 resulted statistically significant (p = 0.000). Changes in vertical bone levels from T0 to T1 resulted not significant both on buccal (mean vertical resorption 0.04 ± 0.14 mm; p = 0.479) and palatal side (mean vertical resorption 0.03 ± 0.11 mm; p = 0.737). Multivariate linear regression analysis showed a significant negative correlation between vertical bone resorption and bone thickness at T0 on both buccal and palatal side.

CONCLUSION

The present findings suggest that a bone envelope > 2 mm on the buccal side and > 1 mm on the palatal side may effectively prevent peri-implant vertical bone resorption following surgical trauma.

TRIAL REGISTRATION

The present study was retrospectively recorded in a public register of clinical trials ( www.

CLINICALTRIALS

gov - NCT05632172) on 30/11/2022.

Morphological Assessment of Nasopalatine Canal Using Cone Beam Computed Tomography: A Retrospective Study of 124 Consecutive Patients

This study aimed to assess and analyze the morphology and dimensions of the nasopalatine canal (NPC), as well as the adjacent buccal osseous plate (BOP), and to investigate the effect of gender, edentulism, NPC types, absence of maxillary central incisors (ACI) and age on the NPC and BOP, using cone beam computed tomography (CBCT). A total of 124 CBCT examinations (67 female and 57 male patients) were retrospectively included and evaluated. The assessment of the dimensions of the NPC, as well as the dimensions of the adjacent BOP, was performed by three Oral and Maxillofacial Radiologists on reconstructed sagittal and coronal CBCT sections under standardized conditions. Regarding the dimensions of the NPC and the adjacent BOP, the mean values were significantly higher among males than females. Furthermore, edentulous patients showed a significant reduction in BOP dimensions. Additionally, NPC types showed a significant effect on the length of the NPC, and the ACI had a significant effect on reducing BOP dimensions. Age had a significant effect on the diameter of the incisive foramen, with the mean values generally increasing with an increasing age. CBCT imaging of this anatomical structure contributes significantly to its full assessment.

Biomechanical factors in the open gingival embrasure region during the intrusion of mandibular incisors: A new model through finite element analysis

Introduction: Open gingival embrasure (OGE) is a common complication in adults following clear aligner therapy and the influence of gingival or alveolar bone biotype on OGE is of great concern. Unfortunately, due to the limited number of patients with clearaligner therapy and the clinical methods to distinguish the gingival biotype of patients being invasive, it is difficult to carry out clinical studies on the gingival or alveolar bone biotype of the OGE. In the meanwhile, the detailed biomechanics of the occurrence of OGE remains unknown. The goal of this study was to establish a new model to simulate the virtual space region, namely, the OGE region, to investigate the relationship between alveolar bone biotype and the occurrence of OGE, and explore potential biomechanical factors related to OGE.

Methods: The OGE region in the interproximal space was established using a filler with a very low modulus of elasticity (1 × 10−6 MPa). To illustrate the biomechanics of OGE more exhaustively, a line was created at the top of the alveolar crest along the proximal tooth root. FEA was then used to analyze the biomechanics of the surrounding tissues, the OGE region and the line at the top of the alveolar crest along the proximal tooth root of the central incisor under two different labial bone thicknesses (thick and thin) with an axial inclination of 80°, 90° and 100°.

Results: During intrusion of the incisors in clear aligner therapy, as inclination increased or bone tissue became thinner, the stress in the surrounding tissues [tooth root, alveolar crest, and periodontal ligament (PDL)] was greater. In the OGE region and interproximal alveolar crest, the strain increased with increasing inclination and labial bone thinning. The results from the line at the top of the alveolar crest along the proximal tooth root showed more detailed biomechanics: In all groups, stress and strain were focused on the mesial-labial alveolar crest. Interestingly, our results also demonstrated that when OGE occurs, other complications may arise, including root resorption and bone dehiscence.

Single-rooted extraction socket classification: A systematic review and proposal of a new classification system based on morphologic and patient-related factors

Taxonomy and classification of a disease contributes to facilitating the diagnosis and treatment planning process and simplifies communication between clinicians. The aim of this study was to provide a critical appraisal based on a systematic review of the single-rooted extraction socket (ES) classifications and subsequently, introduce a new classification system combining the cornerstones of the previously proposed systems and based on the latest consensus in implant dentistry. Following the systematic search process in PubMed, EMBASE, and SCOPUS databases 13 ES classifications were detected. The most repeated hard and soft tissue factors in the previous classifications were buccal bone dehiscence, interproximal bone, gingival recession, and soft tissue phenotype. However, there was minimal attention to patient-related factors such as systemic conditions and smoking. Therefore, a new classification system based on the combination of patient-related factors, clinical and radiographical parameters was proposed. This divides an ES into three types. Class I and II sockets are candidates for receiving immediate implant placement and conversely, a class III socket includes a compromised condition that requires multiple-stage reconstruction mostly suitable for standard delayed implant placement with alveolar ridge preservation. Within the limitations of this study, the new classification system not only provides comprehensive inclusion of various crucial parameters in implant placement (such as prediction of future implant position and osteotomy difficulty, etc.) but also, in contrast to the previously introduced systems, is able to classify the ES prior to extraction and also, takes into the account the patient-related factors as the class modifiers following the extraction.

