Outcomes of resin-bonded attachments for removable dental prostheses.

PURPOSE: This clinical study aimed to evaluate the outcomes of resin-bonded attachments (RBAs) for precision-retained removable dental prostheses (RDPs) after at least two years of clinical maintenance. METHODS: Since December 1998, 205 RBAs (44 bonded to posterior teeth, 161 to anterior teeth) have been inserted in 123 patients (62 females and 61 males; mean age, 63.6 ± 9.6 years) who were recalled annually. The abutment teeth underwent a minimally invasive preparation limited to the enamel. RBAs were cast in a cobalt-chromium alloy with a minimum thickness of 0.5 mm and adhesively luted with a luting composite resin (Panavia 21 Ex or Panavia V5, Kuraray, Japan). We evaluated caries activity, plaque index, periodontal condition, and tooth vitality. The Kaplan-Meier survival curves were used to account for the reasons for failure. RESULTS: The mean observation time of RBAs until the last recall visit was 84.5 ± 51.3 months (range, 3.6-270.6). During the observation period, 33 RBAs debonded in 27 patients (16.1%). The 10-year success rate according to the Kaplan-Meier analysis was 58.4%, which dropped to 46.2% after 15 years of observation if debonding was considered a failure. If rebonded RBAs were regarded as surviving, the 10- and 15-year survival rates would be 68.3% and 61%, respectively. CONCLUSIONS: The use of RBAs for precision-retained RDPs appears to be a promising alternative to conventionally retained RDPs. As reported in the literature, the survival rate and frequency of complications were comparable with those of conventional crown-retained attachments for RDPs.

Replacement of Two Missing Adjacent Teeth with Two Single-Retainer Resin-Bonded Fixed Dental Prostheses with Improved Proximal Design.

PURPOSE: To present a minimally invasive treatment approach for the replacement of two missing adjacent teeth with two single-retainer resin-bonded fixed dental prostheses (RBFDPs). MATERIALS AND METHODS: Two missing adjacent premolars were restored by two RBFDPs with an innovative design of the proximal section. Both RBFDPs were digitally designed and milled from monolithic 3Y-TZP zirconia ceramic using CAD/CAM. Following construction of the anterior RBFDP, a shallow interlock was designed in the area of proximal contact in the same insertion direction as the posterior RBFDP. In this way, different paths of insertion of the RBFDPs could be provided without compromising the proximal hygiene capability. RESULTS: The presented minimally invasive restorations were successful over 5 years of clinical bservation without any complications. CONCLUSION: The presented restoration design secures the transversal position of the RBFDPs while maintaining physiologic tooth mobility. In addition, it allows for varying paths of insertion while improving hygienic conditions. Last, in case of a unilateral debonding of one retainer wing, rebonding might be possible. Int J Prosthodont 2023;36:155-160. doi: 10.11607/ijp.7711.

Fifteen-year outcome of three-unit fixed dental prostheses made from monolithic lithium disilicate ceramic.

OBJECTIVES: The purpose of this prospective study was to evaluate the clinical long-term outcome over 15 or more years of crown-retained fixed dental prostheses (FDPs) made from a lithium disilicate ceramic (IPS e.max Press, Ivoclar Vivadent AG). METHODS: Thirty-six three-unit FDPs replacing anterior (16%) and posterior (84%) teeth were inserted in 28 patients. Abutment teeth were prepared following a standardized protocol. The size of the proximal connector of the FDPs was 12 mm² (anterior) or 16 mm² (posterior). FDPs were cemented either conventionally with glass-ionomer cement (n = 19) or adhesively with composite resin (n = 17). The following parameters were evaluated at baseline, 6 months after cementation and then annually (at abutment and contralateral teeth): probing pocket depth, plaque index, bleeding on probing, and tooth vitality. RESULTS: Three FDPs were defined as drop-outs. The mean observation period of the remaining 33 FDPs was 167 months (range: 79-225 months). The survival rate (survival being defined as FDPs remaining in place either with or without complications) according to Kaplan-Meier was 48.6% after 15 years. The success rate (success being defined as free of complications and remaining unchanged) was 30.9% after 15 years. CONCLUSIONS: Fatigue and crack propagation caused by clinical aging in monolithic lithium disilicate ceramics seem to take considerable time, as shown by the presented survival and success rates after 15 years. Further long-term studies are necessary to evaluate the reliability of FDPs made from other all-ceramic materials over a period of 15 or more years.

Influence of bonding surface and bonding methods on the fracture resistance and survival rate of full-coverage occlusal veneers made from lithium disilicate ceramic after cyclic loading.

