RESUMEN
This in vitro study was conducted to investigate the repeatability of the implant stability quotients (ISQ) measured with multipegs after numerous sterilizations and to detect the exact time when the readings start to deviate. Multipegs were sterilized with 3 different methods (autoclaved, autoclaved + ultrasonic cleaner, chemical disinfection + autoclaved) and grouped according to the method applied. All specimens were put into the autoclave with sealed packages every time they were sterilized. Each specimen was sterilized 50 times according to the technique described in its group after an ISQ measurement was performed. Results of the 2-way analysis of variance showed that neither the sterilization method nor the cycles, nor their interaction, were statistically significant. A multipeg may be reused multiple times after sterilization procedures and may be more cost-effective than a disposable smartpeg for checking implant stability after confirming these results in further investigations.
Asunto(s)
Implantes Dentales , Titanio , Análisis de Frecuencia de Resonancia , Esterilización , UltrasonidoRESUMEN
The objective was to evaluate the influence of residual bone height (RBH) and implant macro-design on the primary stability (PS) of implants using a simultaneous sinus floor elevation (SFE) and implant insertion model. Fresh bovine rib samples that resembled type-IV density that were confirmed by computerized tomography were prepared to represent 4 groups of varying RBHs (3, 6, 9, 15 mm). To simulate simultaneous implant insertion with SFE, 120 implants in different macro-designs (group R: NobelReplace; group P: NobelParallel; group A: NobelActive, Nobel Biocare, Gothenburg, Sweden) were randomly inserted at RBHs of 3, 6, 9, and 15 mm in each rib. The implant stability quotient (ISQ) was measured immediately after implant insertion. RBH and implant macro-design have an impact on ISQ values (P < .001). ISQ values were the highest with RBH of 15 mm, followed by RBHs of 9, 6, and 3 mm. (P < .001). There was no statistically significant difference between different implant macro-designs at RBHs of 3 and 15 mm regarding ISQ values (P = .111, P = .551). ISQ values of group P were higher than those of group R and group A at an RBH of 6 mm (P = .049, P = .029). ISQ values were also higher in group P compared to group A at an RBH of 9 mm (P = .006). A higher PS may be expected in sites with higher RBH, regardless of the macro-design. In addition, cylindric implant design may enhance the PS at RBHs of 6 and 9 mm in simultaneous implant insertion with SFE.
Asunto(s)
Implantes Dentales , Elevación del Piso del Seno Maxilar , Animales , Bovinos , Implantación Dental Endoósea/métodos , Elevación del Piso del Seno Maxilar/métodos , Seno Maxilar/cirugía , Tomografía Computarizada por Rayos XRESUMEN
This technique article describes an efficient, cost effective and time saving procedure using the fractured abutment as a custom cast post and core when an overdenture abutment is fractured and attempts to retrieve the fractured segment fail.
Asunto(s)
Diseño de Implante Dental-Pilar , Implantes Dentales , Pilares Dentales , Prótesis Dental de Soporte Implantado , Prótesis de RecubrimientoRESUMEN
STATEMENT OF PROBLEM: Digital scanning systems have become popular, but whether these systems are adequate for complete-arch implant-supported fixed dental prostheses is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the trueness of 10 different dental intraoral scanners. MATERIAL AND METHODS: Six implant analogs were installed, and an edentulous mandibular model composed of scannable Type 4 gypsum was scanned with 10 different intraoral scanners (3D Progress, Omnicam, Bluecam, Apollo DI, Planscan, E4D Tech, TRIOS MonoColor Cart, TRIOS Color Cart, TRIOS Color Pod, Lythos), 10 times each after the scan body was placed on the implant abutments. The data obtained were then converted into standard tessellation language format. For the control group, the gypsum model was scanned with an industrial scanner (ATOS Core 80). For trueness, the dental and industrial scanning data packs were analyzed with 3D comparison software. Statistical analyses were performed by using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: When ranked according to their surface superimposition values, the Color POD, Omnicam, Apollo DI, Color Cart, MonoColor Cart, and Bluecam scanners were found within the range of 31 to 45 µm. This group was followed by E4D, 3D Progress, Lythos, and Planscan, which were found within the range of 82 to 344 µm according to the same criteria. CONCLUSIONS: Some of the digital scanners had the necessary performance for the fabrication of complete-arch implant-supported fixed dental prostheses. However, the possibility of data loss producing artifacts should be considered.
