B. Alper Gultekin

Influence of Arch Shape and Implant Position on Stress Distribution Around Implants Supporting Fixed Full-arch Prosthesis in Edentulous Maxilla

Purpose:This finite element analysis was conducted to determine changes in stress concentration in relation to different alveolar arch shapes of the maxilla. Materials and Methods:Five different maxillary alveolar arch shape measurements coded as shortest ellipsoid shape and medium width, longest ellipsoid shape and narrow, U-shaped long and narrow, U-shaped short and wide, and U-shaped medium length and medium width were obtained, and 5 different implant distribution strategies coded on the basis of a tooth number as 3,4,5; 2,3,4; 1,3,5; and 2,4,5 (total of 6 implants) and 2,3,4,5 (total of 8 implants) were plotted in each of the 5 maxillary arch models. The implants were assumed to support a 12-unit bridge with first molars region being the cantilever area. Combination of 5 different arch shapes, 5 different implant distributions, and 2 different loading points (anterior and posterior) led to 50 different simulated scenarios that are all solved and compared. Results:In case of either anterior or posterior loading, the most favorable implant distribution strategies for the arch models are as follows: 2,4,5 and 2,3,4,5 for longest ellipsoid shape and narrow; 2,4,5 and 2,3,4,5 for shortest ellipsoid shape and medium width; 1,3,5 and 2,3,4,5 for U-shaped long and narrow; 2,3,4,5 and 2,4,5 for U-shaped medium length and medium width; and 1,3,5 and 2,3,4,5 for U-shaped short and wide. Conclusions:Distribution of implants in 2,4,5 order seemed to be fairly favorable for ideal stress distribution in all simulated models.

Effect of crown to implant ratio and implant dimensions on periimplant stress of splinted implant-supported crowns: a finite element analysis.

Purpose:To assess the influence of different crown-implant (C/I) ratios and implant dimensions on periimplant stress in the partially edentulous posterior mandible by 3-dimensional finite element analysis (FEA). Materials and Methods:Two implants were placed in the second premolar and first molar regions of the mandibular model. The implants were then splinted with a 2-unit fixed bridge. The influence of 3 parameters (C/I ratio, implant length, and implant diameter) on periimplant bone stress was then analyzed by using FEA. Results:C/I ratios showed a direct relationship with periimplant bone stress, but the absolute height of the clinical crown had a much more significant influence. The implant length had less influence on the periimplant bone stress than the implant diameter. Lower stress values were detected in wide-diameter implants, even in scenarios involving long crowns. Conclusions:Crown height is a more important factor affecting the periimplant bone stress than the C/I ratio for splinted implant-supported crowns. Two-unit fixed restorations with high C/I ratios may be successfully used with wide-diameter implants in the posterior mandible.

Evaluation of Volumetric Changes of Augmented Maxillary Sinus With Different Bone Grafting Biomaterials.

AbstractExtensive alveolar bone resorption because of pneumatized maxillary sinus is a common problem that limits dental implant placement. Maxillary sinus floor augmentation (MSFA) is an accepted treatment protocol that provides sufficient bone volume. The aim of this study was to evaluate the percentage of graft volume reduction following MSFA using cone beam computed tomography. In this retrospective study, cone beam computed tomography scans of MSFA were measured to evaluate the volume of the grafted sinus with deproteinized bovine bone (DBB), mineralized allograft (MA), or a mixture of MA and demineralized allograft as a composite. The volumetric changes in sinus augmentation between 2 weeks (T-I) and 6 months (T-II) after operation were analyzed. Thirty-nine patients were included in this study. The average percent volume reduction was 8.14 ± 3.76%, 19.38 ± 9.22%, and 24.66 ± 4.68% for DBB, MA, and composite graft, respectively. A significant graft volume reduction was found between T-I and T-II for all groups (P < 0.01). The DBB group showed the least volume reduction (P < 0.01). Biomaterials can influence the bone graft volume change before implant placement. Deproteinized bovine bone may offer greater volume stability during healing than mineralized and composite allografts.

Application of Finite Element Analysis in Implant Dentistry

Since Brånemark’s discovery, dental implants have become the most common restorative technique for the rehabilitation of edentulism. Many factors can impact the survival of implant-supported restorations. The most important factor for determining the long-term success of osseointegration is the state of the peri-implant bone [1-3]. Ideal biomechanical conditions directly affect bone remodeling and help to maintain the integrity of non-living structures such as the implant, abutment, and superstructures (Figures 1-7). Oral dental implant interventions involving surgical and restorative procedures for the rehabilitation of various causes of edentulism are associated with several risks. In particular, mechanical and technical risks plays a major role in implant dentistry, resulting in increased rates of repairs, unnecessary costs and lost time, and even complications that may not be easily corrected (Figures 8-10) [4-7]. Therefore, the potential mechanical and technical risks of failure or associated complications need to be evaluated before undertaking such interventions, since the application of necessary precautions may improve the survival of implant-supported restorations. Consequently, the number of biomechanical studies in the field of implant dentistry has dramatically increased in an effort to reduce failure rates.

