Finite Element Analysis to Study Stress Distribution on Distal Implants in All-On-Six Treatment Concepts as Affected Tilted and Short Implant.

The number of implants and their respective configurations for implant-supported treatment modalities have been studied for four implant-supported prostheses; however, it is not yet clear whether the use of tilting or short implants in rehabilitation would result in substantially improved bone/implant/prosthesis biomechanics in all-on-six concepts. This study compared the biomechanical behavior of tilted long implants and axially short implants to support fixed prostheses in an atrophic maxilla with all-on-six treatment concepts. Three different implant configurations were planned, and six models were obtained with posterior maxilla D3 and D4 bone densities in this study. Implants proper for the all on four concept were placed in all models. In Models 1 and 2, the short implant was placed; in Models 3 and 4, 30°, the mesial- angled implant was placed; and in Models 5 and 6, 45°, the mesial-angled implant was placed to the molar region. In the models created, 200 N vertical and 150 N oblique (45° angled bucco-palatal direction) forces were implemented to the bilateral tooth regions 4-5-6 on the rigid titanium-supported fixed hybrid prosthesis made on these models. When the stress values in the models were investigated, the oblique forces had higher stress values than the vertical forces. When the stresses created by oblique forces were assessed, the highest values were observed in the models created with short implants, and the lowest stress values were observed in the models made with 30°angle to mesial. When bone densities were assessed, more stress values were noted in models with D4 bone density. It has been shown that mesial tilted long implants placed in the posterior molar region, in addition to all four implant treatment concepts, create less stress against undesirable oblique forces compared to short implants.

Evaluation of two treatment concepts of four implants supporting fixed prosthesis in an atrophic maxilla: finite element analysis.

BACKGROUND: Currently, oblique placement of long implants or the use of short implants to circumvent the maxillary sinus area and provide support for fixed prostheses are viable alternatives. The purpose of this study was to compare these two treatment concepts and ascertain which one exhibits superior biomechanical characteristics. METHODS: Two different treatment concept models were constructed. The first one, LT4I, consisting of two mesial vertical implants positioned in lateral incisor regions and two distal tilted implants (45°) situated in second premolar regions of the maxilla. The second model, VS4I, includes two mesial vertical implants in lateral incisor regions and two vertically positioned short implants in second premolar regions. Numerical simulations were conducted under three loading types: firstly, oblique forces upon the molars; secondly, vertical forces upon the molars; thirdly, oblique forces upon the incisors. The maximum principal stress (σmax) and minimum principal stress (σmin) of the bone, as well as von Mises stress of the implants, were calcuated. RESULTS: Under oblique loading on the molar, higher stress values in the bone were observed in LT4I group. Under vertical loading on molar, higher stress values in the bone were also observed in LT4I group. Furthermore, little difference was found between the two groups under oblique loading on the incisor. CONCLUSION: Both treatment concepts can be applicable for edentulous individuals with moderate atrophic maxilla. Compared to tilted implants, short implants can transmit less occlusal force to the supporting tissues.

Clinical Assessment of Short (> 6 mm and ≤ 8.5 mm) Implants in Posterior Sites with an Average Follow-Up of 74 Months: A Retrospective Study.

