Aim The aim of this article is to describe an alternative rehabilitation of a facially shifted postextraction implant with immediate provisionalization of a screw-retained restoration. Case report Immediate postextraction implant placement may pose significant challenges. A case is described where, despite proper risk assessment and planning, an implant shifted from the position of the prosthetic driven restoration. This resulted in different positions of immediate postextraction implants in the sites of the upper central incisors. The provisional was constructed with different access holes. The use of an angulated screw channel compensated the access holes from the original implant axis, thus making a screw-retained restoration on the palatal side feasible. Result The use of angulated screw-retained crowns might benefit periimplant condition in the long-term by eliminating the use of cements. Although the mechanical complications are underreported, this approach is likely to yield good results and allow shifted implant in the anterior region. Conclusions Angulated screw crowns could correct facially shifted implants in the esthetic zone. The system compensates the natural angulation of maxillary teeth, allows easy application of screw retained crowns, eliminates the risk of cement-related periimplantitis and preserves esthetics.

Aim The reduction in the amount of marginal bone is the most important demand for the long term success of dental implants. This prospective clinical study was aimed to investigate the marginal bone loss of early loaded SLActive implants with different dimensions and surgical approaches. Materials and methods Fifteen patients aged from 18 to 60 years were divided into 2 groups (flapped and flapless approach) that underwent delayed implant placement protocol with SLActive implants. The marginal bone level was estimated by cone-beam computed tomography during three different periods: preoperatively, 8 weeks after surgery and 24 weeks after loading of the prosthesis. Results The mean value of marginal bone level was not significantly changed 8 weeks after surgery and 12 weeks after loading of the prosthesis when compared with baseline data in both flapped and flapless approach. Bone level was significantly decreased with dental implant dimension A˜ 4.1 mm RC, length 12 mm. Conclusion The results demonstrated that marginal bone loss is affected by many factors, such as age of the patient, and dental implant dimension.

Aim This pilot preclinical study assessed applying thermal energy to osseo-disintegrate dental implants, minimizing collateral damage. Materials and methods Two experiments were designed. In the first one, thermal energy from a commercially available dental monopolar electro-scalpel (PerFect® TCS II) was applied to 55 Neodent® Titamax implants inserted in pig ribs (ex vivo), assessing temperature rise on the surrounding bone. The second one used the same thermal energy source and dental implants on an in vivo rabbit tibiae model (8 rabbits, 2 implants per tibiae, 5 months healing). Osseointegration measurements were ISQ, and removal torque values (RTV). After healing, implants from the first 5 rabbits were randomly treated with no thermal energy, 5 and 10s application. Seven days later, implants were measured, rabbits euthanized, and histology samples obtained. Three rabbits went through a second thermal application (15s). Results Temperatures after 5s were 84.6 ± 18.6°C, and 94.3 ± 22.0°C for 10s application (p<0.001). RTV and ISQ remained unchanged after 5s or 10s of thermal energy application. Nevertheless, after 15s, a tendency for a lower RTV could be observed. Histology confirmed an area of bone destruction. Conclusions Temperatures produced by different thermal application protocols are reported, thus filling a knowledge void. Extended time applications, monocortical insertion, and waiting more than one week for bone necrosis could decrease RTV in further studies. These data are essential in developing safe clinical implant removal tools.

Aim The present in vitro study aimed to evaluate the effect of different dental implant macrodesigns on the stress occurred on the implants and bone for two-implant-supported overdentures (IOD) in the rehabilitation of edentulous mandibles. Methods Six different implant brands and macro design were used in this study. Two groups, Group V (V-thread shape) and Group R (reverse buttress thread shape), were formed based on implant thread shape. Vertical and oblique loads were applied to the implants in order to evaluate tension, compression, and Von Mises stresses by implementing the three-dimensional finite element analysis. Results According to the stresses after the applied forces, the macrodesign of dental implants affects stress distribution in different directions. Group R exerted more stresses on the cortical bone, while Group V produced more stresses on the implants. Tissue level implants caused high stresses on bones and low stress on itself. As proposed, microthread neck design decreased the stresses on the cortical bone. Conclusion In the light of these biomechanical findings, considering the anterior region of the mandible often consists of dense cortical bone, it may be advantageous to prefer implants with a V-thread design and a microthread neck surface, which creates less stress in the cortical bone.