Asunto(s)
Implantes Dentales , Técnica de Impresión Dental , Diseño Asistido por Computadora , Arco Dental/diagnóstico por imagen , Imagenología Tridimensional , Modelos DentalesRESUMEN
The establishment of dental implant stability is mandatory for successful osseointegration. Resonance frequency analysis (RFA) is the most frequently used method for the clinical measurement of implant stability. The purpose of the present study was to evaluate the reliability of the recently developed RF analyzer Penguin RFA and to compare it with the traditional RF analyzer Osstell ISQ. Sixty implants were inserted into fresh steer vertebrae and pelvis. Implant stability was measured using Penguin RFA by its transducers (multipegs) and Osstell ISQ by its transducers (smartpegs). Additionally, stability was measured by multipegs with Osstell ISQ and by smartpegs with Penguin RFA. The intraobserver and interobserver reliability of Penguin RFA were estimated by the intraclass coefficient (ICC). Mean implant stability quotients (ISQs) measured with Osstell ISQ were higher than the ISQs measured with Penguin RFA (P < .05). The intra- and interobserver reliability of Penguin RFA were considered as excellent (ICC > 0.7). For Osstell ISQ, no significance in ISQs was detected between the readings by smartpegs and multipegs (P > .05), while for Penguin RFA ISQs by smartpegs were significantly higher than the ISQs by multipegs (P <.05). The recently developed Penguin RFA is reliable and can be used in clinical practice for the measurement of dental implant stability regardless of the bone type. The multipegs originally manufactured for the Penguin RFA is also compatible with Osstell ISQ.
Asunto(s)
Implantes Dentales , Retención de Prótesis Dentales , Implantación Dental Endoósea , Espectroscopía de Resonancia Magnética , Oseointegración , Reproducibilidad de los Resultados , Titanio , VibraciónRESUMEN
The design of an implant has a great effect on primary stability. The purpose of this study was to determine the differences in primary stability between straight and tapered Neoss ProActive implants in type I and type III bones using resonance frequency analysis (RFA) and electronic percussive testing (EPT) methods. Fresh cow vertebrae and pelvis were used as models of type III and type i bone, respectively. Implants of 2 different designs-straight and tapered Neoss ProActive implants with a thread cutting and forming (TCF) design, both 3.5-mm wide and 11-mm long-were placed in both types of bone (n = 60). The primary stability of all implants was measured by an experienced clinician blinded to the study protocol using the EPT and RFA devices. No statistically significant difference was found between the implant stability quotients and the percussive test values of straight and tapered implants in either bone type. Within the limitations of this ex vivo study, it may be concluded that the shape of an implant with a TCF design does not affect primary stability.
Asunto(s)
Implantes Dentales , Diseño de Prótesis Dental , Retención de Prótesis Dentales , Animales , Huesos , Bovinos , Implantación Dental Endoósea , Femenino , Análisis de Frecuencia de ResonanciaRESUMEN
This clinical report describes prosthetic rehabilitation applied to an edentulous patient with microstomia. Intraoral scanning was used for preliminary impressions, edentulous models were printed using a 3D printer, custom 2-piece impression trays for definitive impressions were made, and a 2-piece collapsible maxillary and a conventional mandibular denture were fabricated. Intraoral scanning is a useful alternative to conventional impression techniques and can be used safely in patients with microstomia for preliminary impressions.
Asunto(s)
Microstomía , Boca Edéntula , Técnica de Impresión Dental , Diseño de Dentadura , Humanos , MandíbulaRESUMEN
ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Effects of modified abutment characteristics on peri-implant soft tissue health: a systematic review and meta-analysis. Sanz-Martín I, Sanz-Sánchez I, Carrillo de Albornoz A, Figuero E, Sanz M. Clin Oral Implants Res 2018; 29(1):118-29. SOURCE OF FUNDING: Nonprofit foundation: Oral Reconstruction Foundation, Basel, Switzerland. TYPE OF STUDY/DESIGN: Systematic review with meta-analysis of data.