PURPOSE: To evaluate the survival and success rates of short (> 6 mm and ≤ 8.5 mm) implants after at least 2 years of functional loading. Implants were assessed using clinical parameters such as marginal bone loss (MBL), pocket depth (PD), keratinized mucosa width (KMW), bleeding on probing (BoP), and the peri-implant condition (mucositis or peri-implantitis). Any correlations between clinical parameters were analyzed. MATERIALS AND METHODS: This observational and retrospective study included 114 posterior maxillary and mandibular implants placed in 27 women and 38 men with a mean age of 68.04 ± 9.07 years. Patients included in the study had received at least one short implant between 2001 and 2013, such that each implant was in occlusal function for at least 2 years by 2015. Patients with only long (≥ 10 mm) implants, patients with any systemic condition, and smokers were excluded from the study. PD, KMW, peri-implant condition, BoP, and MBL were the clinical parameters assessed in the study. Data on prosthesis type (single or splinted) and implant features were also obtained. All data were submitted to analysis via Mann-Whitney unpaired test, with a significance level of P < .05. Spearman correlation coefficient was also measured to verify the negative or positive correlation. RESULTS: The mean follow-up time was 74.08 months, and mean implant success and survival rates were 87.63% and 94.74%, respectively. There were 6 implant failures (5.26%). A total of 66 (59.46%) prostheses were screw-retained implant-supported restorations, and 45 (40.54%) were cemented. A total of 93 (86.49%) short implants were splinted to another implant, and 15 out of 111 (13.51%) restorations were single implants. Keratinized mucosa was missing around 43 (39%) implants, whereas PD was measured to be between 0 and 3 mm in 64.86% of implants and ≥ 4 mm in 31.53% of implants. MBL was ≤ 1.5 mm in 71.17% of cases and > two-thirds the length of the implant in 2.71% of cases. Mucositis and peri-implantitis were found in 22.52% and 7.21% of implants, respectively. The correlation coefficient showed a positive result for PD and MBL (0.11; P = .368) and negative results for PD and KMW (-0.42; P = .002) and KMW and MBL (-0.19; P = .183). CONCLUSIONS: Within the limitations of this study, it is possible to conclude that short implants are a feasible treatment option for dental rehabilitation. They are considered an excellent alternative to complex procedures and have high survival rates after at least 2 years of follow-up, with compatible peri-implant local tissue response. Moreover, a significant negative correlation between KMW and PD was observed.

Investigating the impact of diameters and thread designs on the Biomechanics of short implants placed in D4 bone: a 3D finite element analysis.

BACKGROUND: Dental implants emerge as a dependable and efficacious alternative for patients experiencing partial or complete tooth loss. The stability of these implants is influenced by surface topography and macro-level design. In cases where the height of the maxillary posterior region is diminished, employing short implants can prove advantageous. With the aim of examining the distribution of von Mises stress, strain, and micromovement in D4 bone quality surrounding platform-switched short implants, measuring 6 mm in length and featuring diameters ranging from 4 to 6 mm, as well as different thread designs, an in-depth finite element analysis was conducted under immediate loading conditions. METHODOLOGY: A 3D finite element model was constructed to simulate maxillary molar crowns, incorporating an implant with a length of 6 mm and varying diameters and thread designs. The diameters utilized were 4/3.6 mm, 5/4 mm, and 6/4.8 mm, while the thread designs included buttress, square, and triangle patterns. Each model underwent analysis with a 100 N force applied in two directions: vertical and oblique, relative to the long axis of the implant. Stress, strain, and micromovement in the peri-implant region were recorded, employing the Ansys Workbench R v.18.1 software for modelling and analysis. RESULTS: When comparing all three diameters, the wide diameter (6 mm threads) exhibited the lowest values of peri-implant von Mises stresses (3.3 MPa and 35.1 MPa), strains (194 Ɛ and 484 Ɛ), and micromovements (0.7 µm and 1.3 Ɛ) subjected to axial and non-axial loading of a 100 N force. Notably, square microthreads yielded the most favorable stress parameters among the different thread shapes, manifesting the minimum values of stress, strains, and micromovements in their vicinity. CONCLUSION: For the treatment of atrophic ridges or in scenarios necessitating extensive surgical preparation of the implant site, a combination of short implants, wide diameters, and platform switching can be employed. In situations with reduced bone height and the requirement for an implant-supported prosthesis to replace a missing permanent maxillary molar, the utilization of wide-diameter platform-switched short implants measuring 6 mm in length, featuring a square thread design, should be taken into consideration.

Effect of short implant crown-to-implant ratio on stress distribution in anisotropic bone with different osseointegration rates.