Peri-implant bone resorption risk of anterior maxilla narrow single implants: a finite-element analysis

Statement of the problem: Narrow implants have been recommended in high esthetic demand regions to ensure greater buccal bone thickness (BBT) and minimize soft-tissue recession due to insufficient bone support. However, a limited area of bone-implant interface can increase the risk of peri-implant bone resorption due to occlusal forces. Purpose: This article encourages the use of evidence-based finite element analysis to optimize the aesthetic outcomes in maxillary lateral incisor single-supported implant crown by accurate biomechanical planning. This study aimed to analyze the best implant dimensions that would preserve the maximum BBT and avoid peri-implant bone resorption due to occlusal forces. Materials and methods: A maxilla segment was constructed based on anthropological measurements. Four implant diameters (Ø = 3.25; 3.50; 3.75 or 4.00 mm) and two lengths (L = 10 or 13 mm) were simulated. The occlusal force parameters were defined to simulate clinical conditions. The bone resorption risk analysis was based on Frost's mechanostat theory altering the strain output to strain energy density (SED). The peri-implant bone resorption risk indexes (PIBR_ri) were calculated by dividing the average of the top ten SED elements of the cortical and trabecular buccal wall by the pathologic resorption limit for each bone. Results: For trabecular bone, only the model Ø4.00_L13 exhibited a low PIBR_ri. For cortical bone, all models presented a low PIBR_ri, except for models Ø3.25. Conclusion: The selection of a 3.25 mm dental implant to preserve a 2 mm BBT should be avoided since it generates a high peri-implant bone resorption risk induced by occlusal overload.

Narrow-diameter implants versus regular-diameter implants for rehabilitation of the anterior region: a systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to evaluate studies comparing implant survival rates, marginal bone loss (MBL), and mechanical and biological complication rates between narrow-diameter implants (NDIs) and regular-diameter implants (RDIs) used for oral rehabilitation in the anterior region. The review was conducted according to the PRISMA checklist. Two independent reviewers performed a comprehensive search of the PubMed/MEDLINE, Embase, Scopus, and Cochrane Library databases for studies published until May 2020. A total of 843 implants (484 NDIs and 359 RDIs) were included. No significant difference in implant survival rate (risk difference (RD) 0.01, 95% confidence interval (CI) -0.01 to 0.03; P=0.34), MBL (standardised mean difference -0.51mm, 95% CI -1.29 to 0.26mm; P=0.19), mechanical complications (RD 0.01, 95% CI -0.02 to 0.04; P=0.40), or biological complications (RD 0.01, 95% CI -0.09 to 0.11; P=0.85) was found between the implant groups. Within the limitations of this study, it is concluded that NDIs are an effective alternative to RDIs due to similar survival rates, MBL, and mechanical and biological complication rates. However, future studies are highly encouraged due to the small number of interventional studies on this topic.

Biomechanical planning for minimally invasive indirect restorations

This paper explores the planning and execution of indirect partial-coverage restorations and will outline practical recommendations for maximising the outcomes for minimally invasive (MI) approaches to indirect restorations, with a special focus on vital teeth, endodontically-treated teeth and worn dentitions. Throughout the paper, the supporting evidence for each rationale for partial-coverage restorations will be considered, as well as the risks and benefits of adopting an MI approach to indirect restorations.

