[Effects of Implant Position on Clinical Crown Length and Papilla Fills in Implant-supported Maxillary Central Incisors].

OBJECTIVE: To determine the effect of implant position on clinical crown length and papilla fills in implant-supported maxillary central incisors. METHODS: One implant replacing the 11th or 21st tooth was given to 158 patients who lost a maxillary central incisor after trauma. The contra-lateral central incisors were used as controls. The three-dimensional positional parameters were estimated using standardized photographs of the cast models, clinical photographs and peri-apical radiographs. Paired t tests were performed to examine the differences between the implants and the control teeth in clinical crown length, papilla fills, proximal bone crest levels, and the horizontal implant-teeth distance at the mesial and distal implant. Pearson correlations were used to identify the implant positional parameters associated with crown length and papilla fills. RESULTS: The implant-supported crowns were statistically longer than the controls [(10.9±1.1) mm vs. (10.4±0.8) mm, P<0.05]. Greater papilla fills were found in the mesial implants and distal contra-lateral teeth compared with the distal implants (P<0.000 1). The implants had higher levels of mesial proximal bone crest than the distal [(2.2±1.4) mm vs. (1.2±1.5) mm, P<0.05]. The oro-facial position of the implants was associated with the crown length (R=0.602, P=0.001). But the crown length was not correlated with the sagital angulation of the implants or the vertical distance from the implant fixture to the soft tissue margin. The proximal bone crest level was correlated with the papilla fill height (R=0.400, P=0.001). CONCLUSION: An implant positioned buccally results in longer crown length. Minor buccal angulations of the implant do not necessarily result in increased crown length. Appropriate position and input depth may help avoid bone absorption and papilla shrinkage.

Crown color match of implant-supported zirconia and porcelain-fused-to-metal restorations: a spectrophotometric comparison / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aimed to compare the crown color match of implant-supported zirconia restorations and porcelain-fused-to-metal (PFM) restorations in the anterior maxillary region through spectrophotometric evaluation.</p><p><b>METHODS</b>Eighteen patients with 29 implant-supported single crowns in the anterior maxillary area were recruited. Eleven of the implant crowns were zirconia restorations and 18 were PFM restorations. Color matching of the implant crown with contra-lateral/ neighboring tooth at the position of body 1/3 of the crown was assessed using a spectrophotometer (SpectroShade) in CIE L* a* b* coordinates. Subjective crown color match scores were evaluated. Independent sample t test of SPSS 17.0 was used to compare the difference between zirconia restoration and PFM restoration. Spearman correlation was used to analyze the relationship between the spectrophotometric color difference and the subjective crown color match score. Descriptive statistics was used to analyze the distribution of color coordinates of natural anterial teeth.</p><p><b>RESULTS</b>The crown color of the implant-supported zirconia restorations and PFM restorations were both lighter than that of natural teeth (delta L, 4.5 +/- 3.2, 1.0 +/- 2.6). The lightness difference induced by zirconia restorations was significantly larger than that induced by PFM restorations (P=0.004). The spectrophotometric crown color difference (delta E) induced by zirconia restorations (7.0 +/- 2.8) was significantly larger than that induced by PFM restorations (4.0 +/- 1.9) (P=0.002), and both values were beyond the clinical thresholds (3.7).</p><p><b>CONCLUSION</b>The spectrophotometric crown color difference induced by zirconia restorations was significantly larger than that induced by PFM restorations. However, they were indistinguishable in subjective evaluation.</p>

[Influence of all-ceramic and porcelain-fused-to-metal restorations on peri-implant gingival discoloration:a spectrophotometric comparison].

PURPOSE: To compare the gingival discoloration of implant supported all-ceramic and porcelain-fused-to-metal (PFM) restorations in anterior maxillary region by spectrophotometric evaluation. METHODS: Eighteen patients with 29 implant-supported single crowns (11 all-ceramic restorations, 9 PFM restorations with titanium abutment and 9 PFM restorations with golden alloy abutment) in anterior maxillary area were recruited. The color difference between peri-implant gingiva and contra-lateral/neighboring mucosa was assessed using a spectrophotometer in CIELab coordinates. Subjective gingival discoloration scores were evaluated by clinician. SPSS17.0 software package was used to analyze the data. RESULTS: There was no significant difference between all-ceramic group (3.4±1.8) and PFM group (4.9±3.4) spectrophotometrically. No significant difference was found between all-ceramic restorations and PFM restorations with titanium abutment (3.5±2.5), and no significant difference was found between PFM restorations with titanium abutment and PFM restorations with gold alloy abutment (6.3±3.8) either. There was, however, significant difference between all-ceramic restorations and PFM restorations with gold alloy abutment (P=0.037). There was no significant difference between all-ceramic group and PFM group regarding the clinical gingival discoloration score (GDS), and this gingival discoloration score was found to have significant correlation with the spectrophotometric evaluation (rs=0.426, P=0.021). CONCLUSIONS: There is no significant difference between all-ceramic group and PFM group as regard to both spectrophotometric and clinical evaluation of gingival discoloration, but the PFM restorations with gold alloy abutment induce significantly higher discoloration than all-ceramic restorations.