OBJECTIVE: This study aimed to provide evidence for the clinical application of single short implants by establishing an anisotropic, three-dimensional (3D) finite element mandible model and simulating the effect of crown-to-implant ratio (CIR) on biomechanics around short implants with different osseointegration rates. METHODS: Assuming that the bone is transversely isotropic by finite element method, we created four distinct models of implants for the mandibular first molar. Subsequently, axial and oblique forces were applied to the occlusal surface of these models. Ultimately, the Abaqus 2020 software was employed to compute various mechanical parameters, including the maximum von Mises stress, tensile stress, compressive stress, shear stress, displacement, and strains in the peri-implant bone tissue. RESULTS: Upon establishing consistent osseointegration rates, the distribution of stress exhibited similarities across models with varying CIRs when subjected to vertical loads. However, when exposed to inclined loads, the maximum von Mises stress within the cortical bone escalated as the CIR heightened. Among both loading scenarios, notable escalation in the maximum von Mises stress occurred in the model featuring a CIR of 2.5 and an osseointegration rate of 25%. Conversely, other models displayed comparable strength. Notably, stress and strain values uniformly increased with augmented osseointegration across all models. Furthermore, an increase in osseointegration rate correlated with reduced maximum displacement for both cortical bone and implants. CONCLUSIONS: After fixing osseointegration rates, the stress around shorter implants increased as the CIR increased under inclined loads. Thus, the effect of lateral forces should be considered when selecting shorter implants. Moreover, an implant failure risk was present in cases with a CIR ≥ 2.5 and low osseointegration rates. Additionally, the higher the osseointegration rate, the more readily the implant can achieve robust stability.

EXTRA-SHORT IMPLANTS MAY BE A VIABLE ALTERNATIVE TO LONGER IMPLANTS WITH BONE AUGMENTATION IN ATROPHIC MAXILLARY AND MANDIBULAR RIDGES.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Yu X, Xu R, Zhang Z, Yang Y, Deng F. A meta-analysis indicating extra-short implants (≤ 6 mm) as an alternative to longer implants (≥ 8 mm) with bone augmentation. Scientific reports. 2021 Apr 14;11(1):1-27. SOURCE OF FUNDING: The research was supported by the Science and Technology Major Project of Guangdong Province (2017B090912004). TYPE OF STUDY/DESIGN: Systematic review.

Implantes cortos y extracortos e inserción. Estudio retrospectivo con un seguimiento de 1 a 7 años / Short and extra-short implants in the maxilla and mandible with low insertion torque. Retrospective study with a follow-up of 1 to 7 years

Introducción: La realización de implantes cortos y extracortos en situaciones de extrema reabsorción maxilar y mandibular supone que la colocación del implante se realiza en condiciones de escaso volumen óseo residual y, por lo tanto. puedeser posible que el torque de inserción que se logre sea menor que en otras situaciones. En el presente artículo se investiga la posible relación que puede tener este bajo torque de inserción con la supervivencia del implante y la pérdida ósea crestal. Material y método: Fueron revisadas historias clínicas de forma retrospectivade los implantes insertados en el segundo semestre del año 2015 y primer trimestre del año 2021, para identificar implantes cortos y extracortos con torque de inserción < 20 N/cm. El implante fue la unidadde análisis para la estadística descriptiva en cuanto a la localización, dimensiones del implante, y mediciones radiográficas. El paciente fue la unidad de medida para el análisis de la edad, sexo y la historia médica. Las variables cualitativas se describieron mediante un análisis de frecuencias y las cuantitativas mediante media ydesviación estándar. La supervivencia de los implantes se calculó mediante el método de Kaplan-Meier.Resultados: Fueron reclutados 36 pacientes en los que se insertaron 40 implantes que cumplieron los criterios de inclusión marcados para el estudio. El torque de inserción de los implantes reclutados varió entre 5 y 15 Ncm, siendo 5 Ncm en el 37,5% de los casos, 10 Ncm en el 30% de los casos y 15 Ncm en el 32,5 % restante...(AU)

Introduction: The use of short, extrashort implants in situations of extrememaxillary and mandibular resorptionmeans that the implant is placed inconditions of low residual bone volumeand therefore it is possible that theinsertion torque achieved may be lowerthan in other situations. This article investigates the possible relationship thatthis low insertion torque may have with implant survival and crestal bone loss. Methods: Medical records of implants inserted in the second half of 2015 and first quarter of 2021 were retrospectively reviewed to identify short, extra-short implants with insertion torque < 20 N/cm.The implant was the unit of analysis for descriptive statistics in terms of location, implant dimensions, and radiographic measurements. The patient was the unit of measurement for the analysis ofage, sex and medical history. Qualitative variables were described by frequency analysis and quantitative variables by mean and standard deviation. Implant survival was calculated using the Kaplan Meier method. Results: Thirty-six patients were recruited and 40 implants were inserted that met the inclusion criteria for the study. The insertion torque of the recruited implants...(AU)

Interim rehabilitation of an edentulous situation with an overdenture retained by short implants during a staged vertical and horizontal ridge augmentation: a dental technique.