Failure Modes and Survival of Anterior Crowns Supported by Narrow Implant Systems

The reduced hardware design of narrow implants increases the risk of fracture not only of the implant itself but also of the prosthetic constituents. Hence, the current study is aimed at estimating the probability of survival of anterior crowns supported by different narrow implant systems. Three different narrow implant systems of internal conical connections were evaluated (Ø3.5 × 10 mm): (i) Active (Nobel Biocare), (ii) Epikut (S.I.N. Implant System), and (iii) BLX (Straumann). Abutments were torqued to the implants, and standardized maxillary incisor crowns were cemented. The assemblies were subjected to step-stress accelerated life testing (SSALT) in water through load application of 30 degrees off-axis lingually at the incisal edge of the crowns using a flat tungsten carbide indenter until fracture or suspension. The use level probability Weibull curves and reliability for completion of a mission of 100,000 cycles at 80 N and 120 N were calculated and plotted. Weibull modulus and characteristic strength were also calculated and plotted. Fractured samples were analyzed in a stereomicroscope. The beta (β) values were 1.6 (0.9-3.1) and 1.4 (0.9-2.2) for BLX and Active implants, respectively, and 0.5 (0.3-0.8) for the Epikut implant, indicating that failures were mainly associated with fatigue damage accumulation in the formers, but more likely associated with material strength in the latter. All narrow implant systems showed high probability of survival (≥95%, CI: 85-100%) at 80 and 120 N, without significant difference between them. Weibull modulus ranged from 6 to 14. The characteristic strength of Active, Epikut, and BLX was 271 (260-282) N, 216 (205-228) N, and 275 (264-285) N, respectively. The failure mode predominantly involved abutment and/or abutment screw fracture, whereas no narrow implant was fractured. Therefore, all narrow implant systems exhibited a high probability of survival for anterior physiologic masticatory forces, and failures were restricted to abutment and abutment screw.

Influence of time on primary stability of dental implants placed with osteotomes due to the elastic properties of peri-implant bone

Background/purpose

The use of osteotomes as a technique for densification and expansion of the residual ridge is one of the most widely used procedures to achieve adequate peri-implant bone quantity and density. The aim of this study was to evaluate the influence of time and the elastic deformation of peri-implant bone in the primary stability of implants placed using osteotomes.

Materials and methods

In each of 10 fresh fragments of cow rib, two implants were placed using osteotomes. The insertion torque and initial implant stability quotient (ISQ) values were measured. In the control implants, the immediate removal torque was measured, while in the test implants, after 15 min of placement, ISQ values were measured again, and the removal torque was measured.

Results

There were significant differences between the ISQ values and between the insertion torque and removal torque at 15 min. The ISQ values (perpendicular/parallel) increased between the initial moment (64.4 ± 9/70.3 ± 5.9) and 15 min (66/71.4 ± 6.4). The removal torque at 15 min (12.4 ± 5.8) was lower than the insertion torque (15.9 ± 5.9). Compression of the trabeculae in contact with the implant placed using osteotomes was observed, as well as a greater number of trabecular fractures in the implants placed using conventional drilling.

Conclusion

There is an increase in ISQ values of dental implants placed using osteotomes after 15 min of placement.

Therapeutic alternatives for addressing pink esthetic complications in single-tooth implants: A proposal for a clinical decision tree

OBJECTIVE

Esthetic complications in implant therapy today represent a clinical challenge, when the aim is to overcome the sequelae and obtain a pleasing result. The current scientific literature about this topic is scarce and often based on case reports and the personal opinions of clinicians.

CLINICAL CONSIDERATIONS

The aim of this article is to introduce a decision tree for diagnosis and treatment of complications, focusing on the pink esthetic of single-tooth implants and based on three diagnostic pillars (3D implant position, peri-implant hard-tissue anatomy, and peri-implant soft-tissue anatomy). Different shortcomings have been identified for each of the three diagnostic areas.

CONCLUSIONS

Following this tree, the article proposes treatment alternatives including soft- and hard-tissue reconstruction, implant submergence, orthodontic extrusion, and implant extraction in order to help clinicians establish a logical therapeutic sequence.

CLINICAL SIGNIFICANCE

Guidelines for adequate diagnosis and management of single implant-supported restorations with compromised esthetics is mandatory when attempt to overcome shortcoming in the pink esthetic result.

Relationship between anterior mandibular bone thickness and the angulation of incisors and canines-a CBCT study

OBJECTIVES

The morphology of the maxillary and mandibular alveolar cortex plays an important role in the planning of orthodontic treatment. Cone-beam computed tomography (CBCT) provides a precise demonstration of anatomical structures. Therefore, the aim of this paper was to evaluate what influence the position of incisors and canines have on the dimensions of the cortical and spongious bone of the anterior mandibular alveolar process.

MATERIALS AND METHODS

The material consisted of 100 CBCT volumes (61 females and 39 males, aged 18-71 years) obtained by means of a Gendex GXCB-500 machine and analysed using i-CAT Vision and CorelDRAW 9 software. Several linear and angular measurements were taken of cortical and spongious mandibular, vestibular and lingual alveolar bone.