Asunto(s)
Implantes Dentales , Titanio , Pilares Dentales , Humanos , CirconioRESUMEN
OBJECTIVES: The aim of this study was to determine the influence of different frontal bone defect localizations on primary stability values of 2 different implant designs. MATERIALS AND METHODS: Eight cow rib segments were prepared before implant installation, as 2 segments with coronal, 2 with middle, and 2 with apical defects and 2 with control. Thirty-two cylindrical and 32 tapered implants were placed in the remaining 4 segments. Implant stability measurements were performed using electronic percussive testing and resonance frequency analysis. RESULTS: No significance was detected between the stability values of the 2 implant designs except the implant stability quotient (ISQ) of control groups. The tapered implants control group showed significantly higher lateral ISQs compared with cylindrical implants (P = 0.033). For both implant types, stability values were significantly lower in coronal defects (P < 0.01). No significant differences were detected in other defect types. CONCLUSION: Within the limitations of this study, it may be concluded that coronal defects may influence primary stability negatively, compared with middle and apical defects. Although statistically not significant, coronal defects caused lower primary stability values with the tapered design compared with parallel design.
Asunto(s)
Interfase Hueso-Implante/patología , Implantes Dentales , Diseño de Prótesis Dental , Hueso Frontal/cirugía , Animales , Bovinos , Diseño de Prótesis Dental/métodos , Retención de Prótesis Dentales , Análisis del Estrés Dental/métodos , Hueso Frontal/patología , Técnicas In Vitro , Costillas/cirugíaRESUMEN
PURPOSE: To analyze the prognostic factors that are associated with the success, survival, and failure rates of dental implants. MATERIAL AND METHODS: Data including implant sizes, insertion time, implant location, and prosthetic treatment of 1656 implants have been collected, and the association of these factors with success, survival, and failure of implants was analyzed. RESULTS: The success rate was lower for short and maxillary implants. The failure rate of maxillary implants exceeded that of mandibular implants, and the failure rate of implants that were placed in the maxillary anterior region was significantly higher than other regions. The failure rates of implants that were placed 5 years ago or more were higher than those that were placed later. CONCLUSIONS: Anterior maxilla is more critical for implant loss than other sites. Implants in the anterior mandible show better success compared with other locations, and longer implants show better success rates. The learning curve of the clinician influences survival and success rates of dental implants.
Asunto(s)
Implantes Dentales , Retención de Prótesis Dentales/estadística & datos numéricos , Fracaso de la Restauración Dental/estadística & datos numéricos , Implantación Dental/efectos adversos , Implantación Dental/métodos , Implantación Dental/estadística & datos numéricos , Implantes Dentales/efectos adversos , Implantes Dentales/normas , Implantes Dentales/estadística & datos numéricos , Femenino , Humanos , Masculino , Mandíbula , Maxilar , Persona de Mediana Edad , Pronóstico , Estudios Retrospectivos , Factores de RiesgoRESUMEN
OBJECTIVE: This study investigated the possible detrimental effects of steam treatment on the surface of type III dental stone, which is a common laboratory material used for the construction of removable dentures. MATERIAL AND METHODS: Forty dental stone specimens were prepared and divided into four groups (A, B, C and D), and group A was used as the control group. The other groups were treated with steam from a standard distance for varying durations (30, 60 and 120 s). RESULTS: The duration of steam cleaning significantly increased Ra values (F = 63.150, p = 0.000). Similarly, the duration of steam application was directly correlated with the weight changes (F = 17.721, p = 0.000). A significant amount of dental stone can be removed from the surface while treating with steam. CONCLUSION: These studies demonstrated that expanded periods of steam cleaning cause weight loss and abrade the surface of type III dental stones; therefore, these devices should be used with caution during denture fabrication procedures.
Asunto(s)
Sulfato de Calcio/química , Materiales Dentales/química , Diseño de Dentadura , Dentadura Completa , Dentadura Parcial Removible , Vapor , Tensoactivos/química , Desecación , Humanos , Ensayo de Materiales , Propiedades de Superficie , Temperatura , Factores de TiempoRESUMEN
The prosthetic treatment of patients with an edentulous maxilla opposing mandibular natural teeth is one of the most challenging endeavors that face clinicians. Occlusal forces from the opposing natural teeth may cause fractures in the maxillary prosthesis and also result in advanced bone loss of the edentulous maxilla. With the presence of extreme gagging reflex, the treatment may become more complicated. This article describes and illustrates the 2-stage surgical and prosthetic treatment of a patient with an edentulous maxilla opposing natural teeth. In the beginning, the patient was treated with 4 implants and a maxillary implant-supported overdenture. The extreme gagging reflex and the occlusal forces from the mandibular natural teeth obligated the team a second stage surgical and prosthetic treatment, which included increasing the number of implants after bilateral sinus lifting in the posterior maxilla and fabricating a maxillary fixed hybrid prosthesis made of micro-ceramic composite that yielded a satisfactory result.