Interim rehabilitation of edentulous patients is essential in implant prosthodontics. However, surgical augmentation may be required for patients with reduced bone density, which complicates the use of an interim prosthesis. This report describes the rehabilitation of an edentulous patient with an interim maxillary overdenture retained by short implants with individual attachments during the healing period of vertical and horizontal ridge augmentation. This technique increased the stability of the interim prosthesis even with shortened flanges to eliminate any pressure on the surgical site. This technique could also be used when immediate loading is not possible due to lack of primary stability of the implants placed for definitive fixed prostheses.

Short Implants versus Standard Implants and Sinus Floor Elevation in Atrophic Posterior Maxilla: A Systematic Review and Meta-Analysis of Randomized Clinical Trials with ≥5 Years' Follow-Up.

Background and objectives: The aim of this systematic review with meta-analysis was to assess the performance of short implants in comparison with standard implants and sinus floor elevation in atrophic posterior maxilla. Materials and methods: The protocol of the study was registered in the PROSPERO database (CRD42022375320). An electronic search on three databases (PubMed, Scopus, Web of Science) was performed to find randomized clinical trials (RCTs) with ≥5 years' follow-up, published until December 2022. Risk of bias (ROB) was calculated using Cochrane ROB. A meta-analysis was performed for primary (implant survival rate, ISR) and secondary outcomes (marginal bone loss, MBL; biological and prosthetic complications). Results: Of 1619 articles, 5 RCTs met the inclusion criteria. The ISR showed a risk ratio (RR) of 0.97 [0.94, 1.00] (CI 95%), p = 0.07. The MBL indicated a WMD of -0.29 [-0.49, -0.09] (CI 95%), p = 0.005. Biological complications showed a RR of 0.46 [0.23, 0.91] (CI 95%), p = 0.03. Prosthetic complications showed a RR of 1.51 [0.64, 3.55] (CI 95%), p = 0.34. Conclusions: The available evidence suggests that short implants might be used as an alternative to standard implants and sinus floor elevation. After 5 years, in terms of ISR, standard implants and sinus floor elevation showed a higher survival rate comparted to short implants, although statistical significance was not achieved. Future RCTs with long-term follow-up are needed to draw a clear conclusion on the advantages of one method over another.

Clinical efficacy of extra-short implant (4 mm) placed in posterior areas: a Meta-analysis.

OBJECTIVES: This study aimed to systematically evaluate the safety and clinical efficacy of 4 mm-extra-short implant (ESI) placement in severely atrophic posterior areas. METHODS: Databases of PubMed, Embase, Cochrane Library, Web of Science, CNKI, and Wanfang from January 1, 2010, until August 31, 2022, were searched to identify randomized controlled trials or controlled clinical trials related to ESI and standard implants (SI). An additional hand search of the references of included articles was also conducted. Meta-analyses were carried out with RevMan 5.4 software. RESULTS: A total of 11 studies were included, involving six randomized controlled trials and five controlled clinical trials. The meta-analyses indicated that when implants were placed in the posterior area, the implant survival rate between ESI and SI did not significantly differ [RR=1.23, 95%CI (0.66, 2.27), P=0.52]. ESI resulted in significantly stable marginal bone level [MD=-0.16, 95%CI (-0.25,-0.07), P=0.000 7] and less biological complications [RR=0.34, 95%CI (0.19, 0.62), P=0.000 4] but more mechanical complications [RR=2.89, 95%CI (1.05, 7.92), P=0.04]. CONCLUSIONS: Based on the limited evidence, ESI could achieve clinical outcomes similar to those of SI when the height of the posterior alveolar bone is less than 5 mm, with lower technical sensitivity and fewer postoperative clinical complications than SI. Due to insufficient evidence and limited sample size, further clinical trials are needed to verify the long-term efficacy of ESI.

Short and Ultra-Short Implants, in Association with Simultaneous Internal Sinus Lift in the Atrophic Posterior Maxilla: A Five-Year Retrospective Study.