RESULTS

The thickness of the vestibular spongious bone increased around lateral incisors and canines together with dental axis inclination, as did the thickness of the lingual spongious bone around central incisors and canines with greater angles of vestibular cortex curvature. In all teeth, the thickness of lingual cancellous bone decreased along with increase of the angle of tooth inclination. In the case of almost all groups of teeth, the thickness of lingual cancellous bone around teeth declined as the angle of curvature of the cortical bone decreased. The rotation of mandibular incisors and canines did not affect the thickness of the surrounding bone.

CONCLUSIONS

The position of teeth has little influence on vestibular bone thickness and is only significant around central incisors. In the case of almost all groups of teeth, the thickness of lingual spongious bone around teeth declined as the angle of curvature of the cortical bone decreased.

CLINICAL RELEVANCE

CBCT is a diagnostic tool that provides detailed information on the dimensions of the anterior dentate mandibular alveolar process.

[Current dental implant design and its clinical importance]

The development of clinical implant dentistry was intensively affected by dental implant design improvement and innovation, which brought about new concept, even milestone-like changes of clinical protocol. The current improvements of dental implant design and their clinical importance could be highlighted as followings: 1) The implant apical design influences the implant preliminary stability in immediate implant. The apical 3-5 mm design of implant makes implant stable in immediate implant, because this part would be screwed into alveolar bone through fresh socket, the other part of implant could not be tightly screwed in the socket because of smaller implant diameter. Implant apical form, screw design, self-taping of apical part would be essential for immediate implant. 2) The enough preliminary stability of implant makes immediate prosthesis possible. When osseointegration does not occur, the implant stability comes from a mechanical anchorage, which depends on implant form, screw thread and self-taping design. 3) Implant neck design may have influence for soft tissue recession in esthetic zone. The implant with large shoulder would not be selected for the esthetic area. The platform design may be more favorable in the area. 4) The connection design between implant and abutment is thought a very important structure in implant long-term stability. Moose taper and "tube in tube" were well documented structure design in 20-year clinical practice in Peking University. 5) In last 15 years, the plenty studies showed the platform design of implant had positive influence in implant marginal bone level. Whatever in single implant restoration or multi-implant prosthesis. 6) The digital technology makes clinical work more precise and high-tech. This would be a trend in implant dentistry. New generation of chair-side digital computer-aided design/computer-aided manufacturing makes immediate prosthesis without conventional impression possible. 7) New abutment design have changed clinical protocol greatly. The All-on-four concept and Weldone concept benefit both from the abutment innovation, which were large angulated abutment and special welding abutment materials.

Fatigue Failure of Narrow Implants with Different Implant-Abutment Connection Designs

PURPOSE

To evaluate the reliability of narrow diameter dental implants (NDIs) with similar macrogeometry and 3 implant-abutment connection designs.

MATERIALS AND METHODS

Eighty-four NDIs (3.5 × 10 mm) were selected and divided into 4 groups (n = 21/group) according to implant-abutment connection design, as follows: EH - external hexagon, IH - internal hexagon, IC - internal conical, and IC-M - internal conical connected to a monolithic titanium abutment. Identical abutments were torqued to the implants, and standardized maxillary incisor crowns were cemented and subjected to step-stress accelerated life testing (SSALT) in water. Use of level probability Weibull curves, and reliability for a mission of 50,000 cycles at 75 N and 200 N were calculated.

RESULTS

The beta (β) values were: 1.48 for IC, 1.40 for IC-M, 8.54 for EH, and 1.98 for IH, indicating that damage accumulation was an acceleration factor for failure of all groups. At 75 N the probability of survival was not significantly different between groups. A decrease in reliability was observed for all groups at 200 N with no significant differences between IC (81.71%) and IC-M (94.28%), or between EH and IH (0%) which presented the lowest values. EH failures were primarily restricted to the screw, while IH involved screw and implant fracture. IC and IC-M were restricted to prosthetic failures (fracture and bending).

CONCLUSIONS

Narrow implants with external or internal hexagon connections presented the lowest reliability at high loads compared to internal conical connections. Failure modes differed among connections.

Buccal bone thickness at dental implants in the aesthetic zone: A 1-year follow-up cone beam computed tomography study

Sufficient buccal bone thickness (BBT) is important for an optimal aesthetic outcome of implant treatment in the aesthetic zone. The aim of the study was to assess BBT at dental implants placed in the aesthetic zone (incisor, canine or first premolar in the maxilla) (immediate or delayed, with or without immediate provisionalization) with cone beam computed tomography (CBCT) as a function of time. Eighty patients were divided into 4 groups according to size of the buccal bony defect (<5 or ≥5 mm) after removal of the tooth, and timing of implant placement and provisionalization. CBCTs were made 1 month and 1 year after placement of the implant crown. BBT varied from 0.79 mm to 2.12 mm at 1 month and from 0.71 mm to 2.04 mm at 1 year. Change of BBT between 1 month and 1 year was negligible. This study concluded that BBT at dental implants in the aesthetic zone appears to be stable for immediate and delayed placed implants after placement of the definitive crown, independent of the size of buccal bone defect prior to implant insertion and timing of provisionalization.