Comparison of Bone Resorption Rates after Intraoral Block Bone and Guided Bone Regeneration Augmentation for the Reconstruction of Horizontally Deficient Maxillary Alveolar Ridges

Purpose. Bone atrophy after tooth loss may leave insufficient bone for implant placement. We compared volumetric changes after autogenous ramus block bone grafting (RBG) or guided bone regeneration (GBR) in horizontally deficient maxilla before implant placement. Materials and Methods. In this retrospective study, volumetric changes at RBG or GBR graft sites were evaluated using cone-beam computed tomography. The primary outcome variable was the volumetric resorption rate. Secondary outcomes were bone gain, graft success, and implant insertion torque. Results. Twenty-four patients (28 grafted sites) were included (GBR, 15; RBG, 13). One patient (RBG) suffered mucosal dehiscence at the recipient site 6 weeks after surgery, which healed spontaneously. Mean volume reduction in the GBR and RBG groups was 12.48 ± 2.67% and 7.20 ± 1.40%, respectively. GBR resulted in significantly more bone resorption than RBG (P < 0.001). Mean horizontal bone gain and width after healing were significantly greater in the GBR than in the RBG group (P = 0.002 and 0.005, resp.). Implant torque was similar between groups (P > 0.05). Conclusions. Both RBG and GBR hard-tissue augmentation techniques provide adequate bone graft volume and stability for implant insertion. However, GBR causes greater resorption at maxillary augmented sites than RBG, which clinicians should consider during treatment planning.

Three-Dimensional Assessment of Volumetric Changes in Sinuses Augmented with Two Different Bone Substitutes

Introduction. The bone volume of the posterior maxilla may not be appropriate for implant placement, due to factors such as pneumatized maxillary sinus. The purpose of this study was to evaluate the percentage of graft volume reduction following sinus floor elevation (SFE), with either slow resorbable bone substitute only or a composite of slow and fast resorbable bone substitutes, using cone beam computed tomography (CBCT). Materials and Methods. In this retrospective study, CBCT scans of SFE procedures were evaluated to determine the volume of grafted sinus with either deproteinized bovine bone (DBB) or a 2 : 1 mixture of biphasic calcium sulfate (CS) and DBB, as a composite. The volumetric changes of sinus augmentations were measured 2 weeks (V-I) and 6 months (V-II) after operation. Results. Thirty-three patients were included in this study. The average percentage volume reduction was 9.39 ± 3.01% and 17.65 ± 4.15% for DBB and composite grafts, respectively. A significant graft volume reduction was observed between V-I and V-II for both groups (p < 0.01). The DBB group exhibited significantly less volume reduction than the composite group (p < 0.01). Conclusions. Augmented sinus volume may change before implant placement. DBB offers greater volume stability during healing than composite grafts.

Does the Laser-Microtextured Short Implant Collar Design Reduce Marginal Bone Loss in Comparison with a Machined Collar?

Purpose. To compare marginal bone loss between subgingivally placed short-collar implants with machined collars and those with machined and laser-microtextured collars. Materials and Methods. The investigators used a retrospective study design and included patients who needed missing posterior teeth replaced with implants. Short-collar implants with identical geometries were divided into two groups: an M group, machined collar; and an L group, machined and laser-microtextured collar. Implants were evaluated according to marginal bone loss, implant success, and probing depth (PD) at 3 years of follow-up. Results. Sixty-two patients received 103 implants (56 in the M group and 47 in the L group). The cumulative survival rate was 100%. All implants showed clinically acceptable marginal bone loss, although bone resorption was lower in the L group (0.49 mm) than in the M group (1.38 mm) at 3 years (p < 0.01). A significantly shallower PD was found for the implants in the L group during follow-up (p < 0.01). Conclusions. Our results suggest predictable outcomes with regard to bone loss for both groups; however, bone resorption was less in the L group than in the M group before and after loading. The laser-microtextured collar implant may provide a shallower PD than the machined collar implant.

Removal of Deeply Impacted Mandibular Molars by Sagittal Split Osteotomy.