Recent short-term studies suggested the use of short and ultra-short implants in association with a modified osteotome sinus floor elevation (internal sinus lift) technique for the treatment of edentulous resorbed posterior maxilla. The aim of this retrospective study was to investigate this hypothesis in locking-taper implants with a mid-term follow-up of 5 years. Overall, 155 implants (32, 100, and 23 of, respectively, 5.0 mm, 6.0 mm, and 8.0 mm length) were positioned in the atrophic upper maxilla of 79 patients, and 151 implants were loaded with single crowns. Overall implant survival after 5 years was 94.84%. Implant survival for each length group was 93.75%, 94%, and 100% for 5.0, 6.0, and 8.0 mm length, respectively. Preoperative residual crestal bone height of 4.45 (1.3) mm increased to 9.25 (2.13) mm after implant placement and settled at 6.35 (1.73) mm after loading and at 5.25 (1.68) mm at follow-up. Elevation of the Schneiderian membrane was 4.8 (2.46) mm after implant placement, 3.06 (1.3) mm after loading, and 1.46 (1.06) mm at follow-up. Mean variations of peri-implant crestal bone loss and first bone-to-implant contact point were, respectively, -0.36 (1.3) mm and -0.62 (1.15) mm. It can be confirmed that internal sinus lift procedure revealed stable bone gain and negligible resorption at mid-term follow-up for atrophic upper crests with reduced height.

Implantes de 4, 5 y 5, 5 mm longitud insertados de forma directa en elevación crestal con hueso autólogo unido al endoret-prgf en alturas óseas residuales de 2-3 mm: estudio retrospectivo / 4.5 and 5.5 mm implants directly inserted in crestal elevation with autologous bone added to endoret-prgf in 2-3 mm residual bone heights: retrospective study

Introducción. El abordaje del maxilar atrófico en altura es un reto para el odontólogo, presentándose cada vez más habitualmente nuevas técnicas que nos permiten la colocación de implantes con menor invasividad para el paciente. La incorporación del abordaje transcrestal y la disminución de la longitud de los implantes han sido clave para llegar al tratamiento de más pacientes con un menor número de intervenciones quirúrgicas. En el presente estudio se muestran una serie de casos con extrema atrofia ósea en altura rehabilitados mediante elevación transcrestal e implantes de 4,5 y 5,5 mm de longitud. Material y método. Se ha realizado un estudio retrospectivo en pacientes en los que se insertaran implantes extracortos (4,5 y 5,5 mm longitud) de forma directa Mediante elevación transcrestal con alturas de cresta residual entre 2 y 3 mm. El implante fue la unidad de análisis para la estadística descriptiva en cuanto a la localización, dimensiones del implante, y mediciones radiográficas. El paciente fue la unidad de medida para el análisis de la edad, sexo y la historia médica. La variable principal fue la ganancia en altura sobre el ápice del implante tras 6 meses de la cirugía y un año después de la carga comparándose las dos mediciones y como variables secundarias se registraron las complicaciones biológicas y el fracaso del implante.Resultados. Fueron reclutados diez pacientes que cumplieron los criterios de inclusión, en los que fueron insertados 20 implantes. La altura media del volumen óseo residual fue de 3,1 mm (+/- 0,3 mm con un rango de 3-4 mm). En todos los casos se realizó una elevación de seno transcrestal, con hueso autólogo particulado obtenido del fresado de la zona de generación del neoalveolo para la inserción del implante, siendo la media de elevación sobre el ápice del implante en milímetros de 2,8 mm (+/- 0,99 rango 1,9 -5 mm). En el Cone-beam de control al año de carga de los implantes estudiados, e mantiene la ganancia ósea lograda (AU)