Critical buccal bone dimensions along implants

The buccal bone plate is a component of the alveolar process tightly related to the tooth it supports. A plethora of physiological and pathological events can induce its remodeling. Understanding this remodeling process and its extent is of major importance for the practitioner as it can affect the functional and esthetic outcome of implant surgery at the involved sites. Bone remodeling and resorption of the buccal bone plate are inevitable after tooth loss or extraction. To limit resorption, several ridge-preservation techniques of varying efficacy have been described. Bone resorption is equally found to occur upon implant placement and is thought to be a result of the surgical trauma inflicted as well as an adaptation process of the tissues to the new foreign body. Because of the implications of bone resorption on the soft-tissue levels and the general esthetic outcome, it is of primary importance for the practitioner to be able to evaluate the hard tissues and the inherent resorption risks in an effort to optimize the treatment strategies. Based on limited short-term data, the present general opinion advises the need for a 2-mm-thick buccal bone plate in order to avoid vertical bone resorption.

Alterations of papilla dimensions after orthodontic closure of the maxillary midline diastema: a retrospective longitudinal study

PURPOSE

The aim of this study was to evaluate alterations of papilla dimensions after orthodontic closure of the diastema between maxillary central incisors.

METHODS

Sixty patients who had a visible diastema between maxillary central incisors that had been closed by orthodontic approximation were selected for this study. Various papilla dimensions were assessed on clinical photographs and study models before the orthodontic treatment and at the follow-up examination after closure of the diastema. Influences of the variables assessed before orthodontic treatment on the alterations of papilla height (PH) and papilla base thickness (PBT) were evaluated by univariate regression analysis. To analyze potential influences of the 3-dimensional papilla dimensions before orthodontic treatment on the alterations of PH and PBT, a multiple regression model was formulated including the 3-dimensional papilla dimensions as predictor variables.

RESULTS

On average, PH decreased by 0.80 mm and PBT increased after orthodontic closure of the diastema (P<0.01). Univariate regression analysis revealed that the PH (P=0.002) and PBT (P=0.047) before orthodontic treatment influenced the alteration of PH. With respect to the alteration of PBT, the diastema width (P=0.045) and PBT (P=0.000) were found to be influential factors. PBT before the orthodontic treatment significantly influenced the alteration of PBT in the multiple regression model.

CONCLUSIONS

PH decreased but PBT increased after orthodontic closure of the diastema. The papilla dimensions before orthodontic treatment influenced the alterations of PH and PBT after closure of the diastema. The PBT increased more when the diastema width before the orthodontic treatment was larger.

Three-Dimensional Analysis of the Anatomical Characteristics and Dimensions of the Nasopalatine Canal Using Cone Beam Computed Tomography

AIM

Placement of implants in the maxillary anterior region needs to be preceded by careful analysis of the area as in addition to the functional aspect the esthetic outcome is of prime importance. This descriptive study evaluated anatomical characteristics and dimensions of the nasopalatine canal (NC) from coronal, sagittal and axial aspects using cone beam computed tomography (CBCT) giving it a three dimensional analytical approach. Also the dimensions of the corresponding buccal bone plate (BBP) of the alveolar process were evaluated. Additionally, the influence of age and gender on these characteristics was also analyzed.

METHODS

A total of 81-CBCT scans of patients with one or no upper central incisors present were selected. Sagittal slices were used for measurements of the NC and BBP and to evaluate shape of the NC. Coronal slices were used to assess NC shape and axial slices to assess number of incisive foramina and foramina of Stenson.

RESULTS

The most prevalent canal shape was: cylindrical (48.14 %) in sagittal aspect; Y-type (49.38 %) in coronal aspect; and one incisive foramen with two Stenson's foramina [1-(2-5)] (60.49 %) in axial aspect. Mean NC length was 11.13 ± 3.23 mm; statistically significant differences were detected between genders (p < 0.001). Mean nasopalatine angle was 69.32° ± 7.70. Mean BBP length was 17.12 ± 3.97 mm and mean BBP width was 5.71 ± 1.29 mm, significant differences were detected between genders (p < 0.001).

CONCLUSION

The current study demonstrates variability of the NC in terms of anatomical characteristics and dimensions; hence, a thorough CBCT analysis is highly recommended for better surgical outcomes and to reduce the post-operative complications in implant dentistry.