OBJECTIVES: The purpose of this laboratory study was to evaluate the influence of bonding method and type of dental bonding surface on fracture resistance and survival rate of resin bonded occlusal veneers made from lithium disilicate ceramic after cyclic loading. METHODS: Fourty-eight extracted molars were divided into three groups (N=16) depending on the preparation: within enamel, within dentin/enamel or within enamel/composite resin filling. Lithium disilicate occlussal veneers were fabricated with a fissure-cusp thickness of 0.3-0.6mm. Restorations were etched (5% HF), silanated and adhesively luted using a dual-curing luting composite resin. Test groups were divided into two subgroups, one using a only a self-etching primer, the other additionally etching the enamel with phosphoric acid. After water storage (37°C; 21d) and thermocycling (7500 cycles; 5-55°C), specimens were subjected to dynamic loading in a chewing simulator (600,000 cycles; 10kg/2Hz). Surviving specimens were loaded until fracture using a universal testing machine. RESULTS: All specimens survived artificial aging, several specimens showed some damage. ANOVA revealed that enamel etching provided statistically significantly (p≤0.05) higher fracture resistance than self-etching when bonding to enamel and dentin. Self-etching provided statistically significant (p≤0.05) higher fracture resistance for the enamel-composite group than for the enamel group. Enamel etching provided statistically significant (p≤0.05) higher fracture resistance for the enamel and dentin group than for groups enamel and enamel-composite. SIGNIFICANCE: Etching enamel improved the fracture resistance of occlusal veneers when bonding to dentin and enamel and increased the survival rate when bonding to enamel.

Fifteen-year outcome of posterior all-ceramic inlay-retained fixed dental prostheses.

OBJECTIVES: To evaluate the long-term clinical outcome of inlay-retained fixed dental prostheses (IRFDPs) made from lithium-disilicate glass-ceramic. MATERIAL AND METHODS: Forty-five IRFDPs were placed in 42 patients (21 women, mean age 36.1 years and 21 men, mean age 42.0 years). The IRFDPs replaced 4 premolars and 19 first molars in the maxilla and 4 premolars and 18 first molars in the mandible. All teeth were prepared following a standardized protocol for ceramic inlay restorations. Five of the 45 FDPs were hybrid-retained restorations, i.e. one abutment tooth with an inlay retainer and one with a full crown retainer. All restorations were fabricated from heat-pressed lithium-disilicate ceramic (IPS e.max Press, Ivoclar Vivadent AG). The minimal size of the proximal connector was 16 mm2 (4 mm × 4 mm in height and width) with a minimum occlusal ceramic thickness of 1.5 mm. Hydrofluoric acid etching (5%) and silane application was used for conditioning the bonding surfaces. Standard adhesive luting techniques were performed using a dentin adhesive and a resin composite. Standardized follow-up reports were performed annually. The survival rates were performed using the Kaplan-Meier analysis. RESULTS: The mean observation period was 100 months (minimum 4, maximum 234 months). Thirty-three FDPs (73%) failed during the observation period and had to be replaced by other restorations. The Kaplan-Meier survival rate for IRFDPs was 57% after 5 years, 38% after 8 years and 22% after 15 years, while for hybrid-retained FDPs it was 100% after 5 years, 60% after 8 years and also 60% after 15 years. CONCLUSION: With the design used in the current, study lithium-disilicate ceramic IRFDP had a high clinical failure rate and cannot be recommended for regular clinical use.

3D-tracking the regenerative potential of the mandible with micro-CTs.

PURPOSE: The treatment of large bone defects is a challenging problem especially when the mandible is affected. Bone healing is dependent on the defect size and the integrity of periosteum. So far, these both aspects have not been investigated separately. The aim of this study was to evaluate the healing potential of the mandibular bone with the help of three-dimensional micro-computed tomography (CT). METHODS: The angle of the mandible was exposed in 15 Wistar rats. A 3-mm core of bone was removed with a trephine. The local periosteum next to the defect was excised. Animals were randomized in five groups, which were ended 5, 10, 15, 28 and 56 days after operation. The mandible was excised and underwent micro-CT. For statistical evaluation, t-test statistics and regression analysis were applied. RESULTS: Characteristics of the defects began to change on the tenth postoperative day. Fifteen days until 4 weeks after intervention new mineralization processes could be observed. New bone grew from the borders into the defect. In the 2D study, bone apposition changed significantly from the beginning to week 8 (0.08 to 0.74 mm) as well as the 3D bone gain (0.05 % to 29.67 %) in t-test statistical evaluation. For development of the bone volume inside the defect linear as well as exponential regression analysis revealed a statistically significant connection. CONCLUSIONS: This study quantified the amount of newly grown bone during osseous regeneration. We could show that the mandible itself provides regenerative capacity without any intact periosteum.