Asunto(s)
Diseño de Prótesis Dental , Prótesis Dental de Soporte Implantado , Dentadura Completa Superior , Arcada Edéntula/rehabilitación , Elevación del Piso del Seno Maxilar , Implantes Dentales , Porcelana Dental , Fracaso de la Restauración Dental , Atragantamiento , Humanos , Arcada Edéntula/cirugía , Masculino , Maxilar/cirugía , Persona de Mediana Edad , ReoperaciónRESUMEN
Titanium and its alloys have been widely used for dental prosthetic devices because of their superior mechanical properties and biocompatibility. However, the incidence of titanium hypersensitivity or allergy is still unknown and the discussion about its existence is ongoing. Unexplained implant failures have also forced dental clinicians to investigate the possibility of titanium hypersensitivity or allergy. This review focuses on the potential of dental implant-related titanium hypersensitivity or allergic reactions. It includes an examination of the existing scientific literature and current knowledge. Evidence-based data and studies related to titanium hypersensitivity in dental implant patients are also discussed.
Asunto(s)
Implantes Dentales/efectos adversos , Materiales Dentales/efectos adversos , Hipersensibilidad/etiología , Titanio/efectos adversos , Materiales Biocompatibles/efectos adversos , Aleaciones Dentales/efectos adversos , Fracaso de la Restauración Dental , Humanos , Hipersensibilidad/inmunología , Titanio/inmunologíaRESUMEN
PURPOSE: Τo evaluate and compare the marginal bone loss (MBL), survival rates, and periodontal parameters of immediately loaded implants with either Dolder bar or Locator attachments placed in the interforaminal region of edentulous mandibles. MATERIALS AND METHODS: A total of included 19 patients with edentulous mandibles each received two implants in the interforaminal area of the symphysis. Randomly allocated Dolder bar or Locator attachments were then attached immediately, and both clips and a framework were fastened to the denture by the dental laboratory within 24 hours. RESULTS: A total of 28 subjects with 56 implants were treated in accordance with the immediate-loading study protocol. Of these, 9 patients were lost to follow-up; 1 patient reported a serious illness and 8 patients moved and couldn't be reached. The 19 subjects not lost to follow-up (11 women and 8 men; average age: 68 years) were included. Every patient received either two Locator abutments and were assigned to group A (7 patients; 36.8%) or two multiunit abutments and were assigned to group B (12 patients; 63.2%). No implant failure was detected for either group, and therefore the survival rate for both groups was 100% after 5 years. After 5 years without any symptoms, 2 implants from group A and 7 implants from group B showed > 2 mm of MBL, which makes the group A success rate 85.7% and the group B success rate 70.8%. Modified sulcular bleeding index (mSBI) did not differ significantly at any of the measurement intervals. However, the modified plaque index (mPI) of group B was significantly higher than group A at the 60-month follow-up. CONCLUSION: It can be concluded that either splinting or not splinting the immediately loaded interforaminal implants to retain mandibular overdentures (OVDs) does not affect marginal bone levels after 5 years and immediate loading of nonsplinted implants with Locator attachments can be safely preferred to retain mandibular OVDs.
Asunto(s)
Pérdida de Hueso Alveolar , Implantes Dentales , Carga Inmediata del Implante Dental , Arcada Edéntula , Masculino , Humanos , Femenino , Anciano , Tasa de Supervivencia , Carga Inmediata del Implante Dental/métodos , Prótesis de Recubrimiento , Arcada Edéntula/cirugía , Prótesis Dental de Soporte Implantado , Mandíbula/cirugía , Resultado del Tratamiento , Retención de DentaduraRESUMEN
OBJECTIVE: The aim of this study was to compare the quality of life and patient satisfaction outcomes of two attachment systems in mandibular overdentures with different numbers of supporting implants. MATERIALS AND METHODS: Sixty-two edentulous patients with either splinted or single attachments in mandibular implant overdentures with different numbers of supporting interforaminal implants were investigated for patient satisfaction and quality of life in this retrospective study. Comparisons between groups were perceived by the Mann-Whitney U test. Relations among the parameters were investigated by Spearman's rho correlation analysis. The results were evaluated statistically at a significance level of p < 0.05. RESULTS: No statistically significant association is found between visual analogue scales scores and attachment type as well as implant number (p > 0.05), whereas Oral Health Impact Profile (OHIP)-14 total scores for patients with 4-implant-supported bars were significantly lower than all the other attachment types (p < 0.05). Additionally, a negative (rate = 32.2%), statistically significant association between period of edentulism and total OHIP-14 scores was detected (p < 0.05). CONCLUSIONS: A mandibular implant-retained overdenture supported with four implants and bar attachments shows the highest 'quality of life' score and patient satisfaction is not influenced by the number of implants or attachment type.