Evaluation of peri-implant buccal bone by computed tomography: an experimental study

OBJECTIVES

To evaluate the accuracy of measuring peri-implant buccal bone when using three different computed tomography devices.

MATERIALS AND METHODS

Sixty tissue-level or bone-level dental implants were placed in bovine ribs with either buccal bone full coverage, dehiscence or fenestration. For each site, the distance from the bone defect to the implant neck and the buccal bone thickness 1 mm apical to the crest were measured using a calliper. Subsequently, all sites were scanned in a reproducible position using a multi-slice computed tomography (CT) (Brightspeed, voxel size 0.625 mm) and two cone-beam computed tomography devices (i-CAT NG, voxel size 0.3 mm and Newtom VGi, voxel size 0.2 mm). Bone thickness was measured on images from the three systems similar to direct measurements and differences were evaluated. Factors that could influence the buccal bone identification were assessed by multiple binary logistic regression.

RESULTS

Buccal bone ranged from 0.1 mm to 2.75 mm in thickness and was not visible in 68%, 63% and 60% of cases when using CT, i-CAT and Newtom, respectively. For each mm of bone thickness increment, the odds of radiographic identification increased by 30.6 (P < 0.001). Bone defects negatively affected radiographic visibility (P < 0.05). All devices underestimated bone dimensions although differences among them were not significant.

CONCLUSIONS

Within these experimental conditions, the investigated devices have equivalent low accuracy in diagnosing peri-implant buccal bone. Accuracy was significantly influenced by buccal bone thickness, especially if <1 mm, and in presence of peri-implant marginal defects.

Predictors of Alveolar Process Remodeling Following Ridge Preservation in High-Risk Patients

PURPOSE

(1) To clinically evaluate horizontal remodeling of the alveolar process (hard and soft tissues) following ridge preservation in high-risk patients and (2) to identify predictors of such remodeling.

MATERIALS AND METHODS

Periodontally healthy nonsmoking patients with a failing tooth in the anterior maxilla (15-25) were selected for a prospective case series. All were in need of a single implant and demonstrated high risk for aesthetic complications given an incomplete buccal bone wall and/or thin-scalloped gingival biotype. Following flapless tooth extraction, ridge preservation was performed using one or more collagen-enriched, bovine-derived block grafts (Geistlich Bio-Oss® Collagen® 100 mg, Geistlich Pharma AG, Wolhusen, Switzerland) without the additional use of membranes or soft tissue grafts. The change in buccopalatal dimension of the alveolar process between baseline (prior to tooth extraction) and 4 months was assessed on the basis of superimposed occlusal slides. Regression analysis was performed to identify predictors of alveolar process remodeling.

RESULTS

Forty-two patients (21 females, 21 males; mean age 38) met the selection criteria and consented to the treatment. Mean alveolar process remodeling was 14% (SD 7, range 4-30) with minimal remodeling (≤ 10%) in 16 patients (38%) and advanced remodeling (>20%) in 10 patients (24%). A single implant could be installed in all subjects without additional guided bone regeneration. Connective tissue grafting was performed later on in the treatment for aesthetic purposes, hereby compensating for tissue loss at the buccal aspect. Predictors of alveolar process remodeling were tooth location (central incisors and cuspids > laterals incisors and premolars), tooth abscess (p = .025), and buccal bone loss (p = .035).

CONCLUSION

Alveolar process remodeling seems inevitable yet acceptable following ridge preservation in high-risk patients. Proper case selection may reduce the incidence of advanced remodeling.

Single implant-supported crowns in the aesthetic zone: patient satisfaction with aesthetic appearance compared with appraisals by laypeople and dentists

OBJECTIVE

To appraise the patients' satisfaction with aesthetic outcomes following an implant restoration in the anterior maxilla as compared to appraisals made by dentists and laypeople.

MATERIAL AND METHODS

Randomly selected patients (n = 116) restored with an implant-retained crown in the anterior maxilla were invited to rate their satisfaction with aesthetic outcomes using a questionnaire containing seven criteria, each graded from excellent to poor. Projected images of the patient smiles were appraised by dentists (n = 8) and laypeople (n = 6) using the same assessment criteria in a room setting. In addition, the laypeople judged the same cases on printed 10 × 15 cm photographs in a separate setting. Jemt papilla scores, pink aesthetic score (PES) and white esthetic score (WES) were assigned by the dentists. Differences in the levels of satisfaction between the patient, and appraisals by the dentists and the laypeople were compared using non-parametric statistical tests.