Aim To overcome vertical deficiency of atrophic posterior maxilla, sinus floor elevation has been used for several decades either through a transcrestal or a lateral approach. In 1999, Fugazzotto et al. described a modified trephine/osteotome technique for sinus floor augmentation at the time of maxillary molar extraction without implant placement. A trephine was used to create a bone core in the middle of the extraction site and was gently malleted apically. In 2002, Fugazzotto et al. used the same principle to place dental implants in healed maxillary molars sites with limited residual height (RH). This procedure demonstrated a 98.3% implant survival rate at 4 years but lacked radiographic information. The aim of the present study was to assess the efficacy of the modified trephine/osteotome sinus elevation with implant placement, using a clinical and a radiographic cone beam evaluation. Materials and methods Twenty-one implants were placed in premolar and molar sites with 3≤ RH ≤6mm using the modified trephine/osteotome sinus elevation approach and were evaluated clinically and radiographically at baseline (T1), 3 (T3) and 8 (T8) months. Results Implant survival was 100% at 8 months. Sub-antral volumetric bone gain between T1 and T8 was 20.34%. Linear bone gain was 2.1 ± 1.1 mm buccally; 2.0 ± 1.4 mm palatally; 2.5 ± 1.6 mm mesially; and 1.5 ± 1.5 mm distally. Mean linear bone gain was 2.0±1.1 mm calculated on the CBCT. Implant stability quotient (ISQ) at T1 was 66.378±7.931, and 67.921±14.369 at T3 without a statistically significant difference between the two measurements. Residual height was positively correlated to vestibular, palatal, and mesial bone gain. Signs of Schneiderian membrane tearing were noticeable in one case. Conclusion This study demonstrated that sufficient subantral bone formation can be obtained with the modified trephine/osteotome technique with high implant survival rate and low post-operative morbidity.

Aim The aim of the present review was to assess scientific literature on influence of clinical and technical parameters of guided implantation on implant position deviations. Methods Two reviewers conducted electronic searches on Cochrane and PubMed databases and manual search in databases of relevant scientific journals. The date range was limited to from 2009 through 2019. Results In total 36 publications were included for review and subgroup analysis. Meta-analysis revealed mean deviation of 1.14 mm (95% CI: 1.016, 1.268, SE: 0.064) at implant neck, 1.42 mm (95% CI: 1.275, 1.575, SE: 0.072) at implant apex as well as 0.415 mm (95% CI: 0.317, 0.514, SE: 0.096) of mean vertical error and 3.49° (95% CI: 3.228, 3.756, SE: 0.135) of mean angular error. Significantly lower deviations in one or more measurement points were determined in subgroups of partial edentulism, single implantation per guide, mechanical vertical control, mounted drill design and teeth-supported guides. Conclusion With respect to limitations of the study, it can be concluded that type of edentulism, size of defect, type of vertical control, guide design and type of guide support influence accuracy of computer-assisted guided implantation. Future research should focus on analyzing the advantages of technical parameters of individual static guides in distinct clinical subgroups.

Aims To analyze the survival rate of small-diameter implant (SDI) retained overdenture and evaluate the implant and attachment complications, as well as prosthetic maintenances, over a follow-up period of ≤4.5 years. Materials and methods Implant placement procedures were performed by dentists at the Advanced General Dentistry Clinic, Faculty of Dentistry, Mahidol University (Thailand) for all patients treated since 2016. Panoramic and periapical radiographs were taken before and after implant placement, to assess bone height around the implant. SDIs of 3 mm diameter and 10 mm length (PW plus®, PWSE, Nakhon Pathom, Thailand) were placed. After implantation for at least 2 months, corresponding housings were incorporated into overdentures using a conventional loading protocol. Assessment of implant survival rate, implant complications, and prosthetic maintenances were conducted as part of a regular implant checkup during the recall period from 2019–2020. Subsequently, patient characteristics, implant survival rate and complications, attachment complications, and prosthetic maintenance procedures were analyzed using descriptive statistics. Results Patients included in the study (n = 27) had a mean age of 68 years, and received 119 SDIs (41 in maxilla, 78 in mandible) and 38 overdentures (15 complete overdentures, 23 removable partial overdentures). The implant survival rate was 98.3% at mean survival time of 19.4 months (range, 6–55 months). After overdenture delivery, complications related to implant, attachments, and prosthetic maintenances were recorded. One implant complication (peri-implantitis) was recorded among 119 SDIs (0.8%). Attachment (Equator®) complications included: deformation of attachment matrices (34.4%), loss of attachment screw preload (14.0%), wear of metal housing (1.6%), wear of attachment head (0.8%), and dislodgement of attachment screw (0.8%). Prosthetic maintenance procedures comprised occlusal adjustment (72.7%), tissue surface adjustment (6.8%), denture base repair (6.8%), addition of artificial teeth (2.3%), and repair of artificial teeth (2.3%). Conclusion Our findings suggest that SDI retained overdenture is a successful treatment modality with a high implant survival rate (98.3%) over a 4.5 year follow-up period. Nevertheless, SDI retained overdenture maintenance is crucial.