Mandibular third molars are the most common impacted teeth. Mandibular first and second molars do not share the same frequency of occurrence. In rare cases the occlusal surfaces of impacted molars are united by the same follicular space and the roots pointing in opposite direction; these are called kissing molars. In some cases, a supernumerary fourth molar can be seen as unerupted and, in this case, such a supernumerary, deeply impacted fourth molar is seen neighboring kissing molars. The extraction of deeply impacted wisdom molars from the mandible may necessitate excessive bone removal and it causes complications such as damage to the inferior alveolar nerve and iatrogenic fractures of the mandible. This case report describes the use of the sagittal split osteotomy technique to avoid extensive bone removal and protect the inferior alveolar nerve during surgical extruction of multiple impacted teeth.

FARKLI SİMANLARIN İMPLANTÜSTÜ KURON PROTEZLERİNİN TUTUCULUĞUNA ETKİSİEffect of Cement Type on Retention of Implant-Supported Crowns

oz Amac: Calismanin amaci, restorasyonlari implant postuna yap istirma amaciyla ozel olarak uretilmis recine bazli simandan tutuculuk direnci acisindan geleneksel simanlarla karsilastirmaktir. Gerec ve Yontem: Standart istirma amaciyla ozel olarak uretilmis recine bazli simandan tutuculuk direnci acisindan geleneksel simanlarla karsilastirmaktir. Gerec ve Yontem: Standart istirma amaciyla ozel olarak uretilmis recine bazli simandan tutuculuk direnci acisindan geleneksel simanlarla karsilastirmaktir. Gerec ve Yontem: Standart Oneway Anova ve Tukey HSD testleri yard imiyla 95% guven araliginda degerlendirildi. Bulgular: Gruplarin tutuculuk duzeyleri arasinda istatistiksel olarak ileri duzeyde anlamli farklilik bulundu (p<0.01). Sunanlarin retansiyon degerleri en dusukten yuksege dogru su sekilde siralandi: TB (39,65±8,08 N), Sonuc: Implant-destekli protezlerin simantasyonu icin ozel olarak gelistirilen recine bazli simanlar, geleneksel gecici simana oranla daha yuksek, geleneksel daimi simana gore ise daha dusuk retantif ozelliklere sahiptir. Anahtar kelimeler: Simantasyon, tutuculuk, implant-destekli kuron, gecici siman, daimi siman imiyla 95% guven araliginda degerlendirildi. Bulgular: Gruplarin tutuculuk duzeyleri arasinda istatistiksel olarak ileri duzeyde anlamli farklilik bulundu (p<0.01). Sunanlarin retansiyon degerleri en dusukten yuksege dogru su sekilde siralandi: TB (39,65±8,08 N), Sonuc: Implant-destekli protezlerin simantasyonu icin ozel olarak gelistirilen recine bazli simanlar, geleneksel gecici simana oranla daha yuksek, geleneksel daimi simana gore ise daha dusuk retantif ozelliklere sahiptir. Anahtar kelimeler: Simantasyon, tutuculuk, implant-destekli kuron, gecici siman, daimi siman imiyla 95% guven araliginda degerlendirildi. Bulgular: Gruplarin tutuculuk duzeyleri arasinda istatistiksel olarak ileri duzeyde anlamli farklilik bulundu (p<0.01). Sunanlarin retansiyon degerleri en dusukten yuksege dogru su sekilde siralandi: TB (39,65±8,08 N), Sonuc: Implant-destekli protezlerin simantasyonu icin ozel olarak gelistirilen recine bazli simanlar, geleneksel gecici simana oranla daha yuksek, geleneksel daimi simana gore ise daha dusuk retantif ozelliklere sahiptir. Anahtar kelimeler: Simantasyon, tutuculuk, implant-destekli kuron, gecici siman, daimi siman ABSTRACT Purpose: The aim of this study is to compare the retentive strength of implant cements with conventionally used cements. Materials and Methods: Standard titanium abutment was scanned by means of a 3D digital laser scanner. 40 standard metal copings were designed by a CAD/CAM system. Copings were cemented to the abutments using 1 of 4 luting cements (n=10) as (1) Premier Implant Cement (PIC), (2) TempBond NE (TB), (3) Multilink Implant (MI), (4) Adhesor Carbofine (AC). Copings were subjected to a pull-out test using a universal testing machine at a crosshead speed of 0.5 mm/min. Decementation load was analyzed with Oneway Anova and Tukey HSD tests at a confidence interval of 95%. Results: Cement groups showed statistically significant difference (p<0.01). Mean retentive strength of the groups were ranked as : TB (39,65±8,08 N), PIC (136,97±21,75 N), MI (301,60±28,43 N), AC (386,78±52,63 N). Conclusions: Decementation loads for the cements specifically formulated for usage with implant-supported restorations, were higher than that of conventional temporary cement and lower than that of conventional permanent cement. Keywords: Cementation, retention, implant-supported crown, provisional cement, permanent cement