Asunto(s)
Implantes Dentales , Prótesis Dental de Soporte Implantado/psicología , Retención de Dentadura/instrumentación , Prótesis de Recubrimiento/psicología , Satisfacción del Paciente , Calidad de Vida , Adaptación Fisiológica/fisiología , Anciano , Anciano de 80 o más Años , Pilares Dentales , Implantes Dentales/psicología , Oclusión Dental , Bases para Dentadura , Diseño de Dentadura , Rebasado de Dentaduras , Dentadura Completa Inferior/psicología , Estética Dental , Femenino , Estudios de Seguimiento , Humanos , Arcada Edéntula/rehabilitación , Masculino , Masticación/fisiología , Persona de Mediana Edad , Higiene Bucal , Dimensión del Dolor , Estudios Retrospectivos , Habla/fisiología , Resultado del TratamientoRESUMEN
AIM: Assessment of the influence of such factors as attachment type, number of implants, gender and age of patients on maximum bite force (MBF). MATERIAL AND METHODS: Sixty-two edentulous patients (32 females, 30 males; aged 64.03 ± 10.07 years, range 42-90 years) with mandibular implant overdentures with various attachment types were included in the study and their MBFs were recorded. The results were evaluated statistically at a significance level of p < 0.05. RESULTS: The MBF in male patients was found to be statistically significantly (p < 0.05) higher than in female patients. No statistically significant differences (p > 0.05) were found with respect to age groups, attachment types and number of implants supporting the mandibular overdentures. CONCLUSION: Within the limitations of this study, it is concluded that independent of the number applied, dental implants increase MBF in edentulous patients. While males show higher bite force, patient age and attachment type seem not to play an important role.
Asunto(s)
Fuerza de la Mordida , Implantes Dentales , Retención de Dentadura , Dentadura Completa Inferior , Prótesis de Recubrimiento , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Prótesis Dental de Soporte Implantado , Diseño de Dentadura , Retención de Dentadura/instrumentación , Femenino , Humanos , Arcada Edéntula/rehabilitación , Masculino , Mandíbula , Persona de Mediana Edad , Estudios Retrospectivos , Factores Sexuales , Método Simple CiegoRESUMEN
OBJECTIVE: The efficacy of a topical gel with triester glycerol oxide for treating ulcerations related to new complete dentures was studied and compared with a placebo gel. MATERIALS AND METHODS: Fifty edentulous patients were enrolled in this double-blind clinical study. All subjects received new maxillary and mandibular complete dentures and were recalled 1, 3 and 7 days after denture placement. Twenty-five subjects received topical gel with triester glycerol oxide (TGO), and 25 subjects received topical gel without TGO. At each visit, pain and discomfort with the new dentures was assessed, and at the last visit, healing of ulcerations was also graded by a clinician. Subjects also graded the gel's taste, smell and ease of use. RESULTS: Specifically, there was no statistically significant difference in ulcer healing (p > 0.05), ratings of smell, taste and ease of use (p > 0.05) or pain and discomfort scores (p > 0.05). However, within-group differences were observed in pain and discomfort scores between follow-up sessions (p = 0.01 for all comparisons). CONCLUSION: Clinically, TGO gel is not effective in the treatment of mucosal injuries occurring following placement of complete dentures.