Aim The present article reports clinical, radiographic, and histological healing of a case of alveolar ridge preservation treated with a cortical bone allograft and a bioabsorbable collagen wound dressing membrane for the reconstruction of a damaged extraction socket with a buccal bone dehiscence. Case report In the case reported, alveolar ridge preservation technique was applied in an extraction site with a buccal dehiscence type defect, using an allograft bone substitute and a bioabsorbable collagen wound dressing membrane followed by a successful implant placement at a later stage. Conclusion This case report showed that alveolar ridge preservation technique in a damaged socket with buccal dehiscence, using a freeze dried bone allograft covered with a fast resorption collagen membrane, can lead to new bone formation, of up to 53.53%, and ultimately allow safe implant placement.

Aim The present in vitro study evaluated the accuracy of intraoral scanners (IOS) in a completely edentulous arches and analyzed the influence of operator experience on accuracy, also time efficiency and operator’s difficulty perception related to IOS procedures. Materials and methods Twenty participants were enrolled for the digital scanning procedure of a maxillary edentulous metal model using an intraoral scanner, Aadva iOS100 (GC Corp., Tokyo, Japan). Participants were divided in two groups according to their experience in intraoral scanning procedures: Inexpert (InE group) without any experience in dental scanning (n=10) and Experts (E group) composed of operators with at least 3 year of scanning experience with IOS (n=5). Five IOS procedures were repeated for each operator and exported as a correspondent Stereolithography (STL) file. The same model was scanned with a laboratory scanner (LSS) (D1000 3 Shape Copenaghen Denmark), obtaining an STL file of the model which has been used as a reference. Accuracy of IOS were evaluated using a surface adaptation software (Geomagic Design X). The time required for each scanning procedure, and the perceived difficulty level were recorded for all the participants. The data obtained about accuracy, scanning time and difficulty perceived were compared between the two groups using the T-test for independent samples. The same variables were also correlated with each other using the Pearson’s coefficient. Results The highest trueness was observed for the scans provided by E participants. Precision ranged from 95,89 to 79,36 respectively in E and InE operators. For both trueness and precision there were significant differences between the two groups (p<0.05). Regarding scanning time, the more experienced operators were faster than inexpert ones with a significant difference (p<0.001). The two groups reported also differences in terms of difficulty perceived. Pearson’s correlation reported for time scanning a significant correlation with trueness p<0.001 and precision p<0.05 and between difficulty perceived and trueness p<0.05. Conclusions Digital impressions accuracy was different in E and InE operators as well as the scanning times, that was correlated with both trueness and precision.

Aim The purpose of this in vitro study was to evaluate the influence of the application of cyclic mechanical load on torque loss and on the seating installation of internal tapered abutments. Materials and methods Forty tapered implants and 40 abutments were used and divided into four groups (n=10): Group 1 (Titamax CM) and Group 2 (Strong SW Morse) received one-piece abutments; Group 3 (Titamax CM) and Group 4 (Strong SW Morse) received two-piece abutments. Tightening torque and reverse torque were applied, after 5 minutes, on all abutments. After that, tightening torque was applied to all the abutments, and were mechanically loaded and uninstalled. The two-piece abutments of Group 3 and Group 4 were divided in two subgroups (Subgroup 3a and Subgroup 4a: traction test required to remove the implant - pull out). The specimens were submitted to fatigue tests consisting of 1.200.000 cycles at a frequency of 2 Hz, dynamic compressive load of 50 N, and an angle of 30°. Data were analyzed through the normal distribution (Shapiro-Wilk, p> 0.05), followed by parametric statistical tests. Results After mechanical loading torque loss was higher in Group 4 (over 70% loss), followed by Group 1, Group 2 and Group 3 (over 50% loss). Group 1 and Group 2 presented no statistical difference. Subgroup 3a presented higher traction strength seating in post removal after mechanical loading (67.91 N), while Subgroup 4a presented only 1.92 N, it may present greater loosening of abutments. Conclusions The mechanical load significantly reduced the removal torque of the four groups of abutments tested, in addition to increasing frictional lock installation to the abutments of Subgroup 3a in the pull out test.