Introduction. The approach to the atrophic maxilla in height is a challenge for the dentist, and new techniques that allow us to place implants with less invasiveness for the patient are becoming more and more common. The incorporation of the transcrestal approach and the reduction in implant length have been key to treating more patients with a smaller number of surgical interventions. In this study we present a series of cases with extreme bone atrophy in height rehabilitated using transcrestal elevation and 4.5 and 5.5 mm long implants.Methods. A retrospective study was carried out in patients in whom extra-short implants (4.5 and 5.5 mm in length) were inserted directly by transcrestal elevation with residual ridge heights between 2 and 3 mm. The implant was the unit of analysis for descriptive statistics in terms of location, implant dimensions, and radiographic measurements. The patient was the unit of measurement for the analysis of age, sex and medical history. The primary variable was the gain in height above the implant apex 6 months after surgery and one year after loading, comparing the two measurements. Biological complications and implant failure were recorded as secondary variables. Results. Ten patients who met the inclusion criteria were recruited and 20 implants were inserted. The mean residual bone volume height was 3.1 mm (+/- 0.3 mm with a range of 3-4 mm). In all cases a transcrestal sinus lift was performed, with autologous particulate bone obtained from the drilling of the neoalveolus generation zone for implant insertion, the mean of this elevation above the implant apex in millimetres being 2.8 mm (+/- 0.99 range 1.9 -5 mm). In the control TC at one year of loading of the implants studied, the bone gain achieved was maintained (AU)

Effect of Photobiomodulation Therapy on Peri-Implant Bone Healing in Extra-Short Implants in a Rabbit Model: A Pilot Study.

Objective: To evaluate the effects of photobiomodulation therapy (PBMT) at distinct energy levels on peri-implant bone healing in extra-short implants in a experimental rabbit model. Background: The effect of PBMT on peri-implant bone healing in short implants remains unclear. This explored the effect of PBMT on extra-short implants in terms of bone-implant contact (BIC) length and rate, and implant stability quotient (ISQ). Methods: Fifteen white New Zealand rabbits were randomly divided into five groups. In all groups, extra-short implants (3.5 × 4 mm; Nucleoss T6, Izmir/Turkey) were placed in both tibias of the rabbits. PBMT was performed in four groups (group 1, 5 J/cm2; group 2, 10 J/cm2; group 3, 20 J/cm2; and group 4, 25 J/cm2); no PBMT was performed in the control group. On the 30th day, the rabbits were sacrificed and peri-implant tissue samples were obtained to determine the BIC length and BIC rate. Implant stability levels were measured by resonance frequency analysis using the Osstell penguin device and were determined as ISQ values on the 1st and 30th days of the study. Results: PBMT significantly increased the BIC length and BIC rate in groups 3 and 4 (p < 0.001). For the ISQ values, there were significant differences between the 1st and 30th day (p < 0.001). On the 30th day, the ISQ values were significantly higher in groups 3 and 4 compared with the remaining groups (p < 0.001). Conclusions: In this study, PBMT improved peri-implant bone healing through increase in BIC length, BIC rate, and ISQ parameter values in extra-short implants.

A prospective, multicentre study of 6-mm short implants in posterior alveolar bone supporting splinted crowns: A 5-year follow-up study.

AIM: To evaluate the clinical and radiographic outcomes of 6-mm short implants, placed in the posterior jaws and supporting splinted crowns, at 5 years after early loading. MATERIALS AND METHODS: Forty-five patients with 95 implants (diameter: 4 mm; length: 6 mm) were enrolled at three centres. Two to three implants were placed in either the maxillary or the mandibular posterior region in each patient and restored with screw-retained splinted crowns at 6 weeks later. Clinical and radiographic outcomes were evaluated at implant placement, at loading, and at 6, 12, 24, 36, and 60 months after loading. Biological and mechanical complications were recorded. Marginal changes in bone level in relation to clinical parameters were evaluated using a generalized linear mixed model. RESULTS: During the 5 years of follow-up, the mean change in the marginal bone level (MBL) was 0.04 ± 0.14 mm. Four implants in four patients were lost before loading, one implant in one patient was lost at the 5-year follow-up, and two patients were lost to follow-up. The survival and success rates were 88.4% (38/43) at the patient level. The incidence rates of peri-implant mucositis and peri-implantitis were 29.4% and 7.0%, respectively. The rate of technical complications was 14.0%. CONCLUSIONS: Over a 5-year period, 6-mm short implants supporting early loaded splinted crowns in maxillary or mandibular posterior regions showed stable MBLs and acceptable technical and biological complication rates.

Three-year observations on the effect of different cusp inclinations on the restoration of short maxillary first molar implants: A randomized controlled trial.