RESULTS

Patients' opinions of their aesthetic appearance following the placement of a single implant-supported crown in the aesthetic zone were in general very favourable. The laypeople were more critical than the dentists when the aesthetic outcomes were appraised on magnified images projected onto a screen. Laypeople became less critical when evaluating the aesthetic outcomes on printed photographs compared to appraisals on a screen. Patient satisfaction with their aesthetic appearance differed from dentists' and laypeople's appraisals.

CONCLUSION

Factors other than the actual aesthetic outcome itself appear to influence patients' satisfaction with their end results. Laypeople's appraisal is influenced by the magnification and method used for appraising the aesthetic outcomes.

Cone-beam computed tomographic analysis of the morphological characterization of the nasopalatine canal in a pediatric population

PURPOSE

Knowledge of the nasopalatine canal (NPC) is necessary for understanding the morphology and pathogenesis of lesions that occur in this region. The purpose of the present study was to analyze the dimensions and anatomic characteristics of the NPC in a pediatric population using cone-beam computed tomography (CBCT).

STUDY DESIGN

Reformatted sagittal, coronal, and axial slices of 368 individual CBCT images were analyzed with regard to dimensions and anatomic features of the NPC.

RESULTS

Funnel shape of the NPC was most commonly found [26.9 % (99)], followed by banana shape [19.6 % (72)]. There was no statistically significant difference (p = 0.317) between girls and boys in terms of NPC shape. The mean width of incisive foramen was found to be 2.53 mm with a significant difference (0.002). The mean NPC length was found to be 10.83 mm and the mean canal length was found to be significantly longer in boys than girls (p < 0.000).

CONCLUSION

The present study provides new information on the literature concerning the identification of the anatomical structure of NPC. This finding may assist clinicians in understanding the morphology and preventing possible complications in this region.

Evaluation of the nasopalatine canal and variations with cone-beam computed tomography

PURPOSE

Although nasopalatine canal (NPC) is one of the most important anatomical structures in premaxillary region, few documents are available with regard to anatomic variations, size, and morphology of NPC in the literature. In recent years, the need for radiological identification of anatomical structures has grown with increased dental implant applications in anterior maxillary region with higher esthetic expectations. This study aimed at investigating the NPC's shape and anatomical variations by cone-beam computed tomography (CBCT) in the Turkish society, in a particular region.

METHODS

A total of 500 individual CBCT images were investigated in terms of morphological, dimensional, and anatomical features of NPC. In addition, the width of incisive foramen (IF) and foramina of Stenson were evaluated.

RESULTS

There was no statistically significant difference (p = 0.234) between women and men in terms of NPC shape. Morphological assessment of NPC revealed that 38.78 % of NPCs were hourglass-like in shape, 27.35 % of canals were funnel-shaped, 9.18 % of canals were conical shaped, and 8.25 % of canals were cylindrical shaped. The mean IF width and NPC length was found as 5.06 and 12.59 mm, respectively. And the mean canal length was found significantly longer in men than women (p < 0.001).

CONCLUSION

It has been shown that NPC has a lot of anatomical variations with regard to its dimensions as well as its morphological appearance. Therefore, identification of the anatomical structure of this region with two- and three-dimensional imaging techniques maybe thought to be important in facilitating surgical management and preventing possible complications.

Anterior maxillary and mandibular biotype: relationship between gingival thickness and width with respect to underlying bone thickness

PURPOSE

: Periodontal biotype is considered to be a significant factor related to successful dental treatments. The purpose of this study was to determine the relationship between gingival thickness (GT) and width with respect to the underlying bone thickness in the maxillary and mandibular anterior sextant.

MATERIALS AND METHODS

: Overall, 180 anterior teeth within healthy patients were assessed. GT and buccal bone thickness (BT) were measured at 3 locations: crestal/gingival margin, tooth apex, and a midpoint between the 2. In addition, the apicoincisal gingival width (GW) was recorded. Clinical and cone beam CT measurements were compared and correlated.

RESULTS

: No statistically significant relations were observed between GT and BT measures at any of the 3 positions. The mean GT at crestal mid and apical position for the maxillary teeth was 1.01 (±0.58) mm, 1.06 (±0.48) mm, and 0.83 (±0.47) mm, respectively, and the corresponding mean BT was 1.24 (±0.90) mm, 0.81 (±0.33) mm, and 2.78 (±1.62) mm, respectively. The GW is directly related (R = 0.007; P < 0.05) to the crestal BT.

CONCLUSION

: In this study, the GT is not linked to the BT. However, the GW seems to be associated with the crestal BT.

