Development of a non-titration potentiometric method for the determination of acidity in vinegar

The acidity of a solution is associated with the concentration of Brønsted acids. This work proposes a new non-titrimetric potentiometric method using citrate buffer for the determination of vinegar acidity. The difference between the pH values before and after the addition of a diluted vinegar sample to 10 mmol L^-1 citrate buffer (pH 5.5) was related to the acetic acid concentration. The dynamic range of the quadratic analytical curve was from 3.5 to 20 mmol L^-1 (R² = 0.998). The repeatability was 0.8% for acetic acid at 0.01 mol L^-1. Comparison with the conventional titration method showed an error between 0.7% and 4.64% (n = 9) for analysis of commercial vinegar samples The behaviour of the system could be explained using the buffering function.

Worldwide trends on molar incisor and deciduous molar hypomineralisation research: a bibliometric analysis over a 19-year period

AIM

To identify the worldwide trends in scientific evidence and gaps in knowledge regarding molar incisor hypomineralisation (MIH) and deciduous molar hypomineralisation/hypomineralised second primary molars (DMH/HSPM), exploring the contribution of authors and countries, possible etiological factors and proposed treatments, in order to guide future research in the area.

METHODS

Searches were conducted in MEDLINE, Scopus, Web of Science, Cochrane Library, Lilacs/BBO, Embase and Google Scholar. Studies employing the terms MIH, DMH/HSPM and their linguistic variations were included. The following data were extracted: title, authors, year and journal of publication and first author's affiliation country. Studies were categorized according to topic, dentition, study design, etiological factors and types of treatments. Categories were analysed in relation to their distribution, co-occurrence, cross-correlation and/or autocorrelation.

RESULTS

Five hundred and three studies were included. The most published authors were Manton D (n = 47), de Souza JF (n = 22) and Ghanim A (n = 22) and four main collaboration clusters have been identified. Most of the studies were conducted on permanent dentition (MIH) (87.4%); with observational design (57.2%). The "European Archives of Paediatric Dentistry" was the most published journal (13.3%) and a significant increase in the number of publications was observed in the last decade. MIH was most studied in relation to prevalence/incidence, systemic factors involved in its aetiology and treatment with composite restorations, while a gap in knowledge was observed for extraction and sealants. Less studies were published on DMH/HSPM and most of them evaluated risk factors or prevalence/incidence. The gap of knowledge was observed in relation to treatments and patient's quality of life.

CONCLUSIONS

This bibliometric review provided a comprehensive overview of research in MIH and DMH/HSPM over the past 19 years. Within the limitations of the present study, the following conclusions can be drawn: global trends point to an increasing peak of scientific publication, especially in the last decade, while there is a shortage of clinical studies on treatments, mainly evaluating tooth extractions. Finally the multifactorial nature should be further explored, considering environmental and systemic factors together.

Síntese e Caracterização de Compósitos Restauradores Remineralizantes com Partículas de Ionômero de Vidro-Ca Pré-Reagidas (PRG-Ca)

O objetivo desta pesquisa foi sintetizar e caracterizar compósitos restauradores experimentais (CRE) com partículas de ionômero de vidro-cálcio pré-reagidas (PRG-Ca). As PRG-Ca foram obtidas a partir da síntese de um vidro de cálcio fluoraluminosilicato e sua reação com ácido poliacrílico. As PRG-Ca foram silanizadas e CRE foram produzidos: E0, E1, E2, E3, E4, E5 e E6. A matriz orgânica (40% p/p) foi composta de Bis-GMA / TEGDMA e canforoquinona / etil N,N-dimetil-4aminobenzoato. O compósito base (E0) continha 60% p/p de partículas de bário-boro-silicato (BaBSi), sendo o controle. Em E1, E2, E3, E4, E5 e E6, o BaBSi foi parcialmente substituído por 10, 20, 30, 40, 50 e 60% p/p de PRG-Ca, respectivamente. O Empress Direct (ED) foi a referência comercial utilizada. Foram avaliadas as seguintes propriedades: grau de conversão (GC), rugosidade (Ra), dureza Knoop (DK), resistência à flexão (RF), módulo de flexão (MF), absorção (Ab), solubilidade (Sl), brilho (GU), translucidez (PT), cor (OE) e o potencial remineralizante (PR) através de microtomografia. Os dados foram submetidos à análise de variância e teste de Tukey HSD (a 0,05). Quanto à Ra, DK e GU, não houve diferença entre os CRE. O aumento de PRG-Ca diminuiu GC, RF, MF e PT e aumentou Ab, Sl, OE e PR. Na maioria das propriedades avaliadas, ED apresentou comportamento intermediário aos CRE. E0 e ED não apresentaram PR. Os CRE com PRG-Ca demonstraram ser materiais bioativos promissores, apresentando bom desempenho nas propriedades avaliadas e um potencial remineralizante que aumenta com uma maior concentração de PRG-Ca.Palavras-chave: Resinas Compostas. Remineralização Dentária. Propriedades Físicas e Químicas.