Objective: To investigate the effect of different cusp inclination on short implant prosthesis of maxillary first molar after 3 years of weight-bearing in biology and mechanics. Methods: The clinical patients were randomly selected from the database and divided into four groups A, B, C, and D according to the cusp inclination of the maxillary first molar short implant restoration (4.8 mm × 8 mm, Dentium). 20 cases in each group. The cusp inclination was 10 degrees-15 degrees, 15 degrees-20 degrees, 20 degrees-25 degrees, 25 degrees-30 degrees. After 3 years of weight-bearing, cone beam computed tomography (CBCT) and Florida probe were used to measure and observe the height of alveolar bone (H), periodontal probing depth (PD) and modified sulcus bleeding index (MBI). Visual analogue scale (VAS) was used to evaluate the overall satisfaction of patients, and the mechanical complications of each group within 3 years of implant weight-bearing were counted. Results: The H and PD of group D were 1.09 ± 0.23 and 2.19 ± 0.11 respectively, which were significantly higher than those of group A, B and C (p < 0.05). There was no significant difference in MBI between groups A-D (p > 0.05). The VAS scores of group B and group C were 88.36 ± 5.12 and 88.70 ± 4.52 respectively, which were higher than those of group A and group D (p < 0.05). The incidence of food impaction, porcelain collapse and abutment loosening in group D were 40.0%, 25.0% and 15.0% respectively, which were higher than those in group B and C (p < 0.05). Conclusion: The risk of biological and mechanical complications increases after long-term weight-bearing of maxillary first molar short implant prostheses with high cusp inclination. The cusp inclination of short implant prostheses should be designed as low as 25 degrees.

Displacement of the full body of a dental implant into the sinus space without membrane perforation and subsequent osseointegration: a case report.

An increasing number of studies have investigated the use of osteotome sinus floor elevation (OSFE) with simultaneous implant placement for maxillary sinus floor residual bone height (RBH) <4 mm. Many studies have reported good clinical results, but very few have reported complications related to this procedure. Here, the case of a 50-year-old female patient with an RBH in the left upper posterior region of 1-4 mm, who underwent OSFE with simultaneous placement of three Bicon short® implants, is described. One of the implants was found to be displaced during the second-stage surgery. The displaced implant was removed using piezosurgery, OSFE with simultaneous implant placement was repeated, and the missing tooth was reconstructed 6 months later. This case suggests that OSFE with simultaneous implant placement is feasible for severely atrophic maxillary sinus floor, but carries a risk of implant displacement.

The Effect of Implant Length and Diameter on Stress Distribution around Single Implant Placement in 3D Posterior Mandibular FE Model Directly Constructed Form In Vivo CT.

A three-dimensional (3D) finite element (FE) model of the mandibular bone was created from 3D X-ray CT scan images of a live human subject. Simulating the clinical situation of implant therapy at the mandibular first molar, virtual extraction of the tooth was performed at the 3D FE mandibular model, and 12 different implant diameters and lengths were virtually inserted in order to carry out a mechanical analysis. (1) High stress concentration was found at the surfaces of the buccal and lingual peri-implant bone adjacent to the sides of the neck in all the implants. (2) The greatest stress value was approximately 6.0 MPa with implant diameter of 3.8 mm, approx. 4.5 MPa with implant diameter of 4.3 mm, and approx. 3.2 MPa with implant diameter of 6.0 mm. (3) The stress on the peri-implant bone was found to decrease with increasing length and mainly in diameter of the implant.

Short strategic implants for mandibular removable partial dentures: One-year results from a pilot randomized crossover abutment type study.

OBJECTIVES: The present pilot study analyzed two abutment types (a retentive ball and a non-retentive dome) in implant-assisted removable partial dentures (IARPDs) on 6 mm short implants with respect to clinical, radiological, and patient-reported outcomes (PROs), during the first year. MATERIALS AND METHODS: Two implants were placed bilaterally in mandibular molar sites, converting existing free-end removable partial dentures (RPDs) to IARPDs. Twelve subjects were randomized to initially receive either the dome (Group A, n = 6) or the ball abutment (Group B, n = 6). After eight weeks, the abutments were exchanged. After another 8 weeks, the participants were given the choice of one of the abutments. Mean values and standard deviations (SD) were calculated, and random-effect linear regression analyses were applied to analyze marginal bone level alterations and PROs (α < .05). RESULTS: Twelve participants were included in the study; however, one dropout occurred. Patient ratings increased significantly in both study groups. The majority of the participants (82%) ultimately chose the ball abutment. The implant survival rate was 100%, and the success rate was 90.9% twelve months after implant placement (mean peri-implant bone-loss: -1.2; SD: 0.6 mm) without a statistically significant difference between the study groups, in terms of clinical- and radiological outcomes. CONCLUSION: Placing 6 mm short implants at mandibular molar sites of RPD wearers seems to be a viable treatment option, based on this investigation with a short-term follow-up. Although only minor differences between the two abutments were observed, patients seem to prefer the ball over the dome abutment.

Immediate Post-Extraction Short Implant Placement with Immediate Loading and without Extraction of an Impacted Maxillary Canine: Two Case Reports.

For the treatment of impacted maxillary canines, traction associated with a complete orthodontic treatment is the first choice in young patients. However, in adults, this treatment has a worse prognosis. The surgical extraction of the impacted tooth can result in a series of complications and a compromised alveolar bone integrity, which may lead to the requirement of a bone regeneration/grafting procedure to replace the canine with a dental implant. These case reports aimed to describe an alternative treatment procedure to the surgical extraction of impacted maxillary canines in adults. Following clinical and computerized tomography-scan (CT-Scan) examination, the possibility of maintaining the impacted canine in its position and replacing the temporary canine present in its place with a dental implant was planned. A short dental implant with an immediate provisional crown was placed, without contacting the impacted canine. At 3 months follow-up, a definitive metal-ceramic restoration was placed. Follow-up visits were performed periodically. The implant site showed a physiological soft tissue color and firmness, no marginal bone loss, no infection or inflammation, and an adequate aesthetic result in all follow-up visits. These results suggest that the treatment carried out is a valid option to rehabilitate with an osseointegrated short implant area where a canine is included, as long as there is a sufficient amount of the remaining bone.

Ultra-short versus standard-length dental implants in conjunction with osteotome-mediated sinus floor elevation: A randomized controlled clinical trial.

BACKGROUND: The ability to restore missing teeth with dental implants is dictated by the available bone and by the presence of anatomical structures. The potential to insert ultrashort implants avoids additional surgical procedures and its inherent complications. The last European Association of Dental Implantologists consensus in 2016 defined ultrashort implants and standard-length dental implants as <6 and >8 mm, respectively. PURPOSE: The present study aimed to investigate whether single standing ultrashort dental implants (US) could provide a viable therapeutic alternative to osteotome mediated sinus floor elevation in combination with standard-length dental implants (SL) 10 mm in posterior maxillary rehabilitation with reduced bone height. MATERIALS AND METHODS: The study was conducted as a prospective parallel group controlled clinical trial with a 12 month follow-up, where 48 implants were randomized into two groups; US-group (5.5 mm) and SL-group (10 mm) implants placed with osteotome-mediated sinus floor elevation. Crestal bone loss (CBL) was defined as the study's primary outcome, while implant survival, buccal bone thickness, implant stability, probing depth, gingival recession, and adverse effects were assessed as secondary outcomes. RESULTS: Mesial CBL was 1.13 ± 0.52 mm in SL- and 0.72 ± 0.52 mm in US-group (P = .021), while distal CBL was 1.44 ± 0.72 mm in SL- and 0.91 ± 0.69 mm in US-group at 12 months (P = .0179). Regarding implant stability, probing depth, and gingival recession there was no statistically significant difference between the two groups. Regarding implants' survival, three implants were lost in the US-while only one implant was lost in the SL-group (P = .6085; Fisher's exact test). Nevertheless, the ultrashort implants were associated with a tripling of the failure rate and uncertainty where the true failure rate is uncertain (relative risk 3.0; confidence interval 0.3-26.8). CONCLUSIONS: Within the current trial's limitations, US-appear appear promising as they are associated less postoperative discomfort, minimal invasiveness and less CBL. However, larger sample size is required to determine whether the ultrashort have an acceptable survival rate.