Hard and soft tissue changes around implants installed in regular-sized and reduced alveolar bony ridges. An experimental study in dogs

OBJECTIVE

To study bony and soft tissue changes at implants installed in alveolar bony ridges of different widths.

MATERIAL AND METHODS

In 6 Labrador dogs, the mandibular premolars and first molars were extracted, and a buccal defect was created in the left side at the third and fourth premolars by removing the buccal bone and the inter-radicular and interdental septa. Three months after tooth extraction, full-thickness mucoperiosteal flaps were elevated, and implants were installed, two at the reduced (test) and two at the regular-sized ridges (control). Narrow or wide abutments were affixed to the implants. After 3 months, biopsies were harvested, and ground sections prepared for histological evaluation.

RESULTS

A higher vertical buccal bony crest resorption was found at the test (1.5 ± 0.7 mm and 1.0 ± 0.7 mm) compared to the control implants (1.0 ± 0.5 mm and 0.7 ± 0.4 mm), for both wide and narrow abutment sites. A higher horizontal alveolar resorption was identified at the control compared to the test implants. The difference was significant for narrow abutment sites. The peri-implant mucosa was more coronally positioned at the narrow abutment, in the test sites, while for the control sites, the mucosal adaptation was more coronal at the wide abutment sites. These differences, however, did not reach statistical significance.

CONCLUSIONS

Implants installed in regular-sized alveolar ridges had a higher horizontal, but a lower vertical buccal bony crest resorption compared to implants installed in reduced alveolar ridges. Narrow abutments in reduced ridges as well as wide abutments in regular-sized ridges yielded less soft tissue recession compared to their counterparts.

Analysis of the embrasure dimensions between maxillary central incisors in relation to the topography of the interdental papilla

Purpose

To analyze the dimensions of the embrasure space between the maxillary central incisors as potential factors influencing interdental papilla fill and height.

Methods

The embrasure dimensions between the maxillary central incisors of 100 subjects (40 females/60 males) were assessed with clinical, study model, and radiographic examinations. Variables of the complete and deficient papilla fill groups were compared. Multiple regression analyses were performed to investigate potential influence of the distance between the contact point and bone crest (CP_BC), horizontal interdental distance (HID), and facio-lingual thickness (FLT) at the papilla base on complete/deficient papilla fill and papilla height (PH).

Results

CP_BC was the only variable that showed a significant difference between the complete and deficient papilla groups (P<0.05). When the CP_BC was less than 5 mm, the embrasure spaces between the maxillary central incisors were completely filled with interdental papilla. Multiple regression analyses revealed that a significant predictor for complete/deficient papilla fill was CP_BC, and significant predictors for PH were CP_BC and HID (P<0.05).

Conclusions

The chances of complete papilla fill increased as CP_BC decreased, while PH increased as CP_BC and HID increased. However, the FLT of the papilla base did not appear to affect papilla fill or PH. From an esthetic perspective, CP_BC as well as HID should be considered as factors influencing the topography of interdental papilla.

Stress distribution around maxillary anterior implants as a factor of labial bone thickness and occlusal load angles: a 3-dimensional finite element analysis

The purpose of this study was to evaluate the influence of the stress/strain distribution in buccal bone of an anterior maxillary implant using 3 bone thicknesses under 5 different loading angles. Different testing conditions incorporating 3 buccal bone thicknesses, 3 bone compositions, and 5 loading angles of an anterior maxillary implant were applied in order to investigate the resultant stress/strain distribution with finite element analysis. The maximum equivalent stress/strain increased with the decreasing of loading angle relative to the long axis. In addition to loading angle, bone quality and quantity also influenced resultant stress distribution. Dental practitioners should consider combinations of bone composition, diameter, and load angulations to predict success or failure for a given implant length and diameter.

Tissue augmentation and esthetics (Working Group 3)

INTRODUCTION

The remit of this working group was to update the existing knowledge base regarding bone augmentation for implant site development and soft-tissue grafting for esthetic outcomes. Four reviews from the working group formed the basis of this update. Moreover, clinical applications as well as suggestions for further research have been formulated.

MATERIALS AND METHODS

The papers in the working group critically reviewed the literature. Four manuscripts were produced assessing (a) the outcomes of correcting dehiscence and fenestration defects at implant sites using various graft materials, (b) the outcomes of sinus floor augmentation at maxillary posterior sites with 6 mm or less residual bone height using various graft materials, (c) the association of the horizontal dimensions of buccal and interproximal bone with esthetic outcomes of implant-supported restorations, and (d) the outcomes of soft-tissue augmentations.

RESULTS

The results and conclusions of the review process are presented in the following papers. The group's consensus statements, clinical implications, and directions for future research are presented in this article.