Asunto(s)
Dentadura Completa/efectos adversos , Emolientes/uso terapéutico , Glicerol/uso terapéutico , Úlceras Bucales/tratamiento farmacológico , Estomatitis Subprotética/tratamiento farmacológico , Triglicéridos/uso terapéutico , Administración Tópica , Anciano , Anciano de 80 o más Años , Método Doble Ciego , Estudios de Seguimiento , Geles , Humanos , Persona de Mediana Edad , Mucosa Bucal/efectos de los fármacos , Mucosa Bucal/lesiones , Boca Edéntula/rehabilitación , Higiene Bucal , Úlceras Bucales/etiología , Dolor/prevención & control , Satisfacción del Paciente , Placebos , Olfato/efectos de los fármacos , Fumar , Estomatitis Subprotética/etiología , Gusto/efectos de los fármacos , Acondicionamiento de Tejidos Dentales , Resultado del TratamientoRESUMEN
The treatment of edentulism with traditional complete dentures can often induce impaired masticatory function due to limited retention and stability, especially in the lower jaw. Mandibular interforaminal implants have been widely used to stabilize the dentures, consequently improving masticatory performance in edentulous individuals. The aim of the present study was to document the influence of this improved masticatory function on patient satisfaction and quality of life of patients wearing mandibular implant-supported overdentures. Sixty-two patients treated with various types of implant-supported mandibular overdentures between 2004 and 2007 were included in this retrospective study. Maximum bite force (MBF) was measured bilaterally using a device with 2 strain gauges connected to a strain gauge measurement system. All the included patients were asked to fill out visual analog scale (VAS) forms based on general and chewing satisfaction and OHIP-14 forms. Results were analyzed by the Spearman rho test. No statistically significant correlation was found between MBF values and VAS general or VAS chewing satisfaction or Oral Health Impact Profile scores (P > .05). The results indicate that MBF is not associated with the satisfaction or quality of life of implant-supported mandibular overdenture wearers.
Asunto(s)
Fuerza de la Mordida , Prótesis Dental de Soporte Implantado , Dentadura Completa Inferior , Prótesis de Recubrimiento , Satisfacción del Paciente , Calidad de Vida , Adulto , Anciano , Anciano de 80 o más Años , Actitud Frente a la Salud , Implantes Dentales/psicología , Prótesis Dental de Soporte Implantado/psicología , Retención de Dentadura , Dentadura Completa Inferior/psicología , Prótesis de Recubrimiento/psicología , Femenino , Humanos , Masculino , Masticación/fisiología , Persona de Mediana Edad , Estudios Retrospectivos , TransductoresRESUMEN
This pilot study assesses the accuracy of 2 bone-supported stereolithographic surgical templates with respect to placement of implants in originally planned positions, and it tests the precision of dental volumetric tomography planning. Two mandibles retrieved from formalin-fixed human cadavers were scanned by dental volumetric tomography for planning of the implant positions, leading to stereolithographic models and fabrication of surgical guides. The situation immediately following drilling and implant insertion by an experienced surgeon was scanned and the outcome compared with the initial planning. The 3-dimensional discrepancies were then analyzed and determined. The results show deviations of the placed implants from the original planning, especially in the vertical direction, making the seating of a prefabricated denture impossible. At present, the flapless surgery technique based on stereolithographic surgical templates appears unsafe; further improvement is required.
Asunto(s)
Implantación Dental Endoósea/instrumentación , Imagenología Tridimensional/métodos , Mandíbula/cirugía , Modelos Dentales , Cirugía Asistida por Computador/métodos , Humanos , Arcada Edéntula/rehabilitación , Mandíbula/diagnóstico por imagen , Modelos Anatómicos , Planificación de Atención al Paciente , Proyectos Piloto , Radiografía , Radioterapia de Intensidad Modulada , Reproducibilidad de los ResultadosRESUMEN
PURPOSE: To compare the retention forces of implant overdenture patrices (ball, bar, and TiSi.snap) to conventional (O-ring, metal housing, and clip) and polyvinyl siloxane (PVS)-based silicone (retention.sil 200, 400, and 600; Mucopren Soft; and GC Reline Soft) matrix materials. MATERIALS AND METHODS: Two implant analogs, in which the patrices were to be placed, were embedded parallel to each other in polyethylene blocks, and the matrices were placed in heatpolymerized acrylic blocks that were fabricated as overdentures. Ten samples were prepared for each attachment type, and 180 samples were obtained from 18 groups. All samples were placed in a chewing simulator for occlusal force application and for insertion and removal of the pieces. Retention measurements were performed with a universal testing device at the initial (10 cycles), simulated first-year (1,825 cycles), and simulated second-year (3,650 cycles) periods, assuming that the patients would insert and remove their overdenture five times daily. RESULTS: Loss of retention occurred in all the attachment systems at the end of 3,650 cycles (P < .05). The PVS matrix materials showed less retention than the O-ring and metal matrices when a ball patrix was used, while they had higher retention than bar clips when the Hader bar patrix was used (P < .05). Among the PVS matrix materials, retention.sil 200 produced the lowest retention values, whereas retention.sil 600 generated the highest. CONCLUSION: PVS matrix materials show higher retention than that achieved by yellow plastic bar matrices. However, these materials exhibit lower retention than with plastic and metal matrices of ball abutments.