Análise Topográfica e por Micro-CT das Margens em Esmalte de Restaurações com Compósitos Experimentais Submetidas ao Biofilme Cariogênico

Avaliou-se as margens em esmalte de restaurações realizadas com compósitos experimentais à base de quaternário de amônio, como: (2-(dimethylamino) ethylmetacrylate 1-bromododecane) (DMADDM) e o (2-(dimethylamino) ethylmetacrylate 1-bromohexadecane) (DMAHDM) em diferentes concentrações (5% e 10%) através de perfilometria 3D sem contato e escaneamento por micro-CT. Confeccionou-se 35 blocos de esmalte bovino de 4x4mm que receberam cavidades padronizadas e divididos em 7 grupos (n5) de acordo com o material restaurador utilizado: 1) DMADDM 5%, 2) DMADDM 10%, 3) DMAHDM 5%, 4) DMAHDM 10% 5) Controle (sem monômero antimicrobiano), 6) resina composta comercial e 7) ionômero de vidro comercial. Os blocos foram submetidos a um biofilme de S. mutans. Após, os blocos foram limpos e analisados através do Perfilômetro e micro-CT. Os dados foram submetidos à análise de variância e ao teste de Kruskal-Wallis. A perfilometria mostrou que todos os grupos obtiveram diferenças na rugosidade superficial e degrau formado entre a área exposta e não-exposta ao biofilme, sendo o grupo 5 o que apresentou o maior deles. A análise do micro-CT mostrou que todos os grupos, com exceção do grupo 7, exibiram perda mineral, sendo esta menor nos que apresentavam algum monômero antimicrobiano (p<0,05). Conclui-se que a presença do quaternário de amônio nos compósitos experimentais foi capaz de minimizar as alterações em esmalte nas margens das restaurações. No entanto, o CIV foi o que apresentou o maior poder de proteção contra os danos provocados pelo desafio cariogênico.Palavras-chave: Compósitos. Quaternário de Amônio. Esmalte.

Dental caries in the fossil record: a window to the evolution of dietary plasticity in an extinct bear

During the late Pleistocene of North America (≈36,000 to 10,000 years ago), saber-toothed cats, American lions, dire wolves, and coyotes competed for prey resources at Rancho La Brea (RLB). Despite the fact that the giant short-faced bear (Arctodus simus) was the largest land carnivoran present in the fauna, there is no evidence that it competed with these other carnivores for prey at the site. Here, for the first time, we report carious lesions preserved in specimens of A. simus, recovered from RLB. Our results suggest that the population of A. simus from RLB was more omnivorous than the highly carnivorous populations from the Northwest. This dietary variation may be a consequence of different competitive pressures.

Dissolution, dislocation and dimensional changes of endodontic sealers after a solubility challenge: a micro-CT approach

AIM

To evaluate, using a novel micro-CT approach, the solubility and dimensional changes of an MTA-based sealer inside the root canal system after a solubility challenge. The MTA-based material (MTA Fillapex) was compared to a gold standard epoxy-based endodontic sealer (AH Plus).

METHODOLOGY

Ten human mandibular premolars with a single canal were divided randomly into two groups (n = 5) according to the sealer used. The canals were instrumented using the Reciproc System (VDW) with a R40 file and filled with R40 gutta-percha cones and one of the sealers. The filled canals were immediately scanned in a micro-CT, and after that, the teeth were immersed in 20 mL phosphate-buffered saline (PBS) at 37 °C for 7 days, when they were removed and rescanned. Final image stacks were registered against the initial stacks and the numerical difference between the initial and final volume of the filling material was obtained. Calculations were performed to identify dimensional changes of the filling material. All image stacks were 3D rendered to disclose areas of dislocation of the filling material inside or outside the root canal. The Shapiro-Wilk's test revealed that data were normally distributed; thus, the Student's t-test was used to detect statistically significant changes, assuming a 5% α-error.

RESULTS

No significant changes were seen for the percentage volume of material lost after the solubility challenge for both AH Plus and MTA Fillapex groups (1.44% and 1.16%, respectively). A significant difference was, however, found for the volume of filling material which revealed dimensional changes after the solubility test (6.68% for MTA Fillapex and 1.09% for AH Plus). In fact, observation of 3D models disclosed that MTA Fillapex was associated with material extrusion through the foramen in all but one sample. In AH Plus filled samples, no material extrusion was detected.

CONCLUSIONS

Although the solubility of both sealers was similar using this novel micro-CT approach, MTA Fillapex was associated with significant dimensional changes related to material extrusion through the apex after PBS storage compared to AH Plus.

Caries-removal effectiveness of a papain-based chemo-mechanical agent: A quantitative micro-CT study

The aim of this study was to access the effectiveness and specificity of a papain-based chemo-mechanical caries-removal agent in providing minimum residual caries after cavity preparation. In order to do it, extracted carious molars were selected and scanned in a micro-CT before and after caries-removal procedures with the papain-based gel. Similar parameters for acquisition and reconstruction of the image stacks were used between the scans. After classification of the dentin substrate based on mineral density intervals and establishment of a carious tissue threshold, volumetric parameters related to effectiveness (mineral density of removed dentin volume and residual dentin tissue) and specificity (relation between carious dentin in removed volume and initial caries) of this caries-removal agent were obtained. In general, removed dentin volume was similar or higher than the initial carious volume, indicating that the method was able to effectively remove dentin tissue. Samples with an almost perfect accuracy in carious dentin removal also showed an increased removal of caries-affected tissue. On the contrary, less or no affected dentin was removed in samples where some carious tissue was left in residual dentin. Mineral density values in residual dentin were always higher or similar to the threshold for mineral density values in carious dentin. In conclusion, the papain-based gel was effective in removing carious dentin up to a conservative in vitro threshold. Lesion characteristics, such as activity and morphology of enamel lesion, may also influence caries-removal properties of the method.

Influence of electronic apex locators and a gutta-percha heating device on implanted cardiac devices: an in vivo study

AIM

To evaluate the potential for electromagnetic interference (EMI) of electronic apex locators (EALs) and a gutta-percha heating device (HD) in patients with implantable cardiac pacemakers (ICPs) or cardioverter-defibrillators (ICDs).

METHODOLOGY

Two types of EALs (Romiapex A-15 and Novapex) and a HD (Touch'n Heat) were tested in patients followed in an outpatient clinic for cardiac arrhythmias. The heart rhythm was monitored on a computer screen during all experimental phases. After baseline data collection, the patient held each appliance (turned on) for 30 s, simulating their clinical use. If background noise was detected on the cardiac monitor, the sensitivity of the ICP/ICD was lowered by the cardiologist to evaluate the intensity of the detected EMI.

RESULTS

Twelve patients were evaluated (5 female and 7 male), and in nine instances, background noise in their cardiac devices related to the use of the endodontic devices was detected (6 patients). After lowering the sensitivity of the cardiac implants, three patients had more severe EMI in six instances, including pauses in ICP function. The presence of a symptomatic or asymptomatic pause was related to the patient's underlying heart rhythm. The HD device produced background noise more often compared to EALs. These were associated with more severe types of EMI.

CONCLUSION

The EALs and gutta-percha HD were capable of causing background noise detection or pauses in cardiac implants in vivo. The use of electronic dental devices nearby patients with cardiac implants should be carefully considered in clinical practice.

Exploiting the potential of free software to evaluate root canal biomechanical preparation outcomes through micro-CT images

AIM

To propose an automated image processing routine based on free software to quantify root canal preparation outcomes in pairs of sound and instrumented roots after micro-CT scanning procedures.

METHODOLOGY

Seven mesial roots of human mandibular molars with different canal configuration systems were studied: (i) Vertucci's type 1, (ii) Vertucci's type 2, (iii) two individual canals, (iv) Vertucci's type 6, canals (v) with and (vi) without debris, and (vii) canal with visible pulp calcification. All teeth were instrumented with the BioRaCe system and scanned in a Skyscan 1173 micro-CT before and after canal preparation. After reconstruction, the instrumented stack of images (IS) was registered against the preoperative sound stack of images (SS). Image processing included contrast equalization and noise filtering. Sound canal volumes were obtained by a minimum threshold. For the IS, a fixed conservative threshold was chosen as the best compromise between instrumented canal and dentine whilst avoiding debris, resulting in instrumented canal plus empty spaces. Arithmetic and logical operations between sound and instrumented stacks were used to identify debris. Noninstrumented dentine was calculated using a minimum threshold in the IS and subtracting from the SS and total debris. Removed dentine volume was obtained by subtracting SS from IS.

RESULTS

Quantitative data on total debris present in the root canal space after instrumentation, noninstrumented areas and removed dentine volume were obtained for each test case, as well as three-dimensional volume renderings.

CONCLUSION

After standardization of acquisition, reconstruction and image processing micro-CT images, a quantitative approach for calculation of root canal biomechanical outcomes was achieved using free software.

Assessment of coronal leakage of a new temporary light-curing filling material in endodontically treated teeth

INTRODUCTION

The aim of this study was to evaluate the sealing ability of a new temporary filling material X-Temp LC (DFL, São Paulo, SP, Brazil) compared with that obtained for Coltosol (Vigodent, Rio de Janeiro, RJ, Brazil) and Vitro Fill (DFL, Rio de Janeiro, RJ, Brazil), using a dye penetration test.

METHODS

Standard endodontic access cavities were prepared in 75 human premolars. The teeth were divided into five groups (n = 15 for each group), including a positive (no sealing of access cavity) and a negative control (Filtek Z350 XT, 3M, São Paulo, SP, Brazil). In the experimental groups, the access cavities were sealed with one of the three tested materials. After that, the teeth were immersed in 10% Indian ink for 14 days. The teeth were then rinsed, dried, sectioned in bucco-lingual direction and evaluated under a stereomicroscope using scores for dye penetration. Data were analyzed using Kruskall-Wallis and Student-Newman-Keuls tests (α =0.05).

RESULTS

Positive control sections exhibited complete dye penetration and negative control had no specimen showing marginal leakage. X-Temp LC and Coltosol showed similar results, with no statistical difference between them. Vitro Fill exhibited the highest dye penetration among the experimental groups.

CONCLUSION

The results of this in vitro study suggest that all temporary restorative materials exhibit some degree of marginal leakage. X-Temp LC and Coltosol, however seal better than Vitro Fill glass ionomer cement.

3D-microleakage assessment of adhesive interfaces: exploratory findings by μCT

OBJECTIVES

To explore the feasibility of a 3D-microleakage protocol for the evaluation of various configurations of adhesive-tooth interfaces.

METHODS

Three different kinds of specimens were prepared: (1) a Class-I composite restoration placed without any bonding to maximize gap formation at the interface; (2) a glass-fiber post cemented with a self-adhesive composite cement into a prepared root canal; and (3) inlay MOD composite restorations placed with either a 1-step self-adhesive or a 2-step etch-and-rinse composite cement. After silver-nitrate (AgNO3) infiltration, the specimens were scanned using a Skyscan 1172 X-ray microtomograph (μCT; Skyscan Bruker) at 100kV, 100μA and 7.8-9.5μm resolution. Projection images were reconstructed, after which maximum-intensity projections (MIPs) and 3D-volumetric renderings were produced. For the inlays, an additional conventional stereomicroscopic (SM) microleakage evaluation was accomplished after specimen sectioning.

RESULTS

MIPs and 3D-renderings from specimens (1) and (2) revealed strongly varying microleakage patterns along the marginal gap/interface. For the specimens of setup (3), the high radiopacity of the 2-step composite cement hindered evaluation of the MIPs. MIP-microleakage patterns along the enamel margin of the restoration cemented with the 1-step composite cement corresponded well to the stereomicroscopic images.

SIGNIFICANCE

The reported μCT-protocol revealed good sensitivity to detect AgNO3 infiltration at the adhesive-tooth interface when considerable microleakage was present. When microleakage was less apparent and spread in a more diffuse pattern, evaluation with μCT was less sensitive compared to stereomicroscopic evaluation.

Does DIAGNOdent provide a reliable caries-removal endpoint?

OBJECTIVES

To compare mineral density of residual dentine after excavation with different caries-removal techniques and to evaluate the diagnostic potential of laser-induced fluorescence (LIF), measured by DIAGNOdent, as a tool to determine the caries-removal endpoint.

METHODS

Carious teeth were excavated by tungsten-carbide round burs (Komet), ceramic burs (CeraBurs, Komet), sono-abrasion (Cariex TC tips, Kavo), and by chemo-mechanical excavation using two enzyme-based solutions (exp. SFC-V and SFC-VIII, 3M-ESPE) or a sodium hypochlorite-based solution (Carisolv, MediTeam). The caries-excavated teeth were scanned by micro-CT (1172, Skyscan), after which the mineral density at the bottom dentine was correlated to LIF measurements at the same region. A micro-CT threshold for dentine caries was defined by comparison with surface-hardness measurements. The intensity of dentine staining was evaluated by analysing the component 'L*' in CIE-L*a*b-converted images from the excavated teeth.

RESULTS

No statistically significant difference in mineral density was found at the bottom of the cavities prepared with the different caries-excavation techniques, except for exp. SFC-V that left residual dentine with a significantly higher mineral density than when CeraBurs were used (Tukey-Kramer, p<0.05). Absence of residual caries was associated with darker staining of dentine. No significant correlation was found between the distance from the deepest cavity point to the pulp-chamber roof and LIF measurements. A strong negative correlation (R=-0.86, p<0.01) was however found between L* values and LIF measurements, indicating that staining in residual dentine leads to higher LIF measurements.

CONCLUSIONS

LIF measured by DIAGNOdent is influenced by staining in residual dentine. Therefore, its use to determine the caries-removal endpoint is doubtful.

Bonding effectiveness and interfacial characterization of a nano-filled resin-modified glass-ionomer

Glass-ionomers (GIs) exhibit excellent clinical bonding effectiveness, but still have shortcomings such as polishability and general aesthetics. The aims of this study were (1) to determine the micro-tensile bond strength (microTBS) to enamel and dentin of a nano-filled resin-modified GI (nano-RMGI; Ketac N100, 3M-ESPE), and (2) to characterize its interfacial interaction with enamel and dentin using transmission electron microscopy (TEM).

METHODS

The nano-RMGI was used both with and without its primer, while a conventional RMGI restorative material (conv-RMGI; Fuji II LC, GC) and a packable conventional GI cement (conv-GI; Fuji IX GP, GC) were used as controls. After bonding to freshly extracted human third molars, microspecimens of the interfaces were machined into a cylindrical hourglass shape and tested to failure in tension. Non-demineralized TEM sections were prepared and examined from additional teeth.

RESULTS

The microTBS to both enamel and dentin of nano-RMGI and conv-GI were not statistically different; the microTBS of non-primed nano-RMGI was significantly lower, while that of conv-RMGI was significantly higher than that of all other groups. TEM of nano-RMGI disclosed a tight interface at enamel and dentin without surface demineralization and hybrid-layer formation. A thin filler-free zone (<1 microm) was formed at dentin. A high filler loading and effective filler distribution were also evident, with localized areas exhibiting nano-filler clustering.

CONCLUSIONS

The nano-RMGI bonded as effectively to enamel and dentin as conv-GI, but bonded less effectively than conv-RMGI. Its bonding mechanism should be attributed to micro-mechanical interlocking provided by the surface roughness, most likely combined with chemical interaction through its acrylic/itaconic acid copolymers.

Microscopic investigation of artificially demineralized surface enamel exposed to controlled intra-oral periods

BACKGROUND

Arrest and regression of enamel caries is generally followed by clinical surface changes in enamel. The aim of this study was to evaluate microscopic surface changes in demineralized enamel submitted to toothbrushing with a fluoridated dentifrice or to a fluoridated gel in situ.

METHODS

Enamel blocks demineralized by an acidic gel, were built in plates of five volunteers during three periods of 14 days each: exposure to the oral cavity (C+); brushing with a fluoridated dentifrice three times a days (B); application of a 2 per cent sodium fluoride gel and exposure to the oral cavity (F). Eight blocks were kept in 100 per cent humidity under refrigeration as negative controls (C-).

RESULTS

Stereomicroscopic examination revealed that 15, 47.4 and 30 per cent of samples from C+, B and F presented enamel cavitation after the experimental period. The demineralized enamel area in these groups decreased considerably compared to C-, both in cavitated and non-cavitated samples, although it was statistically significant only in cavitated samples from B (p=0.003; t test). Scanning electron microscopy revealed that C+ and F retained irregularities caused by the acid challenge, while B presented a more leveled profile of the enamel surface.

CONCLUSIONS

Exposure of demineralized enamel to intra-oral periods reduced the demineralized enamel area. Tooth brushing enhanced this reduction, because of surface abrasion.

Biological restorations as an alternative treatment for primary posterior teeth

A case of oral rehabilitation in a 4-year-old girl, in which the posterior teeth were restored using biological restorations, is described. The tooth fragments were selected from a bank of tooth tissues and bonded with dual-cure composite cement to prepared teeth. The results were satisfactory regarding retention, aesthetic and mastication, but disadvantages included long clinical appointments, laborious technique and possible fracture or degradation between the margins of the fragment and the tooth surface.

Bilateral connation of permanent mandibular incisors: a case report

Connated teeth are the consequences of developmental anomalies leading to the eruption of joined elements. According to current definitions, gemination occurs when one tooth bud tries to divide, while fusion occurs if two buds unite. Clinical experience shows, however, that diagnosis can be complicated due to superimposed anomalies. This report describes a unique case of bilateral fusion of permanent mandibular incisors and discusses the differential diagnosis and possible future treatment options anticipated for this particular case.

Measurement of bioreactor perfusion using dynamic contrast agent-enhanced magnetic resonance imaging

Dynamic magnetic resonance imaging was used to monitor solute diffusion through aggregates of Chinese hamster ovary cells growing on macroporous carriers in a fixed-bed bioreactor. Diffusion-weighted (1)H magnetic resonance imaging (MRI) and scanning electron microscopy demonstrated that cell growth in the bioreactor was heterogeneous, with the highest cell densities being found at the periphery of the carriers. T(1)-weighted magnetic resonance imaging measurements of the inflow of a commonly used magnetic resonance contrast agent, gadolinium-diethylenetriaminopentaacetic acid (Gd-DTPA), showed that migration of the agent through the peripheral cell masses could be explained by diffusion. However, appearance of the contrast agent in the center of the carriers was too fast to be explained by simple diffusion and indicated that these regions were perfused by convective flow. The average diffusivity of Gd-DTPA through the cell mass was found to be (2.4 +/- 0.2) x 10(-10) m(2) sec(-) (mean +/- SEM). This technique will be useful in the characterization and development of high-cell-density bioreactor systems, in which solute transport plays a critical role in cell growth and physiology.

Real time monitoring biomass concentration in Streptomyces clavuligerus cultivations with industrial media using a capacitance probe

On-line monitoring biomass concentration in mycelial fed-batch cultivations of Streptomyces clavuligerus grown with soluble and partially insoluble complex media, was investigated with an in-situ capacitance probe fitted to an industrial pilot-plant tank. Standard off-line and on-line biomass determinations, including cell dry weight, packed mycelial volume, viscosity, DNA concentration and total CO(2) evolution in the exhaust gases, were performed throughout the experiments and compared to on-line capacitance measurements. Linear relations between capacitance and all other measurements were developed for both media that hold only in defined process phases, depending on the biomass state and the amount of insoluble matter present. For the industrial complex culture media good linear relations were obtained in the fast growth phase between capacitance and DNA concentration and total CO(2) evolution, while in the subsequent transition and stationary phases only with apparent viscosity was a reasonable correlation found. The capacitance probe was shown to be a valuable tool for real-time monitoring biomass concentration in industrial-like cultivation of mycelial streptomycetes.

Effects of preculture variability on clavulanic acid fermentation

The production profile of clavulanic acid by Streptomyces clavuligerus was shown to be strongly dependent on inoculum activity. Two sets of fermentations (A and B) were investigated at industrial pilot-plant scale using complex media. Type A fermentations were inoculated using late exponential growth phase mycelia. Type B fermentations were inoculated using mycelia harvested at stationary phase. Productivities throughout type A fermentations were consistently higher than type B, reaching a maximum at about 70 h and then decaying to the same final productivities at 140 h of type B runs. Several scheduling alternatives, based on combinations of the two inocula types and different fermentation lengths, were compared in terms of the overall process economics (fermentation and downstream). An increase of ca. 22% on the overall process profit is predicted using late exponential growth phase inocula and a fermentation duration of only 96 h. A new operating strategy was thus proposed for inoculum production based on the control of preculture activity using off-gas analysis. This method ensures higher productivity and better batch-to-batch reproducibility of clavulanic acid fermentations than traditional methods based on